EPA Superfund Record of Decision · specified in Nebraska Title 132 - Integrated Solid Waste...

EPA/ROD/R07-00/1072000

EPA Superfund

Record of Decision:

HASTINGS GROUND WATER CONTAMINATIONEPA ID: NED980862668OU 05HASTINGS, NE09/28/2000

SEP 28 2000MEMORANDUM

SUBJECT: Record of DecisionSouth Landfill subsiteOperable Unit #5 Hastings Ground Water Contamination SiteHastings, Nebraska

FROM: Paul Doherty, RPMIANE Branch

THRU: Glenn Curtis, ChiefIANE Branch

TO: Michael J. Sanderson, DirectorSUPR Division

Attached for your review and signature is the Record of Decision for the South Landfill Subsite.The Selected Remedy is Surface Water Controls and Geosynthetic Clay Liner Cap for Soil and LandfillContents, and Ground Water Use Restrictions and Natural Attenuation for Ground Water Remediation.The Selected Remedy is consistent with the preferred alternative presented in the Proposed Plan releasedon June 30, 2000.

Based on written and verbal comments submitted during the public comment period it wasdetermined that a change in the Proposed Plan was warranted. The source control remedy was modifiedto allow for the implementation of an alternative landfill cap design which meets the performance standardsspecified in Nebraska Title 132 - Integrated Solid Waste Management Regulations.

Also, it was determined that suitable biological activity and geochemical conditions are present andthat natural attenuation has the potential to successfully address the entire body of impacted groundwaterwith minimal site disruption. Based on this information, the selected remedy will be implemented as a finalremedy and not as an interim remedy as indicated in the Proposed Plan.

MEMORANDUM

SUBJECT: Record of DecisionSouth Landfill subsiteOperable Unit #5Hastings Ground Water Contamination SiteHastings, Nebraska

FROM: Paul Doherty, RPMIANE Branch

THRU: Glenn Curtis, ChiefIANE Branch

TO: Michael J. Sanderson, DirectorSUPR Division

Attached for your review and concurrence is the Record of Decision for the South Landfill Subsite.The Selected Remedy is Surface Water Controls and Geosynthetic Clay Liner Cap for Soil and LandfillContents, and Ground Water Use Restrictions and Natural Attenuation for Ground Water Remediation.The Selected Remedy is consistent with the preferred alternative presented in the Proposed Plan releasedon June 30, 2000.

Based on written and verbal comments submitted during the public comment period it wasdetermined that a significant change in the remedy was warranted. The source control remedy was modifiedto allow for the implementation of an alternative landfill cap design which meets the performance standardsspecified in Nebraska Title 132 - Integrated Solid Waste Management Regulations.

Also, it was determined that suitable biological activity and geochemical conditions are present andthat natural attenuation has the potential to successfully address the entire body of impacted ground waterwith minimal site disruption. Based on this information, the selected remedy will be implemented as a finalremedy and not as an interim remedy as indicated in the Proposed Plan.

Attachment

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION VII901 NORTH 5TH STREET

KANSAS CITY, KANSAS 66101

SEP 28 2000

MEMORANDUM

Attached for your review and signature is the Record of Decision for the South Landfill Subsite.The Selected Remedy is Surface Water Controls and Geosynthetic Clay Liner Cap for Soil and LandfillContents, and Ground Water Use Restrictions and Natural Attenuation for Ground Water Remediation.The Selected Remedy is consistent with the preferred alternative presented in the Proposed Plan releasedon June 30, 2000.

Based on written and verbal comments submitted during the public comment period it wasdetermined that a change in the Proposed Plan was warranted. The source control remedy was modifiedto allow for the implementation of an alternative landfill cap design which meets the performance standardsspecified in Nebraska Title 132 - Integrated Solid Waste Management Regulations.

Also, it was determined that suitable biological activity and geochemical conditions are present andthat natural attenuation has the potential to successfully address the entire body of impacted groundwaterwith minimal site disruption. Based on this information, the selected remedy will be implemented as a finalremedy and not as an interim remedy as indicated in the Proposed Plan.

Attachment

RECORD OF DECISIONDECLARATION

SITE NAME AND LOCATION

South Landfill SubsiteCERCLIS ID # NED980862668Operable Unit # 05Hastings Ground Water Contamination SiteHastings, Adams County, Nebraska

STATEMENT OF BASIS AND PURPOSE

The South Landfill Subsite, hereinafter referred to as the Site, is a subsite of the HastingsGround Water Contamination Site, Hastings, Nebraska. This decision document presents the selectedremedial action for source control and ground water remediation at the subsite. These actions werechosen in accordance with the Comprehensive Environmental Response, Compensation and LiabilityAct of 1980, as amended by the Superfund Amendments and Reauthorization Act of 1986, and, to theextent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan. Thisdecision is based on the Administrative Record file for this Site.

The state of Nebraska concurs with the selected remedy for this Site.

ASSESSMENT OF THE SITE

The response action selected in this Record of Decision (ROD) is necessary to protect thepublic health or welfare or the environment from actual or threatened releases of hazardous substancesin to the environment.

DESCRIPTION OF THE SELECTED REMEDY

This ROD describes remedial actions which address both source control and ground water.The source control remedy was developed to protect public health, welfare, and the environment byreducing migration of vadose zone contaminants (contaminants in the unsaturated soil overlying theaquifer) to the aquifer. The ground water remedy also was developed to protect public health, welfare,and the environment by controlling access to contaminated ground water while natural attenuationprocesses reduce the volume and mass of contaminants present in the ground water beneath and downgradient from the Site. These actions are consistent with all other planned Site response activities.

The major components of the selected remedy include:

< Surface Water Controls and Landfill Cover: The following actions will be taken:< Surface areas will be regraded to provide controlled drainage to an on-site drainage

way.

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< A geosynthetic clay liner (GCL) cap landfill cover will be installed that minimizesinfiltration of surface water and reduce contaminant migration.

< As an alternative to the GCL cap, an alternative cover may be installed in accordancewith landfill cover performance standards, as set forth in state regulations, as well as theFS remedy selection criteria.

A surface drainage system that quickly removes excess storm water, coupled with a landfillcover, will limit infiltration of surface water. This remedy would be implemented by first filling andre-contouring the existing ground surface to minimize surface water ponding, creating positive drainageof surface water run-off, and preventing erosion of the cover system. Regrading of the landfill surfacewill also accommodate future settling by overfilling areas that have subsided. Engineered controls will beutilized to minimize the risk to on-site workers and the community during construction activities at thelandfill.

The landfill cover will consist of a cap system designed to limit infiltration of surface water intounderlying waste. The cover system will control infiltration by use of either a low-permeability“infiltration layer” or by use of an alternative design which meets state performance standards for landfillcovers as set forth in Nebraska Title 132-Integrated Waste Management Regulations (Title 132),achieves ground water standards set forth in Nebraska Title 118-Water Quality Standards (Title 118),and satisfies the FS remedy selection criteria.

Surface water management controls would be implemented during the regrading of the landfillsurface. These controls would drain surface water flow from the landfill surface to the existing streamthat cuts through the Site.

A fence will be installed to control Site access. Deed restrictions will be imposed to restrict landuse. Ground water monitoring at the boundary of the South Landfill will be conducted to assess surfacecap effectiveness in reducing the migration of volatile organics into the aquifer.

< Ground Water Use Restrictions and Natural Attenuation: The following actionswill be taken:

< Ground water use restrictions will be put in place which will restrict installationof wells for drinking water purposes in areas suspected of ground watercontamination.

< Bio-chemical evaluation of the ground water regime will be conducted todetermine the effectiveness and dynamics of natural attenuation processes.

< Continued ground water monitoring for indicator parameters and constituentlevels in the impacted area will be performed to ensure that natural attenuationwill be effective in achieving cleanup goals within the 20-year project timeframe.

These actions employ institutional controls to protect potential receptors and an in situ treatmentapproach that addresses the entire body of impacted ground water, in contrast to a

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down gradient containment strategy. The ground water use restrictions will regulate current or futureproperty owners from pumping ground water for potable use until it is demonstrated through samplingthat the ground water meets drinking water standards. This measure minimizes the exposure pathway tocontaminated ground water.

Preliminary indications suggest that natural attenuation is reducing concentrations of chlorinatedvolatile organic chemicals (VOCs), which are the primary chemicals of concern (COCs), as groundwater migrates away from the Site. Chemical concentrations appear to be reduced down gradient fromthe Site suggesting that natural degradation, i.e., dispersion, adsorption and degradation, is occurring.

Implementing a natural attenuation approach to treat VOCs will involve sampling and analysisof ground water samples for natural attenuation indicator compounds and developing a conceptualmodel to describe the degradation mechanisms occurring. The remedial technology relies heavily onbiodegradation. Actual performance of the natural attenuation process will be closely monitored. Ifmonitoring data indicate that contaminant levels do not continue to decline as estimated in modelingpredictions, EPA in consultation with the Nebraska Department of Environmental Quality maydetermine that an alternative remedy should be implemented.

STATUTORY DETERMINATIONS

The selected remedy is protective of human health and the environment, complies with federaland state requirements that are applicable or relevant and appropriate to the remedial action, iscost-effective and utilizes permanent solutions and alternative treatment technologies to the maximumextent practicable.

The preamble to the National Contingency Plan (NCP) identifies municipal landfills as a type ofsite where treatment of the waste may be impracticable because of the size and heterogeneity of thecontents. Because treatment usually is impractical, EPA has developed “presumptive remedy” guidancewhich considers containment to be the appropriate response action for the source areas of municipallandfill sites. Based on the size and location of the landfill, EPA concluded that it was impractical toexcavate and treat the chemicals of concern in a cost-effective manner. Thus the remedy does notsatisfy the statutory preference for treatment as a principal element of the remedy.

Because this remedy will result in hazardous substances, pollutants, or contaminants remainingon-site above levels that allow for unlimited use and unrestricted exposure, a statutory review will beconducted within five years after initiation of remedial action to ensure that the remedy is, or will be,protective of human health and the environment.

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1 Geosynthetic Clay Liner Cap

2 The estimated costs are based on an assumed discount rate of 5% over 30 years

DATA CERTIFICATION CHECKLIST

The following information is included in the ROD:

< The COCs and maximum detected concentrations are:

COCS Maximum Detected Concentrations

• 1,1-dichloroethane 26 µg/l

• 1,1-dichloroethene (1,1-DCE) 29 µg/l

• cis-1,2-dichloroethene (cis-1,2-DCE) 94 µg/l

• trichloroethane 11 µg/l

• trichloroethylene (TCE) 300 µg/l

• tetrachloroethylene (PCE) 12 µg/l

• vinyl chloride (VC) 44 µg/l

< The baseline risk represented by the COCs are based on the contaminants detected inmonitoring wells at the Site. The EPA has established a Maximum Contaminant Level (MCL)for TCE, PCE, DCE, and VC. The MCL established for PCE and TCE is 5 micrograms perliter (µg/l); the MCL for cis-1,2-DCE is 70 µg/l, and the MCL for VC is 2 µg/l. The groundwater aquifer beneath the South Landfill has concentrations of these contaminants above theseMCLs.

< Cleanup goals established for the COCs are the MCLs or 1 x 10-6 cancer risk levels whichcorrespond to no more than an estimated one additional cancer case in a population of1,000,000 based on an assumed 30-year exposure period. Additional goals for the Site actioninclude prevention of further ground water quality degradation by eliminating further leaching ofcontaminants into the ground water via infiltration of surface water through the landfill contents.

< Deed restrictions will be imposed on the landfill property to restrict future land use. Current useof the ground water is restricted due to the contamination and pending institutional controls. Theselected remedy is designed to improve future use of the ground water by returning the groundwater to drinking water quality and making it suitable for all other beneficial uses. The estimatedcost of the selected remedy is:

Source Control Remedy1 Ground Water Remedy Total Project

Capital Cost $1,784,300 $108,000 $1,892,300

Annual O&M $21,147/year $32,000/year $53,147/year

Total Present Worth2 $2,109,300 $602,000 $2,711,300

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< The following were decisive factors that led to the selected remedy: • Overall protectiveness• Compliance with applicable, relevant, and appropriate requirements• Long-term effectiveness and permanence• Implementability • Cost • State support and acceptance• Community acceptance

Attachments: Decision SummaryResponsiveness SummaryAdministrative Record Index

RECORD OF DECISION

DECISION SUMMARY

HASTINGS GROUND WATER CONTAMINATION SITE

SOUTH LANDFILL SUBSITE

HASTINGS, NEBRASKA

Prepared by:

U.S. Environmental Protection Agency

Region VII

Kansas City, Kansas

September 29, 2000

Approved:

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Record of Decision

Decision SummaryContents

Section Page

Site Name, Location, and Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Site History and Enforcement Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Community Participation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Scope and Role of Response Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Site Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Current and Potential Future Site and Resource Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Summary of Site Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Remedial Action Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Description of Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Comparative Analysis of Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Selected Remedy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Statutory Determinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Documentation of Significant Changes from Proposed Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

1 - Figure from Remedial Investigation Report, South Landfill Subsite, Hastings Ground Water Contamination Site,Hastings, Nebraska, Morrison Knudson Corporation, December 1996.

2 - Figure from South Landfill Feasability Study, Hastings, Nebraska, ARCADIS Gerahty & Miller, Inc., April 2000.

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Record of Decision

Decision SummaryContents

List of Tables:

1. Soil Gas Sample Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52. Selected Ground Water Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63. Summary of Selected Chemical Toxicity Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84. Remedial Alternatives for Landfill and Landfill Soils . . . . . . . . . . . . . . . . . . . . . . . . . 115. Remedial Alternatives for Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146. Summary of Cost Estimates for Remedial Alternatives . . . . . . . . . . . . . . . . . . . . . . . 217. Summary of Comparative Analysis of Source Control Alternatives . . . . . . . . . . . . . 238. Summary of Comparative Analysis of Ground Water Remedy Alternatives . . . . . . . 24

List of Figures:

1. Hastings Ground Water Contamination Site Location Map1 . . . . . . . . . . . . . . . . . . 1-22. South Landfill Location Map2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-33. Site Plan1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14. Potentiometric Surface Map - October 19951 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

DECISION SUMMARYSOUTH LANDFILL SUBSITE

HASTINGS GROUND WATER CONTAMINATION SITE

SITE NAME, LOCATION, AND DESCRIPTION

Site Name: South Landfill SubsiteHastings Ground Water Contamination Site

Site Location: Hastings, Nebraska CERCLIS ID: # NED980862668Operable Unit: # 05Lead-Entity: EPA Site Type: Municipal Landfill and Contaminated Ground Water

The Environmental Protection Agency (EPA) has been investigating sources of ground watercontamination in the Hastings area since 1984. Due to the high levels of volatile organic compounds(VOCs) found in three municipal wells, the EPA designated the contaminated area as the HastingsGround Water Contamination Site (HGWCS). The HGWCS covers the central industrial area of thecity of Hastings and adjacent areas outside of the city limits. The HGWCS was placed on the NationalPriorities List in 1986. The National Priorities List is a nationwide list of hazardous waste sites that areeligible for investigation and remediation under the Superfund Program.

