Third Five-Year Review Report

Hooker S-Area Superfund Site Niagara Falls

Niagara County, New York

Prepared by:

United States Environmental Protection Agency Region 2

New York, New York

September 2009

Five-Year Review Summary Form SITE IDENTIFICATION

Site name (from WasteLAN): Hooker S-Area Superfund Site

EPA 10 (from WasteLAN): NYD980651 087

NPL status: X Final 0 Deleted 0 Other (specify)

Remediation status (choose all that apply): Under Construction Operating X Complete

Multiple OUs? YES X NO Construction completion date: 9/18/2002

Are portions of the Site and/or investigated adjacent properties in use or suitable for reuse? Has site been put into reuse? X YES 0 NO 0 N/

REVIEW 51A1U5

Lead agency: X EPA State 0 Tribe 0 Other Federal Agency

Author name: Kevin Willis

Author title: Remedial Project Author affiliation: EPA , Manager

Review period: 09/27/2004 to 912712009

Date(s) of site inspection: March 30, 2009

Type of review: o Post-SARA 0 Pre-SARA o NPL-Removal only o Non-NPL Remedial Action Site o NPL State/Tribe-Iead X statutory 0 Regional Discretion

Review number: o 1 (first) 02 (second) X 3 (third) 0 Other (specify)

Triggering action: o Actual RA On-site Construction at au # o Actual RA Start at OU#__-o Construction Completion X previous Five-Year Review Report o Other (specify)

Triggering action date (from WasteLAN): 9/27/2004

Due date (five years after triggering action date): 09/27/2009

Does the report include recommendation(s) and follow-up action(s)? yes X no Is human exposure under control? X yes o no Is contaminated groundwater under control? X yes o no o not yet determined Is the remedy protective of the environment? X yes o no o not yet determined

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Issues, Recommendations and Follow-Up Actions

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. Table 5 of this report includes suggestions for improving, modifying; and/or adjusting these activities. 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.

Protectiveness Statement

The remedy has been implemented and it has been determined that the remedy is functioning as intended and remains fully protective of human health and the environment.

Executive Summary

This is the third Five-Year Review for the Hooker S-Area Superfund site. The site is located in the City ofNiagara Falls, Niagara County, New York. The assessment ofthis Five-Year Review is that the remedial systems at the site are operating as intended, are well maintained and continue to protect human health and the environment.

Five-Year Review Report

Table of Contents

I. Introduction : : 1

II. Site Chronology 1

III. Background : 1

IV. Remedial Actions : 3

V. Progress Since the Last Five-Year Review 14

VI. Five-Year Review Process · 15

VII. Technical Assessment 16

VIII. Recommendations and Follow-up Actions 18

IX. Protectiveness Statement. 19

X. Next Review 19

Tables: Table 1 Chronology of Site Events Table 2 List ofDocuments Reviewed Table 3 Comparison of Groundwater Cleanup Goals Table 4 Acronyms Used in this Document Table 5 . Other Comments on Operation, Maintenance, Monitoring, and Institutional

Controls I

Attachments: Site Map

I. Introduction

This is the third Five-Year Review for the Hooker S-Area Superfund 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 9355.7­03B-P (June 2001). The purpose of a Five-Year Review is to assure that implemented remedies are protective of public health and the environment and that they function as intended by the decision document(s). This report will become part ofthe site file.

This Five-Year Review is being conducted as a statutory requirement. In accordance with the Section 1.3.3 ofthe Five-Year Review Guidance, a subsequent statutory Five-Year Review is triggered by the signature date ofthe previous Five-Year Review Report. The trigger for this subsequent Five-Year Review is the date of the previous Five-Year Review Report, which was September 27,2004.

The Hooker S-Area site remedy is a comprehensive source control remedy that is being handled as a single operable unit and continues to be in well-maintained condition and is fully protective ofhuman health and the environment.

II. Site Chronology

The chronology ofsite events related to the remediation ofthe S-Area site is summarized in Table 1.

III. Background

The Hooker Chemical S-Area site is an 8-acre industrialland:fill owned by the Occidental Chemical Corporation (OCC). It is located at the southeast comer ofOCC's Buffalo Avenue Chemica1Plant in Niagara Falls, New York, along the Niagara River. Adjacent to the land:fill is the City ofNiagara 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 ofNiagara 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 land:filllies atop approximately 30 feet ofsoil, clay, till, and manmade :fill on an area reclaimed from the Niagara River. Beneath these materials is fractured bedrock.

