INTERIM RECORD OF DECISIONOflter.

93?

HASTINGS GROUND WATER CONTAMINATION SITESECOND STREET SUBSITE, OPERABLE UNIT #20

HASTINGS, NEBRASKA

Prepared by

U S Environmental Protection AgencyRegion VII

901 North 5th StreetKansas City, Kansas 66101

July 2003

40100787

SUPERFUND RECORDS

RECORD OF DECISIONDECLARATION

SITE NAME AND LOCATION

Hastings Ground Water Contamination SiteSecond Street Subsite Operable Unit #20Hastings NebraskaCERCLIS ID# NTD980862668

STATEMENT OF BASIS AND PURPOSE

The U S Environmental Protection Agency (EPA) has prepared this decision documentto present the selected remedial action for the Second Street Subsite Operable Unit (OU) #20 ofthe Hastings Ground Water Contamination site located in Hastings Nebraska This decision waschosen in accordance with the Comprehensive Environmental Response Compensation andLiability Act (CERCLA) as amended, and the National Contingency Plan (NCP) This decisionis based on the Administrative Record for this site The Administrative Record file is located mthe following information repositories

Hastings Public Library U S Environmental Protection Agency517 West 4th Street 901 North 5th StreetHastings Nebraska Kansas City Kansas

The EPA has coordinated selection of this remedial action with the Nebraska Departmentof Environmental Quality (NDEQ) The state of Nebraska concurs with the selected remedy

ASSESSMENT OF THE SITE

The response action selection in the Record of Decision (ROD) is necessary to protect thepublic health or welfare or the environment from actual or threatened releases of hazardoussubstances into the environment

DESCRIPTION OF THE SELECTED REMEDY

The selected remedy prevents further migration of the contaminated ground water plumecontains the contaminated ground water in order to reduce risk and will contribute to achievingthe long term objectives of reducing the contaminant levels in the ground water to belowregulatory and/or health based levels and prevent further degradation to the aquifer provided it iscombined with a suitable remedy for the subsite source area (Operable Unit #12) The selectedremedy includes the following components

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combined with a suitable remedy for the subsite source area (Operable Unit #12) The selectedremedy includes the following components

Extraction of ground water combined with treatment by granular activated carbonIn situ biotreatment adding oxygen release compounds to the aquiferContinued operation of the source area pump and treat and soil vapor extractionsystemsContinued operation of the Pine Avenue in well aeration treatment system andLong term ground water monitoring of the effectiveness of the above systems

STATUTORY DETERMINATIONS

This interim action is protective of human health and the environment in the short termand is intended to provide adequate protection until a final action ROD is signed Although thisis an interim action and therefore is not required to comply with those federal and staterequirements that are applicable or relevant and appropriate (ARARs) it is the goal of thisremedy when combined with a suitable remedy for the subsite source area (OU #12) that cleanup to ARARs will be achieved This action is cost-effective Although this action is notintended to address fully the statutory mandate for permanence and treatment to the maximumextent practicable this action does utilize treatment and thus supports that statutory mandateBecause this action does not constitute the final remedy for the subsite the statutory preferencefor remedies that employ treatment that reduces toxicity mobility or volume as a principalelement although partially addressed in this remedy will be addressed by the final responseaction Subsequent actions may be needed to address fully the threats posed by conditions at thissubsite

Because this remedy will result in hazardous substances remaining on site above levelsthat allow for unlimited use and unrestricted exposure a review will be conducted within fiveyears after initiation of the remedial action to ensure that the remedy continues to provideadequate protection of human health and the environment Because this is an interim actionROD review of this subsite and remedy will be ongoing as the EPA continues to developremedial alternatives for the other operable unit in this subsite Operable Unit #12

ROD DATA CERTIFICATION CHECKLIST

The following information is included in the Decision Summary section of this RODAdditional information can be found in the Administrative Record file for this site

Contaminants of concern (COCs) and their respective concentrationsBaseline risk represented by the COCsClean up levels established for COCs and the basis for the levelsThe degree to which source materials constituting principal threats are addressedCurrent and reasonably anticipated future land use assumptions and current and potentialfuture beneficial uses of ground water used in the baseline risk assessment and the ROD