The Hastings South Landfill is one of seven subsites which make up the HGWCS (Figure 1).The HGWCS was divided into seven subsites for investigative and remediation purposes based ongeographic and constituent source area characteristics. The seven subsites which comprise theHGWCS are known as: the Former Naval Ammunition Depot, FAR-MAR-CO, North Landfill,Second Street, Colorado Avenue, Well Number 3, and South Landfill.

The South Landfill Subsite, hereinafter referred to as the Site, is approximately 56.2 acres insize and is located southeast of the central business district of Hastings. The Site is located in thesouthwest quadrant of Section 17, Township 7N, Range 9W, near the southeast border of the city ofHastings. The property is triangular in shape and is bounded by the abandoned Union Pacific Railroadright-of-way tracks on the south, the Good Samaritan Village retirement complex on the north,farmland on the east, and U.S. Highway 6 on the west. (Figure 2.)

The present day surface of the landfill is a relatively flat, grassy plane sloping gently from thenorthwest corner to the eastern boundary and southeastern corner. The ground surface of the Siteranges in elevation from approximately 1915 to 1900 feet above mean sea level. According to the city,the operation of active landfill activities ceased at the site in approximately 1984.

A concrete-lined drainage ditch bisects the landfill from north to south. According to the city,soil from nearby highway construction has been used to fill in low areas and provide a 1½ to 2-footcover over 22 acres of the Site. The landfill is partially fenced.

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SITE HISTORY AND ENFORCEMENT ACTIVITIES

The Site was originally a clay pit. Borrow operations ceased in the 1950s and the pit was thenabandoned. The Site was later operated as a municipal landfill by the city of Hastings from the early1960s to the early 1980s and accepted both municipal and industrial waste. The landfill wasconstructed with two main disposal cells. The western cell coincides roughly with the extent of the oldclay pit and was used from the early 1960s through the early 1970s. The eastern cell wasapproximately 400 to 600 feet wide and was situated along the eastern boundary of the South Landfill.This cell was used from the mid-1970s through the early 1980s. (Figure 3.) According to the city, theoperation of active landfill activities ceased in the early 1980s.

Subsurface investigations performed by U.S. EPA contractors beginning in the 1980s haveidentified potential impacts to ground water at the Site. EPA has directed a number of investigationsand seven monitoring wells have been installed within the boundaries of the Site. The EPA’sinvestigations have determined that wastes buried at the Site have contaminated and may continue tocontaminate the ground water beneath and down gradient and that the soil gas above the water table(vadose zone) also is contaminated with VOCs. Compounds detected include, but are not limited to: 1,1-dichloroethane (DCA), 1,1-dichloroethene (1,1-DCE), cis-1,2-dichloroethene (cis-1,2-DCE),trichloroethane (TCA), trichloroethylene (TCE), tetrachloroethylene (PCE), vinyl chloride (VC), andbenzene.

The VOCs are organic compounds that evaporate readily at room temperature. TCE andTCA were used as a degreasing solvents by metal finishing industries, as well as other industries. DCEand VC are biological breakdown products of TCE. l, l-DCA is a breakdown product of TCA.Benzene is a component of gasoline and was used as a general purpose solvent.

Potentially Responsible Parties (PRPs) are those individuals or corporations liable for the costsincurred by the EPA for investigation and cleanup of contamination at a Superfund site. In 1985, EPAconducted a PRP search and in September 1985, general notice letters were issued to the followingidentified PRPs: the city of Hastings, as operator of the landfill; Concrete Industries, as an owner of thelandfill; Dutton-Lainson Company and Dravo Corporation, as parties who arranged for the disposal ofhazardous substances at the landfill.

In January 1994, EPA notified the city of Hastings, Dutton-Lainson Company, DravoCorporation and Concrete Industries, Inc. of their potential liability for the Site, and advised them ofEPA’s decision not to invoke the Section 122(e) special notice procedures for the RemedialInvestigation/Feasibility Study (RI/FS). The EPA conducted the RI for the Site and issued the RIReport on December 27, 1996. On October 23, 1998, EPA entered into an Administrative Order onConsent with the city of Hastings, Dutton-Lainson Company, and Dravo Corporation to conduct theFS for the Site. The Nebraska Department of Environmental Quality (NDEQ) acted as the lead agencyin conducting oversight of the PRPs preparation of the FS. The EPA prepared an Addendum to the FSthat together with the FS and other documents in the Administrative Record provides the basis for theselected remedy. The EPA prepared and

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issued the Proposed Plan on June 30, 2000. The public comment period began on June 30, 2000, andended on August 30, 2000.

The EPA plans to issue Special Notice Letters to the above-named PRPs and expects to enterinto negotiations with the PRPs shortly thereafter for implementation of the remedial action. In addition,EPA is currently investigating additional PRPs for inclusion in its negotiations for the remedial action.

COMMUNITY PARTICIPATION

Community relations activities for the HGWCS were initiated by EPA in 1984. Earlycommunity relations activities included meeting with city and state officials to discuss the Site(December 1984), conducting interviews with local officials and interested residents (February 1985),establishing an information repository (February 1985), and preparing a Community Relations Plan(October 1985). Since December of 1984, EPA has conducted periodic meetings with Hastings cityofficials to update them regarding Site work, investigation findings, and to hear the city’s concernsabout the project. The Community Relations Plan was revised in January 1988 and again in January1990 to reflect new community concerns and Site activities.

Information on the Site, in the form of fact sheets, has been mailed to public officials, Hastings’businesses, and numerous citizens. The EPA held a public comment period from June 30 to August 30,2000, following the release of the Proposed Plan (June 30, 2000). The Proposed Plan identified thepreferred alternative to mitigate the contamination at the Site. On July 20, 2000, EPA held a publicmeeting to discuss the preferred alternative for the Site and to receive citizens’ comments andquestions. Agency responses to comments received during the public comment period are included inthe Responsiveness Summary attached to this Decision Summary.

SCOPE AND ROLE OF RESPONSE ACTION

This ROD addresses activities which will mitigate contaminant migration from the landfill sourceinto the ground water in the vicinity of the Site and will reduce contaminant mass in the ground water.The landfill wastes and contaminated soils underlyting the wastes are the source of contamination togroundwater at this Site. The purpose of the action for source control is to prevent the infiltration ofsurface water through the landfill by improvements to the landfill cap. The purpose of the action forground water is to restore the aquifer by reducing contaminant levels to below health based cleanuplevels.

This ROD is consistent, to the extent practicable, with the National Oil and HazardousSubstances Pollution Contingency Plan (NCP). In accordance with the NCP, the action for the Site willcomplement and be consistent, to the extent possible, with response actions underway, or planned, atthe other HGWCS subsites.

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The final action to be conducted at the HGWCS (including all subsites individually, either asseparate subsite actions or as part of an Area-Wide Remedy), will have a common goal to contain andremove contaminants in the ground water and reduce cancer risk levels to correspond to no more thanan estimated one additional cancer case in a population of 1,000,000 based on an assumed 30-yearexposure period. The goals for the South Landfill subsite action are to achieve safe drinking waterlevels (as defined by either the Safe Drinking Water Act maximum contaminant levels (MCLs) or 1 x10-6 excess cancer risk levels) and to prevent further ground water quality degradation by reducingfurther leaching of contaminants into the ground water via infiltration of surface water through the landfillcontents.

Private wells in the area of the Site have been sampled to ensure that human exposure tocontaminated ground water is not occurring. However, unrestricted water use, though it is not known tobe occurring, would pose an immediate threat to human health. Data in the RI Report indicate thatfurther remedial action is appropriate to prevent further degradation of the aquifer.

SITE CHARACTERISTICS

There are two aspects to the contamination problems at the South Landfill Site: the landfill, orsource area, and the underlying contaminated ground water. The landfill source includes both the landfillsurface and the subsurface soil above the underlying ground water, referred to as the vadose zone. Theground water includes the contaminated plume underlying the Site and extending off site.

Landfill Source Characteristics

The existing landfill cap has not been engineered to prevent subsidence problems or controlinfiltration through the landfill. Surface settling has occurred which has resulted in low areas anddepressions across the Site. Temporary ponding has been observed in low areas. Ponded water canprovide a driving force for infiltration of surface water into and through the land-filled material. Leachategenerated by the introduction of surface water into the body of the unlined landfill will migrate throughthe soil into the ground water.

The city has attempted to fill in low areas with fill and has constructed a concrete-lined drainageditch across the Site to improve surface drainage and help prevent erosion.

Table 1. shows the maximum concentrations of contaminants detected in soil-gas samples collected byEPA during 1986-1995. Soil-gas samples are an indicator of contaminants present in either thesubsurface soils or underlying ground water. There are no regulatory levels for soil-gas data.

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Ground Water Characteristics

During landfill operations, wastes containing VOCs, including chlorinated solvents, weredisposed in the landfill. These VOCs have since migrated vertically into the deeper vadose zone andhave entered the aquifer. Once the VOCs entered the aquifer, they migrated down gradient primarily inthe dominant direction of ground water flow (east-southeast).

Precise characterization of the groundwater contaminant plume is made difficult by thehighly transmissive nature of the underlying aquifer.Also, heavy seasonal ground water use cansubstantially alter the hydraulic flow patterns in theregion causing contaminant concentrations to varyseasonally.

While the present monitoring well networkis insufficient to fully characterize the extent of theplume, it does demonstrate that ground watercontamination has occurred at the Site. Data fromthe seven monitoring wells and eight productionwells depicted in Figure 4. were used tocharacterize and evaluate the Site.

TABLE 1.SOIL GAS SAMPLE DATA

Constituent

TCATCEPCE

HexaneHeptaneBenzeneXylene

MaximumConcentration

456 µg/l64 µg/l

222 µg/115 µg/l 14 µg/18.9 µg/l53 µg/l

Ground water sampling and analysis was performed in June, July, and October 1995 and againin January 1996. On-site monitoring wells (SL-1, SL-2, SL-3, SL-4, SL-4S, SL-4D, SL-5S, andSL-5D) were sampled during these four events. The July 1995 sampling event included three off-sitewells (M-20, I-47, and D-31). Data from other wells (IN-03, I-23, D-10, I-03, D-01, and I-47) wereobtained from prior sampling activity which occurred from 1988 to 1993. (Figure 4.)

Sampling results confirmed that ground water in the shallow wells (SL-2, SL-3, SL4S, andSL5S) was contaminated with VOCs. The upgradient well (SL-1) and the deep down gradient wells(SL4D and SL-5D) were essentially free of VOC contamination.

Contaminants in the shallow ground water beneath the landfill are mainly chlorinated solvents,including 1, 1-DCA, 1, 1-DCE, cis-1,2-DCE, TCE, PCE, and VC. TCE had the highest reportedconcentrations with 300 and 292 µ/l in wells SL-3 and SL-2, respectively. Cis-1,2-DCE was detectedat concentrations ranging from 5 µ/l to 94 µ/l and VC was detected at concentrations ranging from 16µ/l to 44 µ/l. Benzene was also detected in on-site wells, but at very low levels (0.2 µ/l to 0.8 µ/l).

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Detected concentrations of the identified compounds in the surrounding off-site wells that weresampled is minor. The majority of compounds detected were chlorinated solvents, which occurred atlow frequencies and low concentrations (0.9 µg/l to 6.0 µg/1). The range of concentrations observedfor the most significant compounds with their associated regulatory thresholds are summarized in Table2.

CURRENT AND POTENTIAL FUTURESITE AND RESOURCE USES

Land Use

The South Landfill property is currentlyowned and maintained by the city of Hastings.There are currently no activities occurring at theSite with the exception of routine maintenanceactivities (i.e., mowing) by the city. Currentland use of adjacent and surrounding propertyis mixed residential and agriculture. In the past,the city has used areas of the Site for disposalof excess soil from highway construction work.

Deed restrictions will be imposed onthe landfill property to restrict future land use tobe compatible with the selected remedy and afence will be installed to restrict unauthorizedaccess.

TABLE 2SELECTED GROUNDWATER DATA

Compound

1,1 -DCEcis-1,2-DCE

TCATCEPCEVC

DetectedConc. Range

3-29 µg/l4-94 µg/l1-11 µg/l

0.6-300 µg/l 0.0 -12 µg/l

1-44 µg/l

MCL(PRG)

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70200552

MCL - maximum contaminant levels (EPA Drinking WaterRegulations)PRG - preliminary remediation goals pg/1 - Micrograms per literNE - not established

Ground Water Uses

The ground water in the vicinity of the Site has been designated as a Class GA Ground WaterSupply by the state of Nebraska. A Class GA Ground Water is a ground water supply which iscurrently being used as a public drinking water supply or is proposed to be used as a public drinkingwater supply.

Contamination detected down gradient from the Site has caused the state to designate the Siteas a Remedial Action Class 1 (RAC-1) incident requiring “the most extensive remedial actionmeasures” to clean up the ground water to drinking water quality and suitable for all other beneficialuses.

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The city of Hastings is in the process of enacting an ordinance to restrict use of contaminatedground water for potable water purposes. These actions are necessary in order to minimize the threat tohuman health until such time as the project goals (i.e., MCLs) are achieved.

The proposed actions are necessary in order to ensure that the contaminated ground water iscleaned up and returned to full beneficial use within an acceptable time frame. Nebraska Title 118states that the time frame for required action (including cleanup) will be the period of potential exposureto the contamination in the absence of any remedial action or 20 years, whichever is less. On acase-by-case basis, a longer period of time may be allowed if adequately justified by the responsibleparty.

SUMMARY OF SITE RISKS

Superfund requires EPA to seek permanent solutions to protect human health and theenvironment from hazardous substances. These solutions provide for removal, treatment, orcontainment of dangerous chemicals so that any remaining contamination does not pose anunacceptable health risk to anyone who might come into contact with them. An ecological riskassessment was not performed because of the absence of surface exposure threats to ecologicalreceptors.

The EPA concluded that four chemicals (VC, PCE, TCE, and DCE) in the ground water at theSite might pose an unacceptable cancer risk to residents who use the ground water. This was based onthe determination that the most likely way in which the community might come into contact withSite-related chemicals would be if residents living near the Site might be exposed to contaminants inground water, if they drink ground water, come into direct contact with the ground water while bathing,or inhale ground water vapors while showering.

In November 1997, the Human Health Baseline Risk Assessment for the HGWCS, wasprepared by the Nebraska Health and Human Services System. The Baseline Risk Assessment (BRA)evaluated the area-wide risk associated with human exposure to ground water chemicals that remainafter subsite goals are achieved (i.e., subsite action would clean up the ground water to Drinking WaterHealth Advisory Levels [DWHALS]). DWHALS are nonregulatory guidelines that generally representconcentrations of carcinogens corresponding to 1 x 10-4 excess lifetime cancer risk. The BRA wasintended to assess the incremental risk of exposure to ground water with contaminant levels betweenthe DWHALs and final project remediation goals or MCLs.