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History ofContamination and Initial Response

Hooker Chemical & Plastics Corporation (now OCC) disposed of approximately 63,000 tons of chemical processing wastes into the landfill from 1947 to 1961. The landfill also w~ used by OCC

. for the disposal of other wastes and debris, a practice that ended in 1975. Two lagoons for non­hazardous waste from plant operations were located on top ofthe landfill and were operated under New York State permits until 1989, when OCC discontinued operating these lagoons.

Basis for Taking Action

During an inspection of the DWTP in 1969, chemicals were found in the bedrock water intake structures of the DWTP. In 1978, sampling of the structures and bedrock water intake tunnel revealed chemical contamination. It was determined that the process wastes that OCC had disposed ofin the S-Area landfill were migrating as a Dense Non-Aqueous Phase Liquid (DNAPL) through fractures in the bedrock aquifer system and entering the DWTP water intake tunnel via these fractures.

On December 20, 1979, the United States Department ofJustice, on behalfofthe 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 of New 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 ofthe Clean Water Act and the common law ofnuisance. 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 ofthe site and the adjacent DWTP. The first settlement agreement, entitled "Stipulation and Judgment Approving Settlement Agreement" (Settlement Agreement"), was signed on January 10, 1984 and approved and entered by the Court on April 15, 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 ofOntario, 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 ofAppeals for the Second Circuit on appeal. United States v. Hooker Chemical & Plastics Corp., 776 F.2d 410 (2nd Cir. 1985).

At that time, 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, ifany, additional responSe actions were necessary. The process to evaluate various remedial alternatives was called a Requisite Remedial Techrlology (RRT) Study (i.e.! the equivalent ofa CERCLA feasibility study). Based on the results ofthe additional investigations and the RRT Study, which were performed by OCC in the late 1980s, the parties negotiated a second agreement,

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entitled "Stipulation on Requisite Remedied Technology Program" (RRT Stipulation) to remediate those areas ofcontamination at the site which would not be addressed by the 1985 remedy. 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 RRT Stipulation was incorporated into, supplemented and modified the 1985 Settlement Agreement.

IV. 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 Departments of Environmental Conservation (NYSDEC) and New York State Department ofHealth (NYSDOH) in accordance with a 1984 Memorandum ofUnderstanding. The remedial action consists of multiple remedial systems and programs that are designed to contain aqueous phase liquid (APL) and non-aqueous 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 ofthe 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.

A. S-Area Overburden Remedial Systems

The objectives established for the Overburden Remedial Systems are: (1) to contain APL and NAPL, (2) to maximize the collection ofNAPL, and (3) to minimize the migration ofchemicals toward the City's DWTP. The Overburden Remedial Systems consist of a slurry cut-offwall (Barrier Wall), a Drain Collection System (DCS), a network ofSite 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 ofthe designbetween 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 ofdrinking 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

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decommissioned. The replacement DWTP was fully operational by the end ofFebruary 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 System (DCS)

The DCS is comprised ofa network ofdrains located in overburden soils within the Barrier Wall and sloped to a central collection well (Wet Well A) for recovery ofgroundwater and NAPL. Each drain consists ofa perforated pipe located at the bottom ofa stone-filled trench. The DCS is designed to maximize the collection ofgroundwater 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 ofAPL 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 ofthe 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 ofpumping 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 gpmcould be achieved at Wet Well A and the water levels throughout most ofthe 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 ofthe 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 ofthe drain system. EPA and NYSDEC met with OCC and its contractors on Apri115, 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 ofthe quarterly sampling program. Recent monitoring indicates that the DCS is operating properly.

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Site Containment Purge Wells

The design ofthe Site Containment Purge Wells network was included as part ofthe 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 primping operations commenced in August 1996. Several 0 f the pumping wells were designated as NAPL recovery wells, based on the pump-testing results. The site containment purge wells and their effectiveness are monitored under the quarterly sampling program.