Potential land and ground water use that will be available at the site as a result of theselected remedyEstimated capital operation and maintenance, and total present worth costs discount rateand the number of years over which the remedy cost estimates are projectedKey factors that led to selecting the remedy

TaprayAttmg DirectorSuperfund DivisiorU S EPA" Region VII

Date / /

INTERIM RECORD OF DECISIONDECISION SUMMARY

1 0 Site Name, Location, and Description

This Record of Decision (ROD) has been developed by the United States EnvironmentalProtection Agency (EPA) to select a remedial alternative at the Second Street subsite OperableUnit (OU) #20 of the Hastings Ground Water Contamination site in Hastings Nebraska (hereinthe subsite ) The Comprehensive Environmental Response Compensation and LiabilityInformation System (CERCLIS) identification number for the subsite is NTD980862668 TheEPA is the lead agency for the activities taking place at the Second Street subsite

The Hastings Ground Water Contamination Site (HGWCS) is located in Adams and ClayCounties in Nebraska The HGWCS is also known as the Hastings Superfund site The EPA hasdesignated seven subsites of the Hastings Superfund site Some of these subsites have beenfuther broken down into operable units Each subsite is an area where volatile chemicalcontaminants (VOCs) were released and have entered the local ground water aquifer although atsome subsites other contaminants are present as well The city of Hastings (herein the "city )began taking public water supply wells out of service after contamination was discovered inwells located in old industrial areas along the Burlington Northern Railroad (BNRR) right ofway In 1983 the Nebraska Department of Health (NDOH) sampled the Hastings public watersupply system in response to citizen complaints of foul taste and odor in the drinking waterThat same year the NDOH and the Nebraska Department of Environmental Quality (NDEQ)began investigating wide spread ground water contamination in the Hastings area Eventuallythree city operated water supply wells Numbers 3 10 and 12 were taken out of service andothers were placed on standby status

A second public water supplysystem run by Community MunicipalServices, Inc (CMS) supplied customerseast of the city limits of Hastings Two ofthe three CMS system supply wells werealso taken out of service due tocontamination

The Second Street subsite shownin Figure 1 is a former manufactured gasplant (FMGP) which operated frombefore the turn of the century until about1931 Following the availability ofnatural gas the plant wasdecommissioned and subsequentlydemolished Residues from the gas Figure 1

manufacturing processes commonly referred to as coal tar, were left on site and resulted in soiland ground water contamination The FMGP property is located immediately east of theHastings downtown corridor and abuts the BNRR and the former Union Pacific Railroad(UPRR) right of way The FMGP occupied an area consisting of one half of a city block Thisis also referred to as the FMGP source area in this ROD The local surface topography isrelatively flat and the approximate elevation is 1 920 feet above mean sea level Based uponinformation from investigations at the subsite it is believed that the Second Street subsite plumeof contaminated ground water extends eastward and travels beneath commercial and residentialareas for a distance of approximately 3 000 feet

2 0 Site History and Enforcement Activities

The EPA began investigating sources of ground water contamination in the Hastings areain 1984 and proposed the site for listing on the National Priorities List (NPL) at that time TheNPL is a nationwide list of hazardous waste sites that are eligible for investigation andremediation under the Superfund Program Due to the high levels of VOCs found in threemunicipal wells the EPA designated the contaminated area as the Hastings Ground WaterContamination site and placement on the NPL became final in 1986

During the early 1990s Nebraska s Leaking Underground Storage Tank (LUST) programoversaw investigations of a gasoline service station located just to the east of the FMGPproperty This LUST site is referred to as the Foote Oil site The Foote Oil site investigationconfirmed the presence of gasoline contamination in soil and ground water Several of theconstituents of gasoline, specifically benzene toluene ethylbenzene and xylene (collectivelyreferred to as BTEX) are also found in FMGP wastes Therefore the plumes have been difficultto distinguish except that 1,2-dichloroethane (1,2 DCA) appears to be associated only withpetroleum contamination not with the FMGP property The Comprehensive