The BRA evaluated the COCs for the Site in terms of “excess cancer risk” or the number ofadditional cases above the average number of cases that are expected to occur in the generalpopulation if the chemicals are not present. The EPA’s goal is to reduce the risk of cancer fromchemical exposure to a level equivalent to one additional case of cancer for every 1,000,000 (10-6)people exposed to it over a 30-year period. The BRA determined that exposure to these contaminants(TCE, PCE, DCE, and VC) might lead to unacceptable cancer risk.

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TABLE 3.SUMMARY OF SELECTED CHEMICAL TOXICITY DATA

Compound Toxicity

Vinyl Chloride VC is mutagenic and carcinogenic. It is classified as a known humancarcinogen (Group A) by EPA. VC can enter the body throughinhalation of vapors or ingestion of contaminated food or water.Acute exposure to VC may cause central nervous systemdepression. Chronic effects include loss of bone from fingers andtoes, circulatory disturbances and adverse effects on the skin, blood,lung, and liver.

Tetrachloethylene The classification of PCE as a carcinogen is under review by EPA.Non-carcinogenic effects of PCE include irritation to the eyes, noseand throat, finger tremors, flushed face and neck, vertigo, dizziness,skin erythema, liver damage and mental confusion. Chronicexposure may lead to irreversible damage of the liver, kidneys, eyes,upper respiratory system and central nervous system.

Trichloroethylene EPA has classified TCE as a probable human carcinogen (GroupB-2). Acute exposure to TCE may cause headaches, vertigo, visualdisturbance, tremors, nausea, vomiting, eye irritation, dermatitis,cardiac arrhythmia, and paresthesia. Chronic exposure mayirreversibly damage the respiratory system, heart, liver, kidneys, andcentral nervous system.

Dichloroethylene EPA has not classified DCE (cis and trans) as a human carcinogen(Group D). Acute exposure to DCE will have similar effects as acuteexposure to TCE.

In addition to estimating potential carcinogenic health effects, the BRA evaluated potentialnon-carcinogenic health effects caused by Site-related chemicals. Non-carcinogenic health effects arebased upon contaminant concentrations and are given a Hazard Index Rating (HI). Compounds with HIratings greater than or equal to one would pose a health risk whereas those less than one would notpose a health risk. The BRA determined that the HI rating for the Site is 2.54. Table 3 summarizessome of the available toxicity information for the chemicals of concern.

Pursuant to the authority of the Safe Drinking Water Act, (SDWA), 42 U.S.C. Section 300(g),EPA has established a MCL for TCE, DCE, and VC. The MCL refers to the maximum permissiblelevel of a contaminant in water which is delivered to any user of a public water system. The MCLs arebased on health risk, treatment technology, cost, and analytical methods and are used in developingground water cleanup levels. The MCLs established for the COCs for the Site are listed in Table 2.The ground water aquifer beneath the South Landfill has concentrations of these contaminants abovethese MCLs which has prompted EPA to consider

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institutional controls to reduce the risk levels while natural attenuation processes act to reducecontaminant concentrations to acceptable levels. For a more detailed description of risk to humanhealth and the environment, refer to the BRA which is contained in the administrative record.

The response action selected in this ROD is necessary to protect the public health or welfare orthe environment from actual or threatened releases of hazardous substances into the environment.

REMEDIAL ACTION OBJECTIVES

The remedial action objectives for this project are to:

• Restore the aquifer to drinking water standards within a reasonable (20 year) time frame.

• Control landfill surface water runoff and erosion.

• Reduce or eliminate further contamination of ground water.

• Minimize or eliminate contaminant migration to the ground water and surface water to levelsthat ensure the beneficial reuse of the resources.

The preliminary remediation goals for the chemicals of concern are based on the MCLsestablished under the SDWA.

DESCRIPTION OF ALTERNATIVES

Presumptive Remedies

The presumptive remedy guidance issued by the U.S. EPA for municipal landfills applies to theSite. Remedial alternatives presented in the FS Report and FS Addendum have therefore beenevaluated following the procedures defined in U.S. EPA “Presumptive Remedy for CERCLAMunicipal Landfill Sites” (U.S. EPA 1993a) (Presumptive Remedy Guidance). Use of the presumptiveremedy eliminates the need for the identification and screening of the complete range of conventionaltechnologies for various media. If a site meets the established site-type classification for which apresumptive remedy has been developed, the outlined approach can be followed to streamline theprocess for the analysis of technologies and alternatives to select a remedy for the Site. This allows fora more focused FS, considering technologies and approaches that have been proven. As presented inthe FS Analysis for CERCLA Municipal Landfills (U.S. EPA 1993b), containment is the presumptiveremedy for landfill contents and soil at municipal landfills.

In accordance with the municipal landfill guidance, the presumptive remedy for municipallandfills is containment within the source area. Therefore, the identification and

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screening of technologies has been streamlined as it relates to media within the source area. In addition,the use of presumptive remedies for municipal landfills eliminates the need for detailed discussion inother sections of the FS (e.g., development of remediation goals for on-site soils can be eliminated if thepresumption is that the Site will be capped and on-site soils will be covered).

Remedial Alternatives for the Landfill and Landfill Soil

Remedial alternatives for the landfill and landfill soil are summarized in Table 4. The alternativesare numbered to correspond with the numbers in the FS Report and FS Addendum. Alternative S-5 isa cap design recommended by the NDEQ which the state and EPA believe will comply fully withNDEQ’s Title 132. Alternative S-5 was not evaluated in the FS Report but is discussed in detail in theFS Addendum prepared by the U.S. EPA and NDEQ.

Alternatives S-1 and G-1: No Actions

Estimated Capital Cost: $0

Estimated Annual O&M: $0

Estimated Present Worth: $0

Regulations governing the Superfund Program require that the no action alternative be evaluatedat every site to establish a baseline for comparison. Under the no action alternatives, EPA would takeno action at the Site to prevent exposure to the ground water contamination. The Site would remain inits present condition. The potential for exposure to the community to contaminant levels exceedinghealth standards would remain.

Alternative S-2: Surface Water Controls and Clay and Soil Cap

Estimated Capital Cost: $2,097,000

Estimated Annual O&M: $19,000/yr

Estimated Present Worth: $2,394,000

Surface Water Controls: Surface water flow over or infiltration through the contaminated media canpromote the migration of contaminants from soil to water. Surface water controls are measures tocontrol run-on and run-off at the Site. Surface grading and diversion structures are proposed incombination with various capping options to eliminate low-lying areas susceptible to ponding ofrainwater and reduce infiltration.

Institutional Controls: For all landfill cap options, a permanent notation on the deed to the disposal areaproperty shall be recorded in the permanent records of the County Register of Deeds. This notationshall include the following information: the existence of a solid waste disposal area; the type, depth, andlocation of the waste; the existence of any monitoring systems; and any restrictions on the use of theproperty to protect the integrity of the final cover and monitoring systems.

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Landfill Gas Controls: Landfill gascollection systems are often needed inconjunction with a cap. The need for landfill gascontrols will be evaluated during the design ofthe cap and will be implemented if needed.

Clay and Soil Capping: Capping is a remedialtechnology which involves constructing a coverover buried waste and in-place soils. Thisserves to reduce the infiltration ofprecipitation and promotes surface-water runoff, thereby reducing leaching of contaminants.A cap also minimizes potential direct exposurepathways for human contact.

Table 4.REMEDIAL ALTERNATIVES FORTHE LANDFILL AND LANDFILL

SOILS

S-1 No Action

S-2 Surface Water Controls andClay and Soil Cap

S-3 Surface Water Controls andPhytocap

S-4 Surface Water Controls andComposite Cap

S-5 Surface Water Controls andGeo-Synthetic Clay Liner

Clay capping is a single-layer capping alternative. Clay is also the most expensive of thecapping options.

Alternative S-3: Surface Water Controls and Phytocap




Surface water controls and institutional controls for this alternative are the same as described inAlternative S-2.

A phytocap consists of a vegetated cover system over the landfill. At the South Landfill Site, thephytocap would have the primary function of minimizing surface water infiltration. To accomplish this,plants that take up large quantities of water (phreatophytic), would be utilized. Based on the relativelythin layer of fill over the landfill contents, grasses and shallow-rooted vegetation may be mostappropriate at the Site.

A phytocap design would be considered an alternative cap design under Nebraska’s Title 132- Integrated Solid Waste Management Regulations, Chapter 3, 005.01B. This regulation requires analternative design to provide “equivalent reduction” in infiltration and “equivalent protection” from windand water erosion as traditional designs specified in 005.01A

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Alternative S-4: Surface Water Controls and Composite Cap

Estimated Capital Cost: not evaluated in the FS

Estimated Annual O&M: not evaluated in the FS

Estimated Present Worth: not evaluated in the FS

Surface water controls and institutional controls are the same as described in Alternative S-2.

The composite cap is a multi-layer design generally consisting of the following components: abottom clay layer covered by a synthetic membrane, overlain by a drainage layer, and capped with atopsoil/erosion layer and vegetative cover.

The composite barrier cap is an accepted remedial containment technology which is effective inminimizing the infiltration of precipitation and exposure to affected media. Capital costs are estimated torange from moderate to high. Annual O&M costs are estimated to be moderate.

Although the composite cap is considered an effective containment option, it was not selectedfor detailed evaluation in the FS. For this reason, detailed cost information is not available.

Alternative S-5: Surface Water Controls and Geosynthetic Clay Liner (GCL ) Cap

It is the position of EPA and NDEQ that a geosynthetic design is a practical capping option forthe Site. The EPA and NDEQ prepared an Addendum to the FS which corrects deficiencies andoversights in the FS. The Addendum includes a detailed evaluation of a specific type of single-layerdesign, the geosynthetic clay liner cap, which is summarized below:




Surface water controls and institutional controls are the same as described in Alternative S-2.

The GCL cap design is a single-layer cap that is effective in minimizing infiltration and exposureto the landfill contents. The configuration from bottom to top consists of the following: 18” of soil withno permeability standard required to be used as a foundation layer for the GCL, a GCL layer with apermeability of 1 X 10-9 cm/sec to meet the permeability standard for the 18” infiltration layer requiredby Title 132, Chapter 3, 005.01A and an 18” erosion layer capable of sustaining vegetative cover.

Placement of the GCL cap design involves fewer construction quality assurance activities inrelation to the clay and soil cap and the composite cap. Permeability testing of the soil layers

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would be eliminated as the bentonite in the GCL material provides the necessary permeability. Seamtesting would also be eliminated as the GCL panels are overlapped and sealed with the placement ofadditional bentonite material. Low capital costs are associated with the construction of the GCL cap.Low O&M costs are also incurred as the erosion layer inspection, maintenance, and repair activitieswould be similar to other single-layer caps.

The GCL cap is administratively implementable and is an accepted remedial containmenttechnology which is effective in minimizing the infiltration of precipitation and exposure to affectedmedia.

Remedial Alternatives for Ground Water

Remedial alternatives for ground water are summarized in Table 5. The alternatives arenumbered to correspond with the numbers in the FS Report and FS Addendum.

Alternative G-2: Ground Water Use Restrictions, Hydraulic Containment Using VerticalExtraction Wells and Discharge to an Off-Site Facility

Estimated Capital Cost: $147,000


Estimated Present Worth: $654,000

Ground Water Use Restriction: Ground water use restrictions will be implemented through the use ofinstitutional controls. Institutional controls generally address a site risk by eliminating an exposure route,in contrast to removing the source or hazard. While institutional controls may be implemented on astand-alone basis, they can also be incorporated in conjunction with other remedial strategies.

Access restrictions with regard to ground water refer to limitations on extraction and usage ofground water for activities that present exposure, such as for drinking water. The city has taken initialsteps in proposing a institutional control area. Through this measure, the city of Hastings andneighboring authorities would enact a zoning ordinance requiring an application process for privatewells. The proposed ordinance will prevent installation of new domestic wells in the institutional controlarea, which includes the landfill property. Other types of water wells, such as irrigation and industrialwells, may be installed in the institutional control area but only after obtaining a permit. Existing drinkingwells in the impacted area will be assessed and may be removed from use, if necessary.

Ground water monitoring is proposed in combination with institutional controls. A sampling andanalysis program will be implemented to monitor the condition of the aquifer beneath and adjacent tothe Site. Existing monitoring wells will be selected for periodic sampling for appropriate parameters. Itis anticipated that additional off-site monitoring wells would be installed to monitor potential migration ofground water impact. In the event that additional sampling results in the detection of contamination in adrinking water supply above MCL levels, the affected residents will be offered an alternative watersupply until the ground water is remediated.

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TABLE 5.REMEDIAL ALTERNATIVES

FOR GROUND WATER

G-1 No Action

G-2 Ground Water Use Restrictions, Hydraulic Containment Using Vertical ExtractionWells and Discharge to Off-Site Facility

G-3 Ground Water Use Restrictions and Chemical Containment Using Sparge Curtain

G-4 Ground Water Use Restrictions, Hydraulic Containment Using Vertical ExtractionWells, Treatment by Carbon Adsorption, and Discharge to On-Site Stream

G-5 Ground Water Use Restrictions and Natural Attenuation

Hydraulic Containment: Hydraulic barriers consist of a series of wells where ground water is extractedto maintain a hydraulic gradient toward the wells (zone of influence). The maintenance of a hydraulicgradient controls migration of contaminants within the zone of influence. By installing the extraction wellcurtain throughout the impacted plume, the contaminated plume can be contained and remediated.

This alternative proposes to transport extracted water without prior treatment to a suitableremote facility, such as the city’s wastewater treatment facility, for disposal or a location where thewater can be used for beneficial use without presenting an unacceptable risk to human or environmentalreceptors. An example of this is the use of pumped water for irrigation or for recirculating cooling waterin industrial processes. The pumped ground water may be piped to the receiving facility.

Alternative G-3: Ground Water Use Restrictions and Containment Using SpargeCurtain




This alternative includes the Ground Water Use Restrictions as described for Alternative G-2.

Containment is a remedial technology whereby the migration of contaminants is controlled. Airsparging is a remedial technique through which air is injected into the saturated zone below the depth ofimpact. As the air bubbles rise through the horizon of impacted ground water, VOCs are stripped fromthe ground water and carried to the unsaturated zone in vapor phase. A soil vapor extraction (SVE)system collects vapors through wells installed above the saturated zone. In this manner, VOCs arestripped from the ground water, extracted via SVE wells, and treated above ground.

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Application of air sparging technology to the sparge curtain option involves aligning a networkof sparge (injection) points and associated SVE wells along the down gradient edge of the impactedground water. As ground water follows its natural course, the sparge curtain serves as an in situflow-through treatment system, removing VOCs from the ground water, without significantly altering theground water movement.