Capping

The purpose ofcapping the land:fi11 is to provide a physical barrier for the protection ofhuman health and the environment. It is also to minimize the infiltration ofprecipitation and, hence, the volume of leachate generated in overburden soils within the Barrier Wall. Reducing the volume of leachate within the land:fi11 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.

The site capping program consists of a Perimeter Cap and Land:fi11 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 ofthe 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 ofthe Parkway, along the Niagara River. EPA and NYSDEC approved the design ofthis phase ofthe Perimeter Cap construction on December 22, 1995. The Perimeter Cap is comprised of an asphalt cap (for parking) on the north and west perimeters ofthe land:fi11 and a composite liner on the south perimeter. The composite liner consists ofa 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 ofthe 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 Apri12002. This phase of the Perimeter Cap is discussed in further detail in the section which describes the remedial work performed in connection with the DWTP Remedial Program.

The Land:fi11 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, 6 inches oftopsoil and a vegetative cover. Construction ofthe cap began July

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2000; construction ofthe Landfill Cap was largely completed in October 2001 and the final inspection was conducted in May 2002. The cap is maintained by acc contractors. Maintenance includes mowing and repair ofthe fence.

B. S-Area Bedrock RRT System

The objectives for the Bedrock RRT System are: to hydraulically contain APL and NAPL within the existing area ofbedrock 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 ofthe more-highly fractured upper 30 feet of bedrock; (2) an Intermediate Bedrock Zone between the depths of approximately 30 and 100 feet below the top ofbedrock; and (3) a Deep Bedrock Zone between the depths ofapproximately 100 and 150 feet below the top of bedrock. To achieve these objectives, the Bedrock RRT System is comprised ofgroundwater pumping wells, NAPL recovery wells, and monitoring wells for each ofthe three zones. A network of force mains are used for piping leachate from the wells to the on-site Leachate Storage and Handling Facility.

The design, installation, operation and monitoring ofthe Bedrock RRT System was conducted in the three~phased approach described below.

Phase I - Initial Testing ofShallow Bedrock Zone

The Phase I design was included as part ofthe plans contained in Appendix I ofthe RRT Stipulation. The installation of the groundwater pumping wells and NAPL recovery wells commenced in November 1990. The wells were installed in the Shallow Bedrock Zone within the area ofthe defined NAPL plume. EPA approved the testing program for Phase I in June 1992. The purpose of the testing was to evaluate the capability ofthe wells to recover NAPL and the hydraulic properties ofthe fractured bedrock. Testing was performed from June 22, 1992 to October 2, 1992.

Phase II - Prototype Bedrock System

Based on the testing results for Phase I, the Prototype Bedrock System was designed for the Shallow, Intermediate and Deep Bedrock Zones. The design for the Shallow Bedrock Zone system consists of the existing groundwater pumping and NAPL recovery wells installed and tested as part ofPhase 1. EPA and NYSDEC approved the Prototype Bedrock System design for the Intermediate and Deep Zones on September 23, 1993. The installation of the Intermediate and Deep Bedrock wells commenced in late 1993. During the installation ofthose wells, NAPL was encountered in some areas of the bedrock which had not been previously identified, thus requiring the redefinition ofthe NAPL plumes and, subsequently, the redesign of the Prototype Bedrock System. The installation work for the pumping wells was substantially completed by early 1996. EPA and NYSDEC approved

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the force main designs for the Prototype Bedrock System on June 10, 1994. The force mains were installed in 1995. Operation ofthe Prototype Bedrock System commenced in July 1996.

Part ofthe effort to redefine the extent ofbedrock NAPL contamination included an investigation of NAPL at the former DWTP property (see also DWTP NAPL Investigation, below). The investigation and redefinition of NAPL presence within the bedrock zones at the DWTP were completed in July 1997. Based on the results ofthose efforts, additional pumping wells were installed in the Shallow and Intermediate Bedrock Zones in 1997. Force mains were constructed for the addition ofNAPL recovery wells in September and October 1998. Additional monitoring wells for the Shallow and Intermediate Zone were installed in 1999. Data collected during the operationofthe Prototype Bedrock System was used to design the final Bedrock RRT System.

Phase III - Bedrock RRT System

The Bedrock RRT System Design report was submitted to EPA and NYSDEC on February 9, 200l. It was determined that three new monitoring wells needed to be installed into the site and that three existing monitoring wells were to be converted to extraction wells. This action was completed June 2002. No further construction related to this phase is expected although system modification and maintenance occurs regularly.

The Landfill drainage systems are operating as designed based on the monitoring ofsite operations. The S-Area Overburden Remediation System currently contains the APL and NAPL. Collection of NAPL has been maximized as demonstrated by the conversion ofcertain monitoring wells into NAPL recovery wells and the subsequent increase in NAPL collection quantity. Migration ofcontaminants 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 ofthe inward gradients within the barrier wall.

The S-Area Bedrock System is complete and operational. Based on the monitoring data collected, 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 ~ithin each ofthose zones. The systems are operating as designed but minor alterations continue to be necessary to fully attain the inward and upward gradients ofthe site contamination called for in the agreements. .

As part ofthis effort, a NAPL Tracer Study is being conducted to determine whether the extraction of the NAPL mass is stopping the migration of the NAPL plume from migrating under the Niagara River. Presently, OCC is preparing a report which describes this effort to help determine ifsufficient information is available for EPA and NYSDEC to make this determination. Even though a substantial

. quantity of the NAPL mass is continually being removed from the site it has not been possible to observe directional changes of this NAPL body from the apex of this mass.,

In addition, further observation ofthe chemistry in the water existing in the remaining Intake Tunnel void will continue so as to assure the contamination does not rebound.

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C. Remedial Waste Management Program

The Remedial Waste Management Program is for the management ofall solid and semi-solid waste materials, APL, and NAPL generated during the construction and operation ofsite remedial activities. This program includes: (1) the disposal ofsolid and semi-solid remedial wastes atop the landfill; (2) construction of the Leachate Storage and Handling Facility; (3) construction ofa water treatment facility to treat APL chemicals (hereinafter the"APL Treatment Facility"); and (4) characterization 0 f S-Area NAPL and obtaining the authorization to incinerate S-Area NAPL at the Liquids Hazardous Waste Incinerator (Liquids Incinerator), located at acC's Buffalo Avenue Chemical Plant (note: this aspect ofthe program was modified to allow for the off-site incineration ofthe NAPL).

Remedial Waste Disposal

All solid and semi-solid waste materials generated during performance ofthe 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 ofeach other to accommodate waste placement and to match final grading plans for the landfill. The bottom ofthe 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. The facility includes five decanters for separating the leachate into APL and NAPL. The facility is also designed to hold six 158,OOO-gallon tanks for storing APL and NAPL, for a maximum storage capacity ofnearly one million gallons. Although the facility has the capacity to hold six tanks, three tanks were considered adequate at the time (two APL tanks and one NAPL tank) based on preliminary estimates ofleachate volumes to be generated by the remedial systems.

EPA and NYSDEC approved the civil engineering design for the Leachate Storage and Handling Facility in May 1991 and construction commenced on June 4, 1991. The electrical and mechanical engineering designs were approved by the end ofAugust 1991. 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 158,OOO-gallon 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.

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APL Treatment Facility

The APL Treatment Facility utilizes granular activated carbon for treating APL generated by the site's remedial systems. The maximum treatment capacity is approximately 300 gallons per minute (gpm) or roughly halfa million gallons per day (mgd). 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 actober 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. Discharges to the Niagara River have been within permitted requirements.

NAPL Characterization and Authorization to Incinerate

acc collected representative NAPL samples from the site in 1992 for characterization and to obt'ain authorization to incinerate. EPA and NYSDEC permitting authorities approved the burning of S­Area NAPL at acC's Liquids Incinerator in 1993. The results of trial burns conducted by acc in 1994 and 1995 indicated that the S-Area NAPL was a difficult waste to incinerate due to a high ash and chlorine content and a low BTU value. acc elected not to burn S-Area NAPL at the Liquids Incinerator, but continued to store it on-site while assessing the availability ofpermitted commercial incinerators. In 1999, acc began transporting the collectedNAPL to a RCRA-approved commercial incineration facility located in Deerpark, Texas: This facility has been utilized continually except for a period from April 2001 until November 2003, when the NAPL was treated at the acc Main Plant Liquids Incinerator. This plant was shut down by acc and the NAPL again shipped to the Texas facility. Presently, approximately 900 gallons ofNAPL per month are collected from the site and sent to the approved facility for incineration. To date, approximately 230,000 gallons ofNAPL have been collected and incinerated.