Alternative G-4: Ground Water Use Restrictions, Hydraulic Containment Using VerticalExtraction Wells and Treatment by Carbon Absorption with Dischargeto an On-Site Stream




The Ground Water Use Restrictions are the same as described in Alternative G-2.

Use of extraction wells is the same as Alternative G-3.

Physical treatment alternatives encompass a wide range of technologies which serve to modifythe physical state of the waste or contaminated media, or which rely on physical properties to alter thechemical make-up of the media.

Activated carbon adsorption is a physical treatment option wherein substances in an aqueouswaste stream are attracted to and adsorb to the surface of an activated carbon granule by physicaland/or chemical forces, This physical treatment option is a proven technology that is incorporated intomany treatment programs. Activated carbon adsorption could be effective for treatment of groundwater at the Site.

Carbon adsorption treatment can produce water quality suitable for surface water discharge.The intermittent stream that bisects the Site is a potential discharge location.

Alternative G-5: Ground Water Use Restrictions and Natural Attenuation



Estimated Present Worth: $602,000

The Ground Water Use Restrictions are the same as described in Alternative G-2.

Natural attenuation is an alternative which relies on the effectiveness of natural biological,geological, and chemical processes that result in the elimination of organic compounds. TCE and otherorganic compounds can be degraded, or destroyed, through a variety of naturally occurring chemicaland biological processes. Based on limited ground water

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sampling information, there is evidence to support a finding that natural attenuation processes arepresent and are degrading chlorinated organics at the Site. Data collected from the nearby NorthLandfill Subsite would also support a conclusion that natural attenuation processes are effective inreducing contamination in the aquifer. Implementation of natural attenuation will involve continuedmonitoring for contaminant concentrations and for natural biological and chemical parameters.

COMPARATIVE ANALYSIS OF ALTERNATIVES

Nine criteria are used to evaluate the different remediation alternatives individually and againsteach other in order to select a remedy. The nine evaluation criteria are (1) overall protection of humanhealth and the environment; (2) compliance with applicable, relevant, and appropriate requirements(ARARs); (3) long-term effectiveness and permanence; 4) reduction of toxicity, mobility, or volume ofcontaminants through treatment; (5) short-term effectiveness; (6) implementability; (7) cost; (8)state/support agency acceptance; and (9) community acceptance. This section of the ROD profiles therelative performance of each alternative against. the nine criteria, noting how it compares to the otheroptions under consideration. The nine evaluation criteria are discussed below. The “Detailed Analysis ofAlternatives” can be found in the FS Report and FS Addendum.

1 . Overall Protection of Human Health and the Environment determines whether analternative eliminates, reduces, or controls threats to public health and the environmentthrough institutional controls, engineering controls, or treatment.

All of the alternatives except the no action alternatives could provide adequate protection ofhuman health and the environment by eliminating, reducing, or controlling risk by one or more of thefollowing: through treatment, engineering controls, and institutional controls.

The installation of a GCL cap over the landfill areas provides a nominally greater degree ofprotection from both on-site soil and landfill contents and ground water than either a clay and soil capor a phytocap which are designed to meet a higher permeability standard.

An alternative cover design is presumed to be protective if it meets the equivalent reduction andequivalent protection standards as specified in Nebraska Title 132 - Integrated Solid WasteRegulations Chapter 3, 005.01B.

While the soil and fill material do not apparently present a risk, additional cover materialprovides another layer of assurance to reduce the risk presented by soil or soil gases. Moreimportantly, the caps will minimize storm water infiltration through the landfill contents and resultantmigration to ground water. Because it is presumed that landfill leachate is the primary source of groundwater impacts, a capping alternative will minimize the influence of leachate to the aquifer. No action, incontrast, will not prevent or reduce risks presented by the soil or ground water, and, therefore, is lessprotective.

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Alternative G-2, ground water use restrictions/hydraulic containment/off-site disposal wasconsidered to be the most protective overall. The ground water use restriction protects receptors fromexposure to ground water; hydraulic containment captures all potentially impacted ground water beforeit leaves the Site; and the off-site disposal of collected water entirely removes the potential source ofrisk from the Site. Similarly, Alternative G-4 (ground water use restrictions/hydrauliccontainment/on-site treatment/stream discharge) provides the second highest level of protection,differing from G-2 only in that ground water treatment is performed on Site, which introduces apotential element of risk to Site receptors. Alternative G-3, ground water use restrictions/chemicalcontainment with air sparging/on-site vapor treatment differs from G-4 only in the method ofcontainment. Due to channelization of air bubbles, insufficient contact to effect constituent transfer fromdissolved-phase to vapor-phase, and difficulty in assuring complete coverage, air sparging does notprovide as high a level of certainty of capturing constituents as ground water extraction. Fourthly,Alternative G-5, ground water use restrictions/natural attenuation provides sufficient protection forpotential receptors but at a potentially lower rate of remediation than the other alternatives. Theeffectiveness of natural attenuation also depends on specific subsurface conditions which must bepresent. Lastly, no action does not provide adequate protection because it does not prevent exposureto on-site and off-site ground water, which does exceed risk-based levels.

Because the no action alternatives (S-1 and G-1) are not protective of human health and theenvironment, they are eliminated from consideration under the remaining eight criteria.

2. Compliance with ARARs evaluates whether the alternative meets federal and stateenvironmental statutes, regulations, and other requirements that pertain to the site orwhether a waiver is justified.

The EPA assesses whether the remedial alternatives being evaluated will comply with allARARs. The substantive requirements of Nebraska Title 118 – Ground Water Quality Standards andUse Classification Chapter 10 and Appendix A are applicable at this Site. In accordance with Title118, Chapter 10, 001, the Ground Water Remedial Action Protocol found in Appendix A shall applywhen a point source pollution event has caused or will cause, in the NDEQ’s judgment, ground waterpollution. Step 8 of the Protocol establishes a method for determining preliminary cleanup levels for thedifferent classifications of protected ground water. The ground water in the vicinity of the Site has beendesignated as a Class GA Ground Water Supply by the state of Nebraska. Class GA Ground Water isa ground water supply which is currently being used as a public drinking water supply or is proposed tobe used as a public drinking water supply. Contamination detected down gradient from the Site hascaused the state to designate the Site as a RAC-1 incident requiring “the most extensive remedial actionmeasures” to clean up the ground water to drinking water quality and suitable for all other beneficialuses. Therefore, the cleanup level governing the ground water remedial options is the achievement ofMCLs or, if there is no established MCL, 1 x 10-6 risk level.

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However, the substantive Resource Conservation and Recovery Act (RCRA) and NebraskaTitle 132 – Integrated Solid Waste Management Regulations closure and post closure requirements areARARs at this Site. The selected remedy is necessary to provide the source control to minimize furtherinfiltration of contaminants to the ground water at levels exceeding the MCLs or 1 x 10-6 risk level.

The EPA expects that ground water clean up levels will be attained over all portions of theaquifer beyond the landfill boundary at the completion of the remedy. All ground water remedies thatreturn off-site ground water to drinking water quality are ARAR-compliant. The three cappingalternatives are expected to result in improved ground water quality by limiting the migration of leachateto ground water. Alternatives S-5 and S-2 are traditional designs which meet Nebraska Title 132 -Integrated Solid Waste Regulations. The phytocap design is considered to be an alternative final coverdesign that would require further information and evaluation before receiving approval. An alternativecover design could be considered compliant with ARARs if it meets the equivalent reduction andequivalent protection standards as specified in Nebraska Title 132 and the ground water protectionstandards of Nebraska Title 118.

3. Long-term Effectiveness and Permanence considers the ability of an alternative tomaintain protection of human health and the environment over time.

As with overall protection, the GCL cap is more effective than either the clay cap or thephytocap in reducing risk.

An alternative cover design could be considered effective if it meets the equivalent reductionand equivalent protection standards specified in Nebraska Title-132 and the ground water protectionstandards of Nebraska Title- 118.

As an in situ remediation approach, Alternative G-5 has the potential to continually reduceconstituent concentrations and, in the long-term, can potentially be the most effective. Alternatives G-2,G-3, and G-4 are all equally effective in that they prohibit off-site migration of impacted ground water.As stated previously, these three alternatives are passive systems that collect or treat ground water as itpasses through the ground water extraction zone or sparge curtain. Subsequently, mass removal ratesare typically low, limited by the aquifers ability to flush contaminants into the ground water regime.These alternatives provide long-term effectiveness while they are operating.

4. Reduction of Toxicity, Mobility, or Volume of Contaminants through Treatmentevaluates an alternative’s use of treatment to reduce the harmful effects of principalcontaminants, their ability to move in the environment, and the amount of contamination present.

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Although the capping alternatives do not reduce the volume or toxicity of the contaminationthrough treatment, the caps do reduce mobility of the constituents in the soil and fill. Because infiltratingwater is the presumed carrier of the constituents from the soil to the aquifer, the cap reduces mobility ofthe constituents by reducing the volume of water leaching through the landfill. As with overall protection,the GCL cap is more effective than either the clay cap or the Phytocap in reducing infiltration.

An alternative cover design could provide a comparable reduction in contaminant mobility if itmeets the standards specified in Nebraska Title 132 and the ground water protection standards ofNebraska Title-118.

Alternatives G-2, G-3, and G-4 are the most effective in reducing toxicity, mobility, or volumeof contaminants as they employ active remediation. Alternative G-5 has the potential to continuallyreduce constituent concentrations and can potentially be the most effective in the long-term.

5. Short-Term Effectiveness considers the length of time needed to implement analternative and the risks the alternative poses to workers, residents, and the environmentduring implementation.

In terms of short-term effectiveness, the soil alternatives are equal. The soil and landfill contentsdo not currently present a risk to receptors. In the short term, cap construction would result in minimaldisturbance to existing soil and fill, presenting a nominal increase in the potential for risk. Scarifying theexisting surface, confirming the extent of waste material with soil probes, and general activity at the Sitewould slightly increase the short-term risk.

In evaluating short-term effectiveness, the negative drawbacks of an option, including hazardsincurred due to the implementation of a remedy, are considered to assist in a cost/benefit assessment.Each of the remedial alternatives would be implemented to minimize any potential increase in riskpresented by drilling activities, ground water sampling, and extraction/treatment operation. Personalprotective equipment and other health and safety measures would be implemented to protectremediation workers from such exposure. Further, it is not anticipated that any activities would result ina temporary increase in risk to the environment or the community because the remedial alternatives donot involve extensive excavation, exposure of impacted material, or use of imported sources of potentialrisk. Nonetheless, each of the alternatives presents the potential for increased risk.

Alternative G-5 involves monitoring well installation and ground water sampling, which willpresent potential risk to remediation workers. Alternative G-2 would involve extraction well installation,ground water sampling, ground water extraction, and ground water storage above ground prior tooff-site removal. Each of these activities presents a potential for increased risk in the short-term, due toroutine O&M or potential system failure. Lastly, Alternatives G-3 and

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and G-4 present the highest potential for increased short-term risk. As with G-2 they involve wellinstallation and groundwater extraction. Additionally, these options involve on-site treatment whichpresents additional potential for risk.

6. Implementability considers the technical and administrative feasibility of implementingthe alternative such as relative availability of goods and services.

Technical and administrative implementability are both factored into this comparison. Alternative S-5, the GCL cap and Alternative S-2, the clay and soil cap are both technically andadministratively implementable. Alternatives S-3, the phytocap, has not been demonstrated in the stateof Nebraska.

An alternative cover design could be considered implementable if it meets the equivalentreduction and equivalent protection standards specified in Nebraska Title-132 and the ground waterprotection standards of Nebraska Title-118.

With regard to ground water remediation, technical implementability is more easily assessed,based on the required level and difficulty of remedial action. Alternative G-5, natural attenuation, whichonly includes monitoring is more easily implemented than Alternative G-2 which is more technicallycomplex. Alternatives G-3 and G-4 present the next levels of technical implementability, basedgenerally on the amount and difficulty of site activity required.

All ground water alternatives include the provision for ground water use restrictions throughinstitutional controls. The technical implementability of these actions are in review but since they arecommon to all ground water options the implementability does not effect the relative ranking ofalternatives.

7. Cost includes estimated capital and O&M costs as well as present worth cost. Presentworth cost is the total cost of an alternative over time in terms of today’s dollar value.Cost estimates are expected to be accurate within a range of +50 to -30 percent.

Table 6 summarizes the capital and O&M costs for all alternatives. The present value costrepresents the equivalent value in 1999 dollars of the corresponding remedy. The capital costs of thecapping options include design and construction of the landfill cap. The O&M costs for the capalternatives include periodic mowing, inspections, drainage maintenance, and routine cover maintenanceactivities for a 30-year duration.

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TABLE 6.SUMMARY OF COST ESTIMATES FOR REMEDIAL ALTERNATIVE

AlternativeNumber

Capital Cost Annual Operation andMaintenance

Total Present Worth

S-1 $0 $0 $0

S-2 $2,097,000 $19,000 $2,394,000

S-3 $1,430,000 $20,000 $1,741,000S-5 $1,784,000 $21,100 $2,109,300

G-1 $0 $0 $0

G-2 $147,000 $33,000 $654,000

G-3 $445,000 $38,000 $1,030,000

G-4 $231,000 $61,000 $1,173,000G-5 $108,0001 $32,000 $602,000

Project management and contingency costs are included in line item costsAll present worth costs assume %5 annual discount rateAssumes O&M Inspections for 30 years

The phytocap design is the least costly cover based on preliminary design assumptions.However, the design assumptions have not been formally accepted by the state and the cost estimatefor this alternative is subject to change pending resolution of design standards.

The GCL cap is more expensive than the phytocap design but less expensive than the clay andsoil cap alternative.

Natural attenuation will involve costs associated with monitoring well installation, extensivemonitoring, and data evaluation. The other three remediation systems all involve design, well and systeminstallation, remediation O&M, and ground water disposal or discharge expenses. The detailedelements, including all assumptions, of capital and O&M costs for each alternative are included in theFS and FS Addendum and included as Appendix A and Appendix B of this ROD.

8. State/Support Agency Acceptance consider whether the state agrees with U.S. EPA’sanalyses and recommendations of the RI/FS and the Proposed Plan.

The state of Nebraska has expressed its support for the selected remedy. The state does notbelieve the no action alternative provides adequate protection of human health and the environment.The state believes that the surface water controls and geosynthetic clay liner

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(GCL) cap remedy will provide effective source control, but has not eliminated consideration of analternative landfill cover remedy that is designed in accordance with the performance standards of Title132 and Title 118 and the applicable provisions of the EPA’s FS remedy selection criteria. The statealso believes that the ground water use restrictions and natural attenuation remedy will minimize thethreat of human exposure to the ground water contamination through the use of institutional controlswhile the effectiveness of natural attenuation is evaluated in restoring the aquifer to the MCLs in anacceptable time frame. If the ground water use restrictions and natural attenuation remedy is determinedto be ineffective in achieving the cleanup goals for the Site, the state believes the remedy decisionshould be reconsidered, and a contingency remedy implemented in accordance with an alternativetechnology specified in the FS Report or by modification or enhancement of the selected remedy.