D. Drinking Water Treatment Plant (DWTP) Remedial Program

This program consists of the construction of a new DWTP 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 ofthe eastern portion ofthe 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 closure ofthe 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 acC's NAPL investigation.

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New Drinking Water Treatment Plant

For the siting ofthe new DWTP, the City selected a 25. 8-acre parcel ofland owned by the New York Power Authority (NYPA) and located adjacent to the fonner DWTP along Buffalo Avenue (hereinafter the "Buffalo Avenue site"). At that time, the Buffalo Avenue site was listed on the NYSDEC's Registry of Inactive 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 Avenue site to be relatively clean, with the exception ofa 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 ofland. The City completed acquisition of the Buffalo Avenue site from the NYPA on June 5, 1992.

In accordance with the RRT Stipulation, EPA and NYSDOH had approval authority ofthe DWTP design plans and specifications as they related to any systems and structures intended to prevent future contamination ofthe City's drinking water supply. As part ofthe 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 ofa 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 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 mgd, with a peak hydraulic capacity of52 mgd. Average daily demand in the early 1990's was approximately 25 mgd. Construction ofthe 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 of 2004 construction of drying beds used for processing the sludge regularly generated by the treatment ofdrinking water, volatile organic compound (VOC) contamination was discovered in the soils being excavated. This contaminated soil is being addressed by the DWTP facility and the contamination is not related to 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. The DWTP is operating and functioning as designed. It produces potable water for the City which meets all regulatory requirements and serves a population ofapproximately 62,000 people.

Demolition ofFormer Drinking Water Treatment Plant

The City's contractor commenced demolition ofthe fonner DWTP on April 3, 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

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plants prior to demolition and transported to the S-Area landfill for disposal in accordance with federal and state requirements for handling and disposal ofasbestos waste. The filter media was also removed from a filtration plant prior to demolition and disposed at the S-Area 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 ofthe wall. The plugging ofsevered utilities which lie outside of the eastern Barrier Wall with grout eliminates 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 ofthe Barrier Wall. With the completion ofthe eastern portion ofthe wall, all four sides ofthe Barrier Wall were completed. The barrier wall does not require maintenance and it's effectiveness is monitored under the S-Area Bedrock RRT System

APr 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 ofthe property. The collection system consists ofa perforated pipe located at the bottom ofa stone­filled 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 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 ofthe property. However, at that time, the Eastern Portion ofthe property had not been thoroughly investigated for S-Area chemicals. acc subsequently designed the system to include the Eastern Portion when S-Area chemicals were found there by the City during its investigation (see also Eastern Portion Study, below).

EPA and NYSDEC approved the design for the drain collection system on November 6, 1997. Construction commenced in Apri11998 with the severance and plugging ofabandoned utilities from the former DWTP that crossed the planned alignment of the drain. Construction of the drain collection system began in June 1998. The construction work was substantially complete in December 1998 and start-up operations commenced in Jaimary 1999. A breach found in the pipe during inspection was repaired in June 1999. The drain collection system is fully operational and functioning as designed.

NAPL Removal from Bedrock Raw Water Intake Tunnel

The purpose ofthe NAPL Removal Program is to inspect the bedrock raw water intake tunnel ofthe former DWTP for the presence ofNAPL, and remove any collectable quantities ofNAPL from the tunnel prior to grouting. In Apri11996, ace's contractor performed a video inspection of the first

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1,060 feet of the bedrock tunnel. The inspection revealed the presence of collectable quantities of NAPL 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.