9. Community Acceptance considers whether the local community agrees with U.S. EPA’sanalyses and preferred alternative. Comments received the Proposed Plan are animportant indicator community acceptance.

The EPA held a public comment period to allow the community to comment on the preferredalternative as set forth in the Proposed Plan and on the other alternatives considered. A number ofcomments were received from representatives of the PRPs who stated that the GCL landfill cover wastoo costly and over-designed for Site conditions. These representatives expressed a preference for thephytocap alternative, which is considered an alternative landfill cover design by state regulations. As aresult of these comments, EPA in consultation with NDEQ, will evaluate an alternative cap to determineif it will meet the requirements of Title 132, Title 118, and the other FS remedy selection criteria.

A number of comments were received in support of the monitored natural attenuation remedy.A few comments were received against the proposed institutional control measures but no commentswere received in opposition to the selected MNA ground water remedy.

The EPA considered all the public comments and has selected the GCL (or Alternative)landfill cap and MNA as the remedy. The monitoring will confirm whether or not the ground water canbe restored within a reasonable length of time under existing conditions. The EPA’s responses to thepublic comments are included in the Responsiveness Summary contained in the Administrative Record.

Table 7 summarizes the comparative analysis of the source control alternatives. Table 8summarizes the comparative analysis of the ground water remedy alternatives.

SELECTED REMEDY

The selected alternative for the remedial action to clean up the Site consist of:

• Surface water controls and GCL (or alternative) cap for soil and landfill contents.

• Ground water use restrictions and monitored natural attenuation for ground water.

23

24

25

These alternatives represent practical and cost-effective technologies that satisfy ARARs andhave the potential to achieve the remedial action objectives.

Surface Water Controls and GCL (or Alternative) Landfill Cap

Surface water controls and GCL (or alternative) landfill cap is selected as the remedy that

minimizes exposure to landfill contents and provides the most reduction in infiltration through the landfillto ground water. In response to public comment, EPA in consultation with NDEQ will evaluateadditional information on an alternative cap to determine if the alternative cap will meet the equivalentreduction and equivalent protection standards of Title 132, will meet the source control remedial actionrequirements of Title 118, and will satisfy the FS remedy selection criteria.

An alternative cap design may be implemented if it satisfies the requirements of Nebraska’sTitle 132 – Integrated Solid Waste Management Regulations, Chapter 3, 005.01B. This regulationrequires the alternative design to provide “equivalent reduction” in infiltration and “equivalentprotection” from wind and water erosion as traditional designs specified in 005.01A.

In addition, the substantive requirements of Title 118 – Ground Water Quality Standards andUse Classification, Chapter 10 and Appendix A are applicable at this Site. The HGWCS is a RAC-1occurrence and shall receive the most extensive remedial action measures. The preliminary cleanuplevels for the ground water are the MCLs. As such, source control remedial action will need to beperformed to minimize further infiltration of contaminants to the ground water at levels exceeding theMCLs.

The EPA selection of the final cover design will be based on a demonstrated ability to satisfythe state’s landfill cover performance standards as set forth in Title 132, ability to achieve Title 118groundwater standards, and to satisfy the EPA remedy selection criteria.

Post-closure inspection and maintenance would be conducted to maintain the integrity of the

final cover system. Surface water management, access control, and explosive gas monitoring will alsobe performed. Institutional controls for the landfill property will include a deed notice, property warningsigns, and a fence to restrict unauthorized access. The deed notice will consist of a permanent notationto the disposal area property to be recorded in the permanent records of the County Register of Deeds.This notation must include the following information: the existence of a solid waste disposal area; thetype, depth, and location of the waste; the existence of any monitoring systems; and any restrictions onthe use of the property to protect the integrity of the final cover and monitoring systems. The city will beresponsible for implementing these restrictions. There will be no land use restrictions imposed onoff-site properties other than the ground water use restrictions described below.

26

Ground Water Use Restrictions and Natural Attenuation Recommendation

Ground water use restrictions and monitored natural attenuation is selected as the ground waterremedy.

Monitored Natural Attenuation: EPA has determined that suitable biological activity and geochemicalconditions are present and that MNA has the potential to successfully address the entire body ofimpacted ground water with minimal Site disruption. This determination was based on the followingfindings:

• Prior sampling of landfill monitoring wells detected the presence of cis-1,2-dichloroethylene and vinyl chloride. These compounds are breakdown products oftrichlorethylene and recognized indicators of biodegradation processes;

• Extensive sampling of ground water at the nearby North Landfill Subsite hasdemonstrated that natural attenuation processes are occurring in the aquifer and aresuccessfully reducing the size of the contaminant plume down gradient from this subsite;

• The highest levels of contamination measured at the down-gradient Site boundary in1995-1996 were within EPA’s range of acceptable risk (i.e., the TCE level of 50 µg/1corresponds to an excess cancer risk of 1 x 10-5) but above the MCL. Contaminantlevels need only be reduced by an order of magnitude in order to achieve the MCLgoals or 1 x 10-6 risk levels; and

• The installation of a landfill cap will significantly reduce infiltration into the landfill andresult in a further reduction in migration of contaminants out of the landfill.

• MNA has the potential to achieve remedial action objectives and ARARs at a relativelylow cost.

The ultimate objective for the ground water portion of this remedial action is to restorecontaminated ground water in the aquifer to its beneficial uses. Based on information obtained duringthe remedial investigation and a careful analysis of all remedial alternatives, EPA and the state expectthat the selected remedy will achieve this objective in a reasonable time frame (i.e., < 20 years).

Monitored natural attenuation (Alternative G-5) will be used to restore the aquifer to beneficialuse. Additional ground water studies are planned to define the contaminated plume and to demonstratethat natural attenuation is occurring according to expectations. A monitoring program to be developedshall specify the location, frequency, and types of samples and measurements necessary to evaluatewhether the remedy is performing as expected and is capable of attaining remediation objectives.Although the estimated time for natural processes to attain remediation objectives may be longer thanthat required for alternatives using pump and treat, planned studies will ensure that natural attenuationwill achieve cleanup in a reasonable time (i.e., < 20 years) while ensuring that there are no unacceptableexposures to contaminated ground water within this period.

27

Planned studies will be implemented to evaluate two separate lines of evidence (trends ofdeclining COCs and predictive modeling) to indicate that monitored natural attenuation will besuccessful in attaining remediation objectives for Site ground water. Actual performance of the naturalattenuation remedy will be carefully monitored in accordance with the ROD. If monitoring data indicatethat contaminant levels do not continue to decline, as estimated in the modeling predictions, the EPAand the state will reconsider the remedy decision. One or more of the following observations could leadto re-consideration of the remedy if confirmed by three or more rounds of sampling:

• Increase in levels of parent contaminants indicating that other sources may be present.

• Concentration levels of contaminants and/or break-down products differ significantlyfrom modeling predictions.

• The plume for TCE, and its breakdown products of cis-1,2-DCE and VC, increasessignificantly in areal or vertical extent and/or volume from that predicted by modelingestimates.

To satisfy the ARARs, ground water use restrictions are required both on-site and off-site forareas where levels of contamination exceed MCLs. A proposed institutional control ordinance willprevent installation of new domestic wells in the institutional control area, which includes the landfillproperty. Other types of water wells, such as irrigation and industrial wells, may be installed in theinstitutional control area but only after obtaining a permit. Existing drinking wells in the impacted areawill be assessed and may be removed from use, if necessary. Restricting access to impacted groundwater is common to all the ground water alternatives. By combining ground water use restrictions withnatural attenuation, Alternative G-5 ensures protection of receptors by eliminating the potential forexposure while providing, or verifying the occurrence of, remediation in both the most heavily impactedarea below the landfill and in the less impacted areas off Site.

Natural attenuation was selected over extraction and chemical/hydraulic containmentalternatives for several reasons. First, Alternative G-5 is consistent with alternatives being considered toaddress the regional ground water contamination issues. Second, it does not involve any intrusivedisturbances to the Site because monitoring alone will be sufficient to implement the remedy. Third, itcan address the entire body of impacted water, while the containment alternatives only activelyremediate ground water as it passes below the downgradient property boundary. Lastly, as the onlyremedy that truly destroys the constituent, natural attenuation provides the greatest potential forlong-term cost-effectiveness of all the options.

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Contingency Remedy: The EPA recommends that remedies employing monitored natural attenuationinclude contingency measures that would be capable of achieving remediation objectives. Selection of acontingency remedy in this ROD is appropriate because the monitored natural attenuation remedy hasbeen selected based on limited analysis rather than documented trends of decreasing contaminantconcentration. If further studies indicate that any of the above-noted conditions are occurring, EPA inconsultation with NDEQ, may determine that natural attenuation is not performing according toexpectations and that alternative contingency remedies should be considered and/or implemented.Alternative contingency remedies which have been identified for this Site include the use of enhancedbiodegradation technologies or implementation of a “pump and treat” alternative such as AlternativeG-2, ground water use restrictions, hydraulic containment using vertical extraction wells and dischargeto an off-site facility.

Ground Water Use Restriction: Ground water use restrictions will be implemented through the use ofinstitutional controls. Access restrictions may range from ground water use restrictions at the SouthLandfill property that will prohibit the extraction of ground water for potable use to an institutionalcontrol area.

Ground water monitoring is proposed in combination with institutional controls. A sampling andanalysis program will be implemented to monitor the condition of the aquifer beneath and adjacent to asite. Periodic monitoring will be performed to monitor ground water characteristics and flow patterns.In the event that additional sampling results in the detection of contamination in a drinking water supplyabove MCL levels, the affected residents will be offered an alternative water supply until such time asthe ground water is remediated.

The estimated cost of the selected remedy is:

Source Control Remedy1 Ground Water Remedy Total Project

Capital Cost $1,784,300 $108,000 $1,892,300Annual O&M $21,100/year $32,000/year $53,100/yearTotal Present Worth2 $2,109,400 $602,000 $2,711,400

1 - Geosynthetic Clay Liner Cap2 - The estimated costs are based on an assumed discount rate of 5% over 30 years

STATUTORY DETERMINATIONS

Under CERCLA §121 and the NCP, the lead agency must select remedies that are protectiveof human health and the environment, comply with applicable or relevant and appropriate requirements(unless a statutory waiver is justified), are cost-effective, and utilize permanent solutions and alternativetreatment technologies or resource recovery technologies to the maximum extent practicable. Inaddition, CERCLA includes a preference for remedies that employ treatment that permanently andsignificantly reduces the volume, toxicity, or mobility of

29

hazardous wastes as a principal element and a bias against off-site disposal of untreated wastes. Thefollowing sections discuss how the selected remedy meets these statutory requirements.

Protection of Human Health and the Environment: The selected remedy will protect human health andthe environment by controlling the migration of contaminants from the landfill source and by monitoringthe degradation and reduction of groundwater contaminant levels through natural attenuation processes.Capping the contaminated soil will eliminate the threat of exposure to the most mobile chemical ofpotential concern via direct contact with or ingestion of contaminated soil. The selected remedy will alsominimize the potential for leachate generation and recontamination of ground water. The current cancerrisks associated with these exposure pathways exceeds 1 x 10-6. The selected remedy will reduce thecancer risks from exposure to the 1 x 10-6 risk level. There are no short-term threats associated withthe selected remedy that cannot be readily controlled. In addition, no adverse cross-media impacts areexpected from the selected remedy.

Compliance with Applicable or Relevant and Appropriate Requirements: Section 121(d)(2) ofCERCLA, 42 U.S.C. § 9621(d)(2), requires that cleanup actions conducted under CERCLA achievea degree or level of cleanup which, at a minimum, attains any standard, requirement, criteria or limitationunder any federal environmental law ... or any promulgated standard, requirement, criteria or limitationunder a state environmental or facility siting law that is more stringent than any federal standard ...[which] is legally applicable to the hazardous substance or pollutant or contaminant concerned or isrelevant and appropriate under the circumstances of the release or threatened release of such hazardoussubstance or pollutant or contaminant... The identified standards, requirements, criteria or limitationsthus adopted from other environmental laws, which govern on-site cleanup activities at this Site, arereferred to as “applicable or relevant and appropriate requirements” or ARARs.

For on-site cleanup activities under Section 121(e)(1) of CERCLA, EPA is not required toobtain any federal, state, or local permits for actions conducted on site, complying only with thesubstantive (non-administrative) requirements of the identified federal and state laws. On the otherhand, for cleanup activities that will occur off-site, both the substantive as well as the administrativerequirements of such laws will apply to cleanup activities. This section identifies the ARARs which willapply to the on-site cleanup activities.

The selected remedy will comply with the following ARARs, as well as additional ARARsidentified in the FS:

Safe Drinking Water Act of 1986, as amended (SDWA) (42 U.S.C. 300 et seq): Primary DrinkingWater Standards are established in 40 CFR Part 141. The SDWA MCLs are health-based standardsfor chemicals that may be found in public water supplies. The NCP requires consideration of MCLs,where they exist, as relevant and appropriate requirements for ground water cleanups when the aquiferis a current or potential source of drinking water. MCLs for the chemicals of concern are relevant andappropriate for establishing cleanup standards to be met upon completion of the remedy.

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Nebraska Ground Water Quality Standards and Use Classification: Title 118, Chapter 4: Thesubstantive requirements of NDEQ’s Title 118 % Ground Water Quality Standards and UseClassification, Chapter 10 and Appendix A are applicable at this site because hazardous substancesfrom wastes disposed at the South Landfill have contaminated the ground water supply. In accordancewith Title 118, Chapter 10, 001, the Ground Water Remedial Action Protocol found in Appendix Ashall apply when a point source pollution event has caused or will cause, in the NDEQ’s judgment,ground water pollution. Step 8 of the Protocol establishes a method for determining preliminary cleanuplevels for the different classifications of protected ground water. The ground water in the vicinity of theSite has been designated as a Class GA Ground Water Supply by the state of Nebraska. A Class GAGround Water is a ground water supply which is currently being used as a public drinking water supplyor is proposed to be used as a public drinking water supply. Contamination detected down gradientfrom the Site has caused the state to designate the Site as a RAC-1 incident requiring “the mostextensive remedial action measures” to clean up the ground water to drinking water quality and suitablefor all other beneficial uses. As set forth in the Protocol, the cleanup level governing a RAC-1occurrence is the achievement of MCLs or, if there is no established MCL, 1 x 10-6 risk level.