Closure o(Raw Water Intake Structures

The purpose of this program is to seal up 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 closure ofthe bedrock intake tunnel network, including the two shaft intakes and shore shaft was performed by grouting the entire system with cementlbentonite grout. The bedrock tunnel is located over 70 feet below ground surface. It is approximately 6 feet wide, 7 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 ofthe Tunnel Grouting field activities occurred in July 2000. The grouting proceeded as designed with exception ofa portion ofthe tunnel underlying Buckhorn Island. It was confirmed by borings that the tunnel was grouted floor to ceiling for the majority ofthe extent ofthe tunnel with the exception ofa length oftunnel as described in more detail below. The construction equipment was demobilized in December 2000. It was subsequently demonstrated that over 90 percent ofthe tunnel has been properly grouted from floor to ceiling. Confirmatory drilling performed in accordance with the approved work plan has identified the void in the tunnel at a distance ofapproximately 3,800 feet from the shoreshaft. 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 ofthe tunnel and is being monitored as part of the bi-annual Shallow Bedrock Sampling Program. Low­level VOC contamination was detected in the void water but it could not be determined whether this contamination was a remnant ofthe grouting activities or was migrating from the local bedrock into the void.

It was decided at a May 2003 meeting to inject a solution ofsodium permanganate into the tunnel void and continue sampling. There have been three injections ofsodium permanganate into the tunnel void - the first in March 2004. The levels ofVOCs in the tunnel void have continued to decline and to rebound less with each subsequent treatment. The last two rounds ofsampling showed a reduction ofVOC levels to concentrations below maximum contaminant levels (MCLs). EPA and NYSDEC will continue to observe the tunnel void contamination data to determine if further treatment will be necessary.

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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 12 inches ofcompacted clay, 12 inches ofloam, 6 inches oftopsoil and a vegetative cover. The geomembrarie liner overlaps the top of the eastern Barrier Wall and abuts 53rd Street, the road separating the former D.WTP property from the S-Area 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 ofthis area is part ofthe 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 of New 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 ofcontamination and whether such contamination posed a threat to human health and the environment. The results revealed the presence ofS-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 ofthe Eastern Portion Study, the City also performed an investigation ofthe one­acre 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 addressed as part of the S-Area and not covered by this reVIew.

DWTP NAPL Investigation

During the installation ofthe S-Area Prototype Bedrock System monitoring wells in 1997, NAPL was encountered in an area ofthe bedrock at the former DWTP which was not previously identified. An investigation was performed by acc to redefine the extent ofNAPL chemicals. Bedrock wells were installed on both the western and eastern portions ofthe property. The results showed the presence of NAPL in the Shallow Bedrock Zone extending as a linear, "finger-like" feature eastward approximately 300 feet from the previously defined NAPL plume boundary. acc 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 hydraulically control the APL and NAPL plumes at this portion ofthe property and collect NAPL. Their operation continues to be evaluated dUring the implementation of the final Bedrock RRT System to fully attain the containment of this contamination. A hydraulic monitoring program has been initiated to evaluate the long-term

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effectiveness of this system in containing the APL plume at the fonner DWTP property. Two additional wells in this area were connected in 2006 into the extraction system and the evaluation of this investigation continues as part of the site-wide sampling program.

Operation and 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 perfonned voluntarily on an annual basis at 22 monitoring wells within the fonner city drinking water treatment plant (DWTP). Samples are analyzed for site-specific VOCs, semi-volatile organic compounds (SVOCs), pesticides, and organic acids, and total organic carbon (TOe) and total organic halides (TOX).

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

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

V. Progress Since the Last Five-Year Review

The last Five-Year Review, completed on Apri114, 2004, found the remedy to be protective.

During this five:-year reporting period, the semi-annual sampling ofthe site monitoring wells has been perfonned and regular maintenance ofthe remedial systems has been perfonned. At the time ofthe previous Five-Year Review for the site, the PRP had injected the first application of potassium pennanganate into the limited void in the fonner DWTP intake tunnel. Monitoring data from the well in this void had showed the presence of S-Area chemistry. OCC and the EPNState agreed to test chemical oxidation, via potassium pennanganate injection, in an attempt to mitigate this contamination. The third injection ofpotassium pennanganate was perfonned in January 2007. The continued semi-annual sampling of the water in this void has shown a decrease in contaminant concentrations following the injections with little rebound ofcontaminant concentrations, indicating that the potassium pennanganate injections have been effective in reducing the contamination within

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this void. This void will continue to be observed as part ofthe regular semi-annual sampling of the site.

The previous Five-Year Review identified a potential for the indoor air at the APLINAPL treatment plant to be contaminated. The treatment plant is regularly checked for such contamination under federal Operational Safety and Health Agency requirements and has been deemed to be safe for personnel operating the plant.

Also, in order to improve the extraction of APL and NAPL contamination from the site, EPA and NYSDEC approved a plan in the Fall of2006 to extend the Drain Collection System further into the northeastern portion of the site. This effort was completed in January 2007 and has successfully improved the inward and upward hydraulic gradients in that area.

VI. Five-Year Review Process

Administrative Components

The Five-Year Review team consisted ofKevin Willis (RPM) and Charles Nace (Human Health and Ecological Risk Assessor) of EPA, and Edward Modica (Hydrogeologist) of the United States Geological Survey.

Community Involvement

The EPA Community Involvement Coordinator (CIC) for the Hooker S-Area site, Michael Basile, published a notice in the Niagara Gazette on May 23,2009, notifying the community ofthe initiation ofthe Five-Year Review process. The notice indicated that EPA would be conducting a Five-Year Review ofthe remedy for the site to ensure that the implemented remedy remains protective ofpublic 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 the Five-Year Review are summarized in Table 2.

Data Review

Based on hydraulic data from recent monitoring reports, 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 ofNAPL observed in wells screened in the three bedrock zones, it appears that NAPL has not moved beyond the NAPL plume-limit boundaries that were established for the S-Area and that NAPL is contained within the S-Area. Environmental monitoring shows that, although there are site-related chemicals ofvarying concentrations in monitoring wells just outside the

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periphery ofthe site, these are similar to or less than the concentrations shown at start-up and indicate that migration ofAPL away from the site does not appear to be occurring. The water-quality results from intermediate bedrock wells OW693 and OW800, located along the Niagara River, show no contamination and suggest that APL is not migrating from the site below the river.

The ongoing DNAPL Tracer Study is presently being evaluated. The purpose of this study is to determine the effectiveness of DNAPL extraction within the barrier wall relative to the further downgradient migration ofthe DNAPL mass. OCC is presently producing an analysis report ofthe DNAPL Tracer effort that is expected to be submitted in the Spring of20l 0 for EPA and NYSDEC reVIew.

Site Inspection

A site inspection was conducted on March 30,2009. The following parties were in attendance:

Charles Nace, EPA, Ecological Risk Assessor John Pendlechuk, Conestoga-Rovers & Associates (PRP's consultant) Clint Babcock, Glen Springs Holdings (OCC Site Management Company)

VII. Technical Assessment

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

Based on an evaluation ofhydraulic and water-quality data collected since 2005, the remedy at the Hooker S-Area site appears to be functioning as intended by the decision documents. As descnbed in the Stipulation on Requisite Remedial Technology (RRT) of 1991, the remedy is containment - the objectives ofwhich are to prevent non-aqueous phase liquids (NAPL) and dissolved phase liquids (APL) in groundwater from migrating from the landfill to the Drinking Water Treatment Plant (DWTP) and into the Niagara River. The remedy consists ofS-Area Overburden Remedial Systems, a Bedrock RRT System, and a Remedial Waste Management Program.

The Overburden Remedial Systems includes a barrier wall, a drain collection system within the wall, site contaminant purge and recovery wells, and perimeter caps made of asphalt and composite material. The system functions to collect and contain APLINAPL, and 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 the S-Area landfill. Monitoring wells between shallow bedrock and overburden indicate upward gradients. The collection system appears to be in good repair and design flow rates have been achieved. Water-quality data show that, although there are site-related chemicals in monitoring wells in the V-Area just outside the periphery ofthe site, these are similar to or less than the concentrations shown at start-up and indicate that migration of APL away from the site does not appear to be occurring. The V-Area is being addressed under a corrective action program being administered by New York State under the authority of the Resource Conservation and Recovery Act.