Resource Conservation and Recovery Act (RCRA) Requirements for Landfill Closure and PostClosure: The RCRA requirements for final cover systems at municipal solid waste landfills can befound at 40 C.F.R. Part 258. Although these regulations are not applicable to this Site since wasteswere not received after October 9, 1991, EPA has determined that they are relevant and appropriateat this Site in order to provide the necessary source control to minimize further infiltration ofcontaminants to the ground water at levels exceeding the MCLs or, if there is no established MCL, 1 x10-6 risk level. These regulations require a final cover system designed and constructed to: (1) have apermeability less than or equal to the permeability of any bottom liner system or natural subsoilspresent, or a permeability no greater than 1 x 10-5 cm/sec, whichever is less, and (2) minimize infiltrationthrough the closed municipal solid waste landfill by the use of an infiltration layer that contains aminimum 18-inches of earthen material, and (3) minimize erosion of the final cover by the use of anerosion layer that contains a minimum 6-inches of earthen material that is capable of sustaining nativeplant growth. An alternative final cover design may be approved by the State that includes: (1) aninfiltration layer that achieves an equivalent reduction in infiltration as the infiltration layer specifiedabove, and (2) an erosion layer that provides equivalent protection from wind and water erosion as theerosion layer specified above. (See discussion below of Nebraska Title 132 % Integrated Solid WasteManagement Regulations, Chapter 3, 005 and 006) . In addition, 40 C.F.R. Part 258 requirespost-closure care requirements.

The EPA has information that hazardous wastes were disposed at the Site after November 18, 1980.Therefore, the substantive landfill closure and post-closure requirements of RCRA Subtitle C found at40 C.F.R. 265.310 in effect at the time the South Landfill ceased its operations are applicable. TheEPA believes that the selected remedy complies with the applicable requirements set forth in Subtitle C.

31

Nebraska Integrated Solid Waste Management Regulations Title 132: The closure and post-closurerequirements of Nebraska Title 132 % Integrated Solid Waste Management Regulations, Chapter 3,005 and 006 are not applicable as waste was received at the Site prior to the effective dates of theserequirements (October. 1, 1993). However, the substantive Nebraska Title 132 closure andpost-closure requirements are relevant and appropriate at this Site in order to provide the necessarysource control to minimize further infiltration of contaminants to the ground water at levels exceeding theMCLs or, if there is no established MCL, 1 x 10-6 risk level.

Title 132, Chapter 3, 005.01A requires final cover systems to consist of an 18 inch infiltrationlayer that has a permeability less than or equal to the permeability of the bottom liner system or naturalsubsoil present, or a permeability no greater than 1 X 10-5 cm/sec, measured at the site, whichever isless; and an overlying 18 inch erosion layer capable of sustaining vegetative cover. Title 132, Chapter3, 005.01B allows an alternate final cover system design that includes an infiltration layer that achievesan equivalent reduction in infiltration as the infiltration layer specified in 005.01A above and an erosionlayer that provides equivalent protection from wind and water erosion as the erosion layer specified in005.01A above.

Title 132, Chapter 3, 006 requires 30 years of post-closure care that includes annual inspectionand maintenance of the cover to ensure integrity and maintenance, run-off control structures and accesscontrol structures, maintenance and semi-annual sampling of any existing ground water monitoring wells,and maintenance and quarterly sampling of any landfill gas monitoring systems. A permanent notation onthe deed to the disposal area property must be recorded in the permanent records of the CountyRegister of Deeds. This notation must include the following information: the existence of a solid wastedisposal area; the type depth and location of the waste; the existence of any monitoring systems; andany restrictions on the use of the property to protect the integrity of the final cover and monitoringsystems.

Other Criteria, Advisories, or Guidance To Be Considered (TBCs) for This Remedial Action: Inimplementing the selected remedy, the EPA and the state have agreed to consider a number ofnon-binding criteria that are TBCs. These include the guidance on designing RCRA caps, Draft RCRA,Guidance Document, Landfill Design, Liner Systems, and Final Cover, issued June 1982. Theguidance on designing RCRA caps includes specifications to be followed in constructing andmaintaining a RCRA cap. Solid Waste Disposal Facility Criteria-A Technical Manual, November,1993.

Cost-Effectiveness: In the lead agency’s judgment, the selected remedy is cost-effective and representsa reasonable value for the money to be spent. In making this determination, the following definition wasused: “A remedy shall be cost-effective if its costs are proportional to its overall effectiveness.”[NCP§300.430(f)(1)(ii)(D)]. This was accomplished by evaluating the “overall effectiveness” of thosealternatives that satisfied the threshold criteria (i.e., were both protective of human health and theenvironment and ARAR-compliant). Overall effectiveness was evaluated by assessing three of the fivebalancing criteria in combination (long-term effectiveness and permanence; reduction in toxicity,mobility, and volume through treatment;

32

and short-term effectiveness). Overall effectiveness was then compared to costs to determinecost-effectiveness. The relationship of the overall effectiveness of this remedial alternative wasdetermined to be proportional to its costs and hence this alternative represents a reasonable value forthe money to be spent. The estimated present worth cost of the selected remedy is $2,711,400. TheEPA believes that the selected remedy’s additional cost for reducing infiltration provides a significantincrease in protection of human health and the environment and is cost-effective. The EPA also believesthat the selected remedy’s combination of source control and monitored natural attenuation will providean overall level of protection comparable to the ground water pump and treat alternatives at asignificantly lower cost.

Utilization of Permanent Solutions and Alternative Treatment Technologies (or Resource RecoveryTechnologies) to the Maximum Extent Practicable: The EPA has determined that the selected remedyrepresents the maximum extent to which permanent solutions and treatment technologies can be utilizedin a practicable manner at the site. Of those alternatives that are protective of human health and theenvironment and comply with ARARs, EPA has determined that the selected remedy provides the bestbalance of trade-offs in terms of the five balancing criteria, while also considering the statutorypreference for treatment as a principal element and bias against off-site treatment and disposal andconsidering state and community acceptance. Although the selected remedy does not utilize engineeredtreatment technologies, capping of the landfill will nearly eliminate migration of contaminants from thelandfill to underlying ground water, which will reduce contaminant concentrations in the ground water.The selected remedy treats the source materials at the Site and achieves significant reductions incontaminant concentrations in ground water.

Preference for Treatment as a Principal Element: The preamble to the NCP identifies municipal landfillsas a type of site where treatment of the waste may be impracticable because of the size andheterogeneity of the contents. Because treatment usually is impractical, EPA has developed“presumptive remedy” guidance which considers containment to be the appropriate response action forthe source areas of municipal landfill sites. Based on the size and location of the landfill, EPA concludedthat it was impractical to excavate and treat the chemicals of concern in a cost-effective manner. Thusthe remedy does not satisfy the statutory preference for treatment as a principal element of the remedy.

Five-Year Review Requirements: Because this remedy will result in hazardous substances, pollutants,or contaminants remaining on Site above levels that allow for unlimited use and unrestricted exposure, astatutory review will be conducted within five years after initiation of the remedial action to ensure thatthe remedy is, or will be, protective of human health and the environment.

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DOCUMENTATION OF SIGNIFICANT CHANGES FROM PREFERREDALTERNATIVE OF PROPOSED PLAN

The Proposed Plan, released for public comment on June 30, 2000, presented the preferredalternative as;

• Surface Water Controls and GCL Cap for Soil and Landfill Contents, and

• Ground Water Use Restrictions and Natural Attenuation for Ground Water Remediation.

The EPA reviewed all written and verbal comments submitted during the public commentperiod and has determined that a significant change in the remedy is warranted. The EPA believes thesignificant change as outlined in this ROD could have been reasonably anticipated based, uponinformation originally presented in the Proposed Plan and the RI/FS Reports.

The cost estimate for Alternative S-5 surface water controls and GCL cap for soil and landfillcontents was revised to reflect changes in cost assumptions to be consistent with the estimates for othersource control (landfill cap) alternatives presented in the FS. The revised cost estimate resulted in anincrease in the total present worth for Alternative S-5 from $1,665,000 to $2,109,400.

The source control remedy has been modified to allow for the implementation of an alternativelandfill cap design which meets the performance standards specified in Nebraska Title 132 - IntegratedSolid Waste Regulations, Chapter 3, 005.01B.

It has been determined that suitable biological activity and geochemical conditions are presentand that natural attenuation has the potential to successfully address the entire body of impacted groundwater with minimal Site disruption. Based on this information, the selected remedy will be implementedas a final remedy and not as an interim remedy as indicated in the Proposed Plan.

APPENDIX A

Cost Estimate Calculations

South Landfill Subsite Feasibility Study April 14, 2000

9/19/00 draft

Page 1

Cost Estimate Calculations. South Landfill Feasibility Study, Hastings Nebraska

Remediation Alternative: S-1No Action

Alternative Components: Capital Cost ($) Annual Cost ($/yr)

Total $ - $ -

Remediation Alternative: S-2

Surface Water Control and Clay and Soil Cap


Regrade Areas for Drainage and Site Preparation $ 378,000

Install Cap $ 1,719,113O&M $ 19,305

Total $ 2,097,113 $ 19,305

Present Worth $ 2,393,878

Remedaition Alternative: S-3

Surface Water Controls and Phytocap


Regrade Areas for Drainage and Site Preparation $ 1,348,299

Site Preparation $ 6,750

Tree Installation and Fertilization $ 74,723O&M $ 20,250

Total $ 1,429,772 $ 20,250


Remediation Alternative: G-1

No Action


Total $ - $ -


Groundwater Use Restrictions, HydraulicContainment Using Vertical Extraction Wells, and

Groundwater Reuse


Groundwater Use Restrictions $ 33,750

Install Wells $ 60,750

Groundwater Extraction/Reuse $ 52,650

Monitoring $ 20,790

O&M $ 12,150Total $ 147,150 $ 32,940

Present Worth $ 653,519


Groundwater Use Restrictions and Chemical

Containment Using Sparge Curtain




Page 2

Cost Estimate Calculations. South Landfill Feasibility Study, Hastings Nebraska

Air Sparging, Vapor Extraction $ 40,500

Vapor Treatment $ 12,825

Monitoring $ 20,790

O&M $ 17,280

Total $ 444,825 $ 38,070



Groundwater Use Restrictions, HydraulicContainment Using Vertical Extraction Wells,

Treatment by Carbon Adsorption, and Discharge to

On-site Stream




Water Collection/ Treatment/ Discharge $ 136,350

Monitoring $ 20,790

O&M $ 40,500Total $ 230,850 $ 61,290



Groundwater Use Restrictions and Natural

Attenuation



Install Wells $ 54,000Biogeochemical Evaluation $ 20,250

Monitoring $ 32,130

Total $ 108,000 $ 32,130

Present Worth $ 601,917

Note: Project management and contingency costs are included in line item totals.All present value costs assume 5% annual discount rate.

South Landfill SubsiteHastings, NebraskaFeasibility Study Cost Calculations

Page 3

Remediation Alternative: S-1 No Action

Alternative Components: Ç None

Project Total $


Page 4

Remediation Alternative: S-2 Surface Water Control and Clay and Soil Cap

Alternative Components: Ç Regrade Areas for Drainage and Site PreparationÇ Install CapÇ O&MÇ Project Management

Regrade Areas for Drainage and Site Preparation Quantity Unit Unit Cost Total

Design and construction ofcap bedding materialGrading Design 1 LS $ 10,000 $ 10,000

Common Borrowfor clay bedding material

27,000 CY $4.00 $ 108,000

Fill placement,compaction

27,000 CY $6.00 $ 162,000


Install Cap Quantity Unit Unit Cost Total

Construction of clay and soilcover system

Clay MaterialTransport, placement, compaction (18")

67,000 CY $13.00 $ 871,000

Frost Protection Transport,placement

67,000 CY $4.00 $ 268,000

TopsoilTransport, Placement

22,000 CY $5.50 $ 121,000

Vegetative Layerseeding fertilizer

134,167 SY $0.10 $ 13,417

Install Cap $ 1,273,417

O&M Quantity Unit Unit Cost Total

O&M costs include 6 inspections per yearroutine mowing, and needed improvementsSite Inspections ($/yr)assume 4/yr

6 each $ 750 $ 4,500


Page 5

Remediation Alternative: S-2 Surface Water Control and Clay and Soil Cap

Mowing ($/yr)assume 8 times peryear

6 each $ 800 $ 4,800

Repairs as needed($/yr) estimated annualcost

1 LS $ 5,000 $ 5,000

O&M $/year $ 14,300

ContingenciesContingencies include costs not included in estimateand costs incurred due to unforeseen circumstancesContingencies 20% of cost

Project ManagementReporting, contracting, contractorcoordination, project management,permittingProject Management

15% of cost

Project Total - Capital Costs $ 2,097,113

Project Total - Annual Costs 30 yr period $ 19,305

Project Total - Present Worth Cost (1999) $ 2,393,878

Assumes O&M and Inspections for 30 years Annual discount rate: 5%


Page 6

Remediation Alternative: S-3 Surface Water Controls and Phytocap

Alternative Components: Ç Regrade Areas for Drainage and Site PreparationÇ Site PreparationÇ Tree Installation and FertilizationÇ O&MÇ Project Management

Regrade Areas for Drainage and Site Preparation Quantity Unit Unit Cost Total

Design and construction ofcap bedding materialGrading Design 1 LS $ 10,000 $ 10,000

Common Borrow forgrading

27,000 CY $4.00 $ 108,000

Fill placement, compaction 27,000 CY $ 6.00 $ 162,000

Erosion Layer (topsoil)3 feetfor root development/ erosion protection

130,680 CY $5.50 $ 718,740


Site Preparation Quantity Unit Unit Cost Total

includes site mobilization and sitepreparation

Mobilization and site prep 1 LS $ 5,000 $ 5,000

Site Preparation $ 5,000

Tree Installation and Fertilization Quantity Unit Unit Cost Total

Vegetation supply, planting, monitoring,and first year of maintenanceVegetation supply light bush, fewpoplar trees, grasses raw materialsonly

27 acre $ 1,400 $ 37,800

Installation of vegetationplanting of vegetation

27 acre $ 200 $ 5,400

Fertilization and seeding 27 acre $ 450 $ 12,150


Page 7

Remediation Alternative: S-3 Surface Water Controls and Phytocap

Tree Installation and Fertilization $ 55,350


O&M costs include 6 inspections per yearroutine mowing, and needed improvements

Maintenance as needed ($/yr)estimated annual cost

1 LS $ 10,000 $ 10,000

Phyto maintenance visits includessampling, reevaluation

1 LS $ 5,000 $ 5,000

O&M $/year $ 15,000

ContingenciesContingencies include costs not includedin estimate and costs incurred due tounforeseen circumstancesContingencies 20% of cost

Project ManagementReporting, contracting, contractor coordination, projectmanagement, permittingProject Management 15% of cost

Project Total - Capital Costs $ 1,429,772

Project Total - Annual Cost 30 yr period $ 20,250


Assumes O&M and Monitoring for 30 years Annual discount rate: 5%


Page 8

Remediation Alternative: G-1 No Action

Alternative Components: Ç None

Project Total $ -


Page 9

Remediation Alternative: G-2 Groundwater Use Restrictions, Hydraulic ContainmentUsing Vertical Extraction Wells, and Groundwater Reuse

Alternative Components: Ç Groundwater Use RestrictionsÇ Install WellsÇ Groundwater Extraction/ReuseÇ MonitoringÇ O&MÇ Project Management

Groundwater Use Restrictions Quantity Unit Unit Cost Total

Legal activities required to placeGroundwater UseRestriction Administrative Costs

1 LS $ 25,000 $ 25,000


Install Wells Quantity Unit Unit Cost Total

Drilling and iIstallation/Development of 3 extractionwells6" wells to 140 feetDrilling /material cost

3 well $ 10,000 $ 30,000

Drilling oversight 1 LS $ 15,000 $ 15,000


Groundwater Extraction/Reuse Quantity Unit Unit Cost Total

Includes costs for network piping

Force main, trenching, valve assembly1300 feet of pipe/trench

1,300 LF $ 30 $ 39,000

Groundwater Extraction/Reuse $ 39,000

Monitoring Quantity Unit Unit Cost Total

Per Year Cost for GW monitoring


Page 10

Remediation Alternative: G-2 Groundwater Use Restrictions, Hydraulic ContainmentUsing Vertical Extraction Wells, and Groundwater Reuse

Semi-annual sampling, seven wells, VOCsonly Labor, Sampling ($/yr) 1 LS $ 5,000 $ 5,000

Laboratory Analysis ($/yr)8 water samples (VOCs)/event

16 sample $ 150 $ 2,400

Reporting ($/yr)1 report per yearlabor, report production

1 report $ 8,000 $ 8,000

Monitoring $/year $ 15,400


Per year fees for system operation,Primarily site visits and powerO&M visit/ repairs ($/yr)6 inspections/yearminor maintenance

6 insp $ 1,000 $ 6,000

Power Costs ($/yr) 12 month $ 250 $ 3,000

O&M $/year $ 9,000

ContingenciesContingencies include costs not included in estimateand costs incurred due to unforeseen circumstancesContingencies 20% of cost

Project Management

Reporting, contracting, contractor coordination, project management, permitting

Project Management 15% of cost

Project Total - Capital Costs $ 147,150


Project Total - Present Worth Cost (1999) $ 653,519



Page 11

Remediation Alternative: G-3 Groundwater Use Restrictions ad Chemical ContainmentUsing Sparge Curtain

Alternative Components: Ç Groundwater Use RestrictionsÇ Install WellsÇ Air Sparging, Vapor ExtractionÇ Vapor TreatmentÇ MonitoringÇ O&MÇ Project Management


Legal activities required toplace Groundwater UseRestriction AdministrativeCosts

1LS $ 25,000 $ 25,000



Drilling and Installation/Development of 48 spargewells4" wells to 140 feetDrilling/material costdual sparge and SVE wells

48 well $ 5,000 $ 240,000



Air Sparging, Vapor Extraction Quantity Unit Unit Cost Total

Includes costs for network pipingand aboveground system installationSVE Network Piping, trenching, valve assemblyAlso sparging air distributionIncludes blowers and compressors

1 LS $ 30,000 $ 30,000

Air Sparging, Vapor Extraction $ 30,000

Vapor Treatment Quantity Unit Unit Cost Total

Includes costs for carbon vesselspermitting efforts


Page 12

Remediation Alternative: G-3 Groundwater Use Restrictions and Chemical ContainmentUsing Sparge Curtain

Carbon vessel installationincludes plumbing system to vessels

1 LS $ 5,000 $ 5,000

Treatment Compound 1 LS $ 2,000 $ 2,000

Treatment Unit Permitting 1 LS $ 2,500 $ 2,500

Vapor Treatment $ 9,500


Per Year Cost for GW monitoringSemi-annual sampling, seven wells, VOCs onlyLabor, Sampling ($/yr) 1 LS $ 5,000 $ 5,000

Laboratory Analysis ($/yr)8 water samples (VOCS)/event

16 sample $ 150 $ 2,400


1 report $ 8,000 $ 8,000



Per year fees for system operation,Primarily site visits and carbonO&M visit/ repairs ($/yr)6 inspections/yearminor maintenance

6 insp $ 1,000 $ 6,000


Vapor sampling ($/yr)12 samples per year, to meetanticipated permit requirements

12 month $ 150 $ 1,800

Carbon Costs ($/yr) 1 yr $ 2,000 $ 2,000


Page 13

Remediation Alternative: G-3 Groundwater Use Restrictions and Chemical ContainmentUsing Sparge Curtain

O&M $/year $ 12,800

ContingenciesContingencies include costs not included in estimateand costs incurred due to unforeseen circumstancesContingencies

20% of cost

Project ManagementReporting, contracting, contractor coordination, project management,permittingProject Management 15% of cost






Page 14

Remediation Alternative: G-4 Groundwater Use Restrictions, Hydraulic ContainmentUsing Sparge Curtain

Alternative Components: Ç Groundwater Use RestrictionsÇ Install WellsÇ Water Collection/ Treatment/ DischargeÇ MonitoringÇ O&MÇ Project Management


Legal activities required to placeGroundwater Use Restriction Administrative Costs 1 LS $ 25,000 $ 25,000



Drilling and Installation/Development of 3 extractionwells6" wells to 140 feetDrilling/material cost

3 well $ 10,000 $ 30,000



Water Collection/ Treatment/ Discharge Quantity Unit Unit Cost Total

Includes costs for network piping andaboveground storage installationForce main, trenching, valve assembly1300 feet of pipe/trench

1,300 LF $ 30 $ 39,000

Filtration 1 LS $ 15,000 $ 15,000

Equalization Tank 1 LS $ 10,000 $ 10,000


Page 15

Remediation Alternative: G-4Groundwater Use Restrictions , Hydraulic Containment

Using Vertical Extraction Wells, Treatment by CarbonAdsorption, and Discharge to On-site Stream

Treatment Compound 1 LS $ 2,000 $ 2,000

Carbon Treatment Unit Assembly2 vessels

1 LS $ 30,000 $ 30,000

NPDES Discharge PermitConsultant fees

1 LS $ 5,000 $ 5,000

Water Collection/ Treatment/ Discharge $ 101,000


Per year Cost for GW monitoringSemi-annual sampling, seven wells, VOCsonly Labor, Sampling ($/yr) 1 LS $ 5,000 $ 5,000

Laboratory Analysis ($/yr)8 water samples (VOCs)/event

16 sample $ 150 $ 2,400


1 report $ 8,000 $ 8,000



Per year fees for system operation,Primarily site visits and powerO&M visit/ repairs ($/yr)6 inspections/yearminor maintenance

6 insp $ 1,000 $ 6,000



Page 16

Remediation Alternative: G-4Groundwater Use Restrictions , Hydraulic Containment

Using Vertical Extraction Wells, Treatment by CarbonAdsorption, and Discharge to On-site Stream

Discharge sampling ($/yr)12 samples per year, to meetanticipated NPDES permitrequirements

12 month $ 500 $ 6,000

Carbon costs ($/yr) 1 year $ 15,000 $ 15,000

O&M $/year $ 30,000


20% of costs

Project Management

Reporting, contracting, contractor coordination, project management,permittingProject Management 15% of cost




Assumes O&M and Monitoring for 30 years Annual discounts rate: 5%


Page 17

Remediation Alternative: G-5 Groundwater Use Restrictions and Natural Attenuation

Alternative Components: Ç Groundwater Use RestrictionsÇ Install WellsÇ Biogeochemical EvaluationÇ MonitoringÇ Project Management


Legal activities required toplace Groundwater UseRestrictionAdministrative Costs

1 LS $ 25,000 $ 25,000



Drilling and Installation/Development of 5 monitoringwells6" wells to 140 feetDrilling/material cost

5 well $ 5,000 $ 25,000



Biogeochemical Evaluation Quantity Unit Unit Cost Total

Data Management and EvaluationAssessment of Natural AttenuationSampling and Evaluation 1 LS $ 10,000 $ 10,000

ReportingPresent evaluation results report production

1 report $ 5,000 $ 5,000

Biogeochemical Evaluation $ 15,000



Page 18

Remediation Alternative: G-5 Groundwater Use Restrictions and Natural Attenuation

Per Year Cost for GW monitoringSemi-annual sampling, twelve wells, multipleparametersLabor, Sampling ($/yr)

1 LS $ 8,000 $ 8,000

Laboratory Analysis ($/yr)13 water samples/event

26 sample $ 300 $ 7,800

Reporting ($/yr)1 report per yearevaluation, report production

1 report $ 8,000 $ 8,000



20% of cost

Project ManagementReporting, contracting, contractor coordination, project management,permittingProject Management

15% of cost


Project Total - Annual Cost 30 year period $ 32,130

Project Total - Present Worth Cost (1999) $ 601,917


9/19/00 draft

APPENDIX B

Cost Estimate Calculations

South Landfill Subsite Feasibility Study AddendumJune 2000

Alternative S-5 Surface Water Controls and GCL Cap1

Quantity Unit Unit Cost Total

Regrade Areas for Drainage and Site Preparation

Grading Design 1 LS $10,000 $10,000

Common Borrow 27,000 CY $4.00 $108,000

Fill Placement Compaction 27,000 CY $6.00 $162,000

Regrade Total $280,000

Install Cap

Scarify and Recompact Existing soils 1,176,120 SF $3/1000 SF $3,528

*Materials and Placement of GCL 1,176,120 SF $0.40 $470,448

Erosion Layer 65,340 CY $9.50 $620,730

Vegetation 27 AC $726/AC $19,602

Install Cap Total 1,114,308

Contingencies 20%* $222,862

Project Management 15%* $167,146

Total Cap Construction Cost $1,784,316

O&M

Site inspections 4 each $750 $3,000

Mowing 4 each $500 $2,000

Repairs @ 5% of cap area; 1 ft deep/yr 2250 CY $5.50/CY $12,375

Seeding 1.35 AC $720/AC $972

O&M engineering & contingencies @ 35% $2,800

Total O&M costs/annual $21,147

Annual discount rate @5% for 30 years = 15.372 $325,072

Total Present Worth Costs (1999) $2,109,338

**Using 1’ common borrow material 43,560 CY $4.00 $174,240

Add 35% for engineering and contingencies $60,984

Additional cost using 1’ borrow Material $235,224

Total Cap Construction Cost $560,296

Total Present Worth Costs (1999) $2,669,684*Materials and placement of GCL is based on actual landfill costs of in NE**Assumes off-sitecommon borrow soils1 - Cost Estimate Revised 9/14/00

1 9/20/00 revision

RESPONSIVENESS SUMMARY

South Landfill SubsiteHastings Groundwater Contamination Site

INTRODUCTION

This responsiveness summary has been prepared in accordance with the ComprehensiveEnvironmental Response and Liability Act (CERCLA), as amended by the Superfund Amendments andReauthorization Act (SARA), and the National Contingency Plan (NCP) 40 CFR §300.430(f). Thisdocument provides the United States Environmental Protection Agency’s (EPA) response to all significantcomments received on the Proposed Plan from the public during the 60-day public comment period.

On June 30, 2000, the EPA released the Proposed Plan and Administrative Record File whichcontains the pertinent documents for the site. The Proposed Plan discussed the EPA’s proposed actionsto address contaminated soil and contaminated groundwater emanating from the site. The public commentperiod began on June 30, 2000. The EPA held a public meeting on July 20, 2000, at the Hastings PublicLibrary to present the Proposed Plan and provide the public an opportunity to comment. A copy of thetranscript from the public meeting is included in the Administrative Record File.

In response to a request received at the public meeting, the public comment period was extendedfor an additional 30-day period and ended on August 30, 2000.

COMMENTS RECEIVED DURING THE PUBLIC MEETING

Landfill Fill Material

Comments were made that certain statements in the Feasibility Study (FS) and FS Addendumregarding the landfill description, particularly the fill material, were inaccurate.

Revised language has been incorporated into the Record of Decision.

Cost Estimates

Comments were made that the cost estimate for the Geosynthetic Clay Liner (GLC) cover wereunderestimated because: 1.) the area to be capped was underestimated; and 2.) annual operation andmaintenance costs were underestimated.

The Feasibility Study submitted by the potential responsible party (PRP) group stated thatthe size of the landfill property was 58 acres and estimated that the size of the fill area to be 27acres. The landfill cover cost estimates are based on the assumption that 27 acres will be capped.

2

assumes the same 27-acre size cover area. A final decision on how much area will be capped willbe determined during the design phase of the project.

The Record of Decision includes a revised cost estimate for the GCL cap. Selection of thefinal cover design will be based on: 1) demonstrated ability to satisfy the state’s landfill coverperformance standards as set forth in Nebraska regulations, Title 118, Groundwater QualitySolid Standards and Title 132, Integrated Solid Waste Management Regulations and 2.)evaluation against EPA’s (nine) remedy selection criteria.

Comments were made that the cost for the Phytocap alternative may be over estimatedbecause it was based on a soil depth of three feet which may not be necessary to be effective.

The Nebraska Department of Environmental Quality (NDEQ) does not currently havedesign criteria for Alternative Cover Systems. The recommendation for a 36-inch soil cover isbased on EPA’s draft guidance for alternative landfill covers which recommends a calculatedsoil thickness using a factor of safety of 1.5 to 2.0 or a minimum of three feet.

In addition, this recommendation is consistent with the Alternative Cover AssessmentProgram test plot design at the Douglas County Recycling and Disposal Facility near Omaha,Nebraska which includes, in part, a 36-inch soil cover layer.

Phytocap, an Alternative Landfill Cover

A number of comments were made in support of the Phytocap Landfill Cover Alternative. ThePhytocap was promoted as an effective, but costly alternative to traditional landfill cover designs.

The EPA and the state will provide an opportunity for the PRPs to submit additionaltechnical information in support of an alternative cover design. Selection of the final coverdesign will be based on a demonstrated ability to satisfy the state’s landfill cover performancestandards as set forth in Nebraska regulations, Title 118, Groundwater Quality Solid Standardsand Title 132, Integrated Solid Waste Management Regulations and will be evaluated againstEPA’s (nine) remedy selection evaluation criteria.

Institutional Controls

A number of comments were made, both pro and con, on the use of institutional controls toprevent exposures to contaminated groundwater.

Institutional Controls are an integral component of the remedy for the South Landfill.Institutional Controls generally consist of non-engineering measures intended to prevent orreduce exposure to hazardous substances. They would include measures that are consistent withthe anticipated future land use and conducted in a manner to assure that the remedy remains

3

protective of human health and the environment. The city of Hastings is in process of enacting azoning ordinance which would require an application and registration process for private wells .The EPA supports the city’s efforts to enact this ordinance to reduce or prevent human exposureto contaminated groundwater in the Hastings Institutional Controls Area in conjunction with theentire remedial strategy for the South Landfill.