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The Bedrock RRT System is comprised ofanetwork ofgroundwater pumping wells, NAPLrecovery wells, and monitoring wells for the shallow, intermediate, and deep bedrock zones. The purpose of the Bedrock RRT System is to hydraulically contain and collect APL/NAPL within existing area of bedrock NAPL plume, and to prevent NAPL migration in bedrock under the Niagara River. The system is design to remediate three distinct water bearing zones and achieve inward hydraulic gradients across existing plume boundary in each zone. Based on hydraulic data from recent monitoring reports, inward gradients have been consistently maintained in the shallow, intermediate, and deep bedrock zones relative to the area of the NAPL plumes. Further, the presence ofNAPL observed in wells screened in the three bedrock zones indicates that NAPL has not moved beyond the NAPL plume-limit boundaries that were established for the S-Area and that NAPL is generally contained within the S-Area. Environmental monitoring shows that, although there are site-related chemicals ofvarying concentrations in monitoring wells just outside the periphery ofthe site, these are similar to or less than the concentrations shown at start-up and indicate that migration ofAPL away from the site does not appear to be occurring. The water-quality results from intermediate bedrock wells OW693 and OW800, located along the Niagara River, show no contamination and suggest that APL is not migrating from the site below the river.

A Remedial Waste Management Program is in place to process and dispose of contaminated groundwater. Groundwater influent is conveyed to a treatment facility equipped with carbon adsorption system to treat APL. Treated water is discharged to the Niagara River in accordance with permit requirements. Leachate is conveyed to the storagelhandling facility and separated into APL and NAPL. The APIr undergoes treatment at on-site treatment facility; NAPL is characterized and sent to an off-site RCRA facility for incineration. All systems are routinely maintained according to Operation and Maintenance Plans and are functioning as designed.

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 - The decision documents and orders reviewed did not identifY exposure assumptions or toxicity data to evaluate potential risks and hazards associated with the site. The objective ofthe remedy is to contain the plume and prevent migration beyond the boundaries of the existing plume. Therefore, the Five-Year Review focuses on this objective.

As part ofthis Five-Year Review, EPA compared the groundwater cleanup goals selected in the 1990 ROD to current groundwater criteria. Although some ofthe 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 (denoted by a range) or below a hazard index of 1.0 (denoted by a single value) on EPA screening values, with the exception of mirex, hexachlorobenzene, hexachlorocyclohexane, and 2,3,7,8-TCDD. Although the cleanup value for these four chemicals are outside of the risk range, with the exception of2,3,7,8-TCDD, they are within the same order of magnitude. The cleanup goals that were chosen in 1990 remain valid in 2009, and the remedy remains protective ofhuman health (See Table 3).

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The 2004 Five-Year Review indicated that vapor intrusion was not a completed pathway due to the lack of buildings over the plume. Based on the site visit conducted in March 2009, the vapor intrusion pathway remains incomplete since no buildings are located over the plume. Future Five­Year Reviews should continue to evaluate this pathway buildings are constructed over the plume.

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 unclear if an ecological risk assessIJ;lent was conducted for the Hooker-S Area site. However, based on the implementation ofthe remedy, any potential pathways for ecological receptors have been eliminated through capping and groundwater control. Therefore based upon review ofthe past and current data, combined with the site visit, there are no completed exposure pathways for ecological receptors. The remedial action objectives used at the time ofthe remedy selection are still valid and protective ofthe environment.

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

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 call into question the protectiveness ofthe remedy.

VIII. Recommendations and Follow-Up Actions

This site has ongoing operation, maintenance and monitoring activities as part ofthe selected remedy. As was anticipated by the decision documents, these activities are subject to routine modification and adjustment. This report includes suggestions for improving, modifying, and/or adjusting these activities.

The site requires monitoring, operation, and maintenance activities to ensure the effectiveness ofthe remedy; acc 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 ofthe 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 ofAPL from 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 NAPL 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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IX. Protectiveness Statement

The remedy has been implemented and it has been determined that it is functioning as intended and remains fully protective ofhuman health and the environment.

x. Next Review

The next Five-Year Review for theHooker S-Area site should be completed within five years from the signature date below.

Approved:

Walter E. Mugdan, ector Emergency and Remedial Response Division EPA - Region 2

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Attachments:

Table 1 : Chronology of Site Events

Event Date

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

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

LSHF Construction Completion June 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 Start March 1995

APL Treatment Plant Final Inspection April 1995

DCS Construction Completion June 1995

Bedrock RRT 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

RA Construction Final Inspection October 1999

DCS Final Construction Completion March 2000

Landfill Cap Construction Start July 2000

Landfill Cap Final Inspection November 2001

Final Inspection of Site Construction Activities April 2002

Modification/Enhancement of Drain Collection System August 2006

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