WRITTEN COMMENTS FROM THE PRINCIPLE RESPONSIBLE PARTIES

Landfill Phytocap

The PRPs submitted written comments in support of the Phytocap Landfill Cover Alternative.The Phytocap was promoted as an effective, but less costly alternative to traditional landfill coverdesigns. In addition, the PRPs requested EPA’s consideration of a performance-based ROD for thesource control remedy without specifying the process option that must be used.

Surface water controls and GCL (or alternative) landfill cap is selected as the remedythat minimizes exposure to landfill contents and provides the most reduction in infiltrationthrough the landfill to ground water. In response to public comment, EPA in consultation withNDEQ will evaluate additional information on an alternative cap to determine if the alternativecap will meet the equivalent protection standards of Title 132-Integrated Solid WasteManagement Regulations; will meet the source control remedial action requirements of Title118-Groundwater Quality Standards, and satisfies EPA’s (nine) remedy selection criteria.

Contrary to statements made by the PRP’s, EPA has been unable to confirm that a“Phytocap” design, similar to the one proposed by the PRP’s for South Landfill, has beenapproved by EPA at any of the sites identified by the PRPs in their written comments.

The PRPs submitted written comments questioning the GCL cost estimate included in the FSAddendum.

The EPA has revised the cost estimate for the GCL alternative consistent with the costestimates for the other alternatives and presented this information in this Record of Decision.

The cost estimate used in this ROD is based on the assumption, presented in the FSprepared by the PRP Group, that the landfill area will require a cover 27 acres in size. A moreaccurate estimate will likely be developed during the remedial design phase. A larger area willresult in proportionally higher costs for all landfill cover alternatives.

4

OTHER WRITTEN COMMENTS

Written comments were received from a local citizen who questioned the intention and effect ofthe institutional controls proposed by the city.

Institutional controls and the proposed institutional control ordinance are intended toprevent exposure to contaminated water until cleanup goals are achieved. Institutional controlsare not intended as a mechanism to shift responsibility of cleanup from the PRPs to propertyowners. The EPA requires that the responsible parties retain the burden of remediatingcontamination problems for which they are responsible. Affected property owners may beadversely affected until cleanup goals are achieved. The proposed institutional control area(ICA) will be required until cleanup goals are achieved to prevent exposure to contaminatedwater. Once cleanup goals are achieved, the ICA can be dissolved.

An extension of the municipal water supply is not a component of this project and EPAwill not require connection to the municipal water supply system. Annexation is not arequirement of, or at component of, this project.

Property owners who have contaminated drinking water above recommended drinkingwater limits which is attributable to the site will be offered an alternative water supply for theduration of the project.

Written comments were received from the U.S. Fish and Wildlife Service and the NebraskaState Historical Society in support of the project.

The EPA will notify the State Historical Society if unsuspected historical remains areuncovered during the project. The EPA will take action to ensure that proposed actions will notadversely impact nearby wetland areas.

HASTINGS GROUNDWATERCONTAMINATION

SOUTH LANDFILL SUBSITE

SUPERFUND SITE

HASTINGS, NEBRASKA

REMEDIALADMINISTRATIVE

RECORD

MARCH 2000

VOLUME I

REGION VIISUPERFUND DIVISIONU.S. ENVIRONMENTALPROTECTION AGENCY

HASTINGS GROUNDWATER CONTAMINATIONSOUTH LANDFILL SUBSITE

REMEDIAL ADMINISTRATIVE RECORD

INTRODUCTION

This index of documents for the administrative recorddescribes documents considered by the U.S. EnvironmentalProtection Agency during the remedial action with respect tothe South Landfill Site.

The administrative record addendum index lists documentschronologically in ascending order, with any undated documentsfollowing all dated entries. This sorting scheme correspondswith the arrangement of the documents in the record itself. Incases where documents contain only partial dates, the indexdefaults to the first month of the year and/or first day ofthe month, as appropriate.

Most of the documents described in the administrative recordindex are present in hard copy form in the record itself:those marked “YES” under the REFERENCE field have beenincorporated in the record by reference, and may be availablefor review at the EPA Region VII office during regularbusiness hours.

All documents included in the Compendium of CERCLA ResponseSelection Guidance Documents revised in March 1991, are herebyincluded in the administrative record addendum by Reference.All previous administrative records are also included byreference.

The administrative record is available for public review atEPA’s Region VII Office, 726 Minnesota Avenue, Kansas City,Kansas, 66101. Questions concerning the administrative recordshould be addressed to the EPA Administrative RecordCoordinator.

The administrative record is required by the ComprehensiveEnvironmental Response, Compensation, and Liability Act(CERCLA), as amended by the Superfund Amendments andReauthorization Act (SARA).

HASTINGS GROUNDWATER CONTAMINATIONSOUTH LANDFILL SUBSITE

REMEDIAL ADMINISTRATIVE RECORD

TABLE OF CONTENTS

VOLUME I

3.0 Remedial Investigation (RI)

3.1 Correspondence3.3 Sampling and Analysis Data

VOLUME II


3.3 Sampling and Analysis Data

11.0 Potentially Responsible Party (PRP)

11.6 PRP-Specific Correspondence

VOLUME III


3.5 Remedial Investigation (RI) Report

VOLUME IV


3.7 Health and Endangerment Assessments

1

DOCUMENT DATE: 01/23/94NUMBER OF PAGES: 3AUTHOR: Wagoner, David A., Director, Waste Management

DivisionCOMPANY/AGENCY: U.S. Environmental Protection Agency, Region

VIIRECIPIENT: David Fishesr, Dunmire,Fisher & HastingsDOCUMENT TYPE: CorrespondenceREFERENCE: NoDOCUMENT TITLE: Letter re: “Notice of Potential Liability”CATEGORY: 11.6


DivisionCOMPANY/AGENCY: U.S. Environmental Protection Agency, Region

VIIRECIPIENT: James J. Puhala, Vice President, General Counsel &

Secretary, Dravo CorporationDOCUMENT TYPE: CorrespondenceREFERENCE: NoDOCUMENT TITLE: Letter re: “Notice of Potential Liability”CATEGORY: 11.6


DivisionCOMPANY/AGENCY: U.S. Environmental Protection AgencyRECIPIENT: Charles D. Meyer, Registered Agency, Concrete

Industries, Inc.DOCUMENT TYPE: CorrespondenceREFERENCE: NoDOCUMENT TITLE: Letter re: “Notice of Potential Liability”CATEGORY: 11.6


DivisionCOMPANY/AGENCY: U.S. Environmental Protection AgencyRECIPIENT: Michael E. Sullivan, City Attorney, City of

Hastings,Nebraska

DOCUMENT TYPE: CorrespondenceREFERENCE: NoDOCUMENT TITLE: Letter re: “Notice of Potential Liability”CATEGORY: 11.6

DOCUMENT DATE: 01/27/94NUMBER OF PAGES: 1AUTHOR: Hewitt, James W., Attorney at LawCOMPANY/AGENCY:RECIPIENT: David A. Wagoner, Director, Waste Management

Division, Environmental Protection AgencyDOCUMENT TYPE: CorrespondenceREFERENCE: NoDOCUMENT TITLE: Letter re: “Concrete Industries, Inc.,

Response to EPA’s Letter of PotentialLiability”

CATEGORY: 11.6

2

DOCUMENT DATE: 02/01/94NUMBER OF PAGES: 54AUTHOR:COMPANY/AGENCY: Morrison Knudsen CorporationRECIPIENT: U.S. Environmental Protection Agency DOCUMENT TYPE:REFERENCE: NoDOCUMENT TITLE: Entitled: “South Landfill Soil Gas

Investigation Approach”CATEGORY: 3.3

DOCUMENT DATE: 09/30/94NUMBER OF PAGES: 253AUTHOR:COMPANY/AGENCY: Morrison KnudsenRECIPIENT: USEPA-Region VIIDOCUMENT TYPE: ReportREFERENCE: NoDOCUMENT TITLE: Entitled: “Soil Gas Investigation Report”CATEGORY: 3.3

DOCUMENT DATE: 04/01/95NUMBER OF PAGES: 171AUTHOR:COMPANY/AGENCY: Morrison Knudsen CorporationRECIPIENT: USEPA-Region VIIDOCUMENT TYPE: ReportREFERENCE: NoDOCUMENT TITLE: Entitled: “Remedial Investigation/Feasibility

Study Field Investigation, Part 1 Work Planfor South Landfill, Operable Unit #5"

CATEGORY: 3.3

DOCUMENT DATE: 04/25/95NUMBER OF PAGES: 2AUTHOR:COMPANY/AGENCY: U.S. Environmental Protection Agency - Region

VIIRECIPIENT:DOCUMENT TYPE: ASR FormREFERENCE: NoDOCUMENT TITLE: Entitled: Analytical Services Request Form

for Activity #CS5MG”CATEGORY: 3.3

3

DOCUMENT DATE: 06/01/95NUMBER OF PAGES: 1AUTHOR:COMPANY/AGENCY: U.S. Environmental Protection Agency-Region

VIIRECIPIENT:DOCUMENT TYPE: Chain of CustodyREFERENCE: NoDOCUMENT TITLE: Entitled “Chain of Custody Record for

Activity #CS5MG and CS6MG”CATEGORY: 3.3


VIIRECIPIENT:DOCUMENT TYPE: Chain of CustodyREFERENCE: NoDOCUMENT TITLE: Entitled: “Chain of Custody Record for

Activity #CS7S2"CATEGORY: 3.3

DOCUMENT DATE: 08/01/95NUMBER OF PAGES: 98AUTHOR:COMPANY/AGENCY: Morrison Knudsen CompanyRECIPIENT: USEPA-Region VIIDOCUMENT TYPE: ReportREFERENCE: NoDOCUMENT TITLE: Entitled “Well Installation Technical

Memorandum for South Landfill, Operable Unit#5"

CATEGORY: 3.3


VIIRECIPIENT:DOCUMENT TYPE: Data TransmittalREFERENCE: NoDOCUMENT TITLE: re: ”Activity #CS7MG”CATEGORY: 3.3

4

DOCUMENT DATE: 10/11/95NUMBER OF PAGES: 9AUTHOR: Berglund, Peter R., Subsite ManagerCOMPANY/AGENCY: Morrison KnudsenRECIPIENT: Darrell Sommerhauser, USEPA-Region vIIDOCUMENT TITLE: CorrespondenceREFERENCE: NoDOCUMENT TITLE: Letter re: “Transmitting Memorandum Regarding

the October 1995 Groundwater Sampling at theSouth Landfill Subsite, Making Up Part of theOctober 1995 Quarterly Sampling Plan”

CATEGORY: 3.3

DOCUMENT DATE: 10/16/95NUMBER OF PAGES: 3AUTHOR: Gomez, Brenda, Quarterly Sampling ManagerCOMPANY/AGENCY: Morrison KnudsenRECIPIENT: Darrell Sommerhauser, USEPA-Region VIIDOCUMENT TYPE: CorrespondenceREFERENCE: NoDOCUMENT TITLE: Letter re: ”Exception Memorandum-October 1995

Water Level Measurements at the ColoradoAvenue and South Landfill Subsites”

CATEGORY: 3.3

DOCUMENT DATE: 01/11/96NUMBER OF PAGES: 6AUTHOR: Berglund, Peter R., Subsite ManagerCOMPANY/AGENCY: Morrison Knudsen CorporationRECIPIENT: Mr. Ronald King, EPA Region VIIDOCUMENT TYPE: MemorandumREFERENCE: NoDOCUMENT TITLE: re: ”January 1996 Ground Water Sampling”CATEGORY: 3.3

DOCUMENT DATE: 02/02/96NUMBER OF PAGES: 4AUTHOR: Berglund, Peter R., Subsite ManagerCOMPANY/AGENCY: Morrison Knudsen CorporationRECIPIENT: Mr. Ronald King, EPA Region VIIDOCUMENT TYPE: MemorandumREFERENCE: NoDOCUMENT TITLE: Subject re: “Exception Memorandum-January

1996 South Landfill Ground Water Sampling,Hastings Ground Water Contamination Site,Hastings, Nebraska”

CATEGORY: 3.3

5

DOCUMENT DATE: 02/12/96NUMBER OF PAGES: 24AUTHOR: Jirka, Andrea, Program Manager, Regional LaboratoryCOMPANY/AGENCY: United States Environmental Protection AgencyRECIPIENT: Ron King, SUPRDOCUMENT TYPE: MemorandumREFERENCE: NoDOCUMENT TITLE: Subject re: “Data Transmittal for Activity

#DL2MG”CATEGORY: 3.3

DOCUMENT DATE: 02/23/96NUMBER OF PAGES: 2AUTHOR: King, RonCOMPANY/AGENCY: U.S. Environmental Protection AgencyRECIPIENT:DOCUMENT TYPE: DataREFERENCE: NoDOCUMENT TITLE: Entitled: “Hastings South Landfill, Water

Quality Data”CATEGORY: 3.3

DOCUMENT DATE: 03/12/96NUMBER OF PAGES: 5AUTHOR: Berglund, Peter R.COMPANY/AGENCY: Morrison Knudsen CorporationRECIPIENT: Ronald KingDOCUMENT TYPE: MemorandumREFERENCE: NoDOCUMENT TITLE: Subject re: “Memorandum Transmitting

Photographs of the South Landfill Wellsduring Installation and Current Condition(February 23, 1996) of the Wells, SouthLandfill Subsite, Hastings Nebraska”

CATEGORY: 3.3

DOCUMENT DATE: 12/01/96NUMBER OF PAGES: 392AUTHOR:COMPANY/AGENCY: Morrison Knudsen CorporationRECIPIENT:DOCUMENT TYPE: ReportREFERENCE: NoDOCUMENT TITLE: Entitled: “Remedial Investigation Report ,

South Landfill Subsite”CATEGORY: 3.5

DOCUMENT DATE: 11/01/97NUMBER OF PAGES: 239AUTHOR:COMPANY/AGENCY: Nebraska Health and Human Services System,

Department of Regulation & LicensureRECIPIENT:DOCUMENT TYPE: ReportREFERENCE: NoDOCUMENT TITLE: Entitled: “Human Health Baseline Risk

Assessment, Hastings Area-Wide GroundwaterContamination Site”

CATEGORY: 3.7

DOCUMENT DATE: 11/21/97NUMBER OF PAGES: 3AUTHOR: King, Ronald, P.E., Remedial Project ManagerCOMPANY/AGENCY: United States Environmental Protection AgencyRECIPIENT: Mr. William Allen, Assistant Regional

Environmental Assessment Officer, U.S. Dept. ofInterior

DOCUMENT TYPE: Correspondence With AttachmentREFERENCE: NoDOCUMENT TITLE: re: “Concurrence on the Risk Assessment”CATEGORY: 3.7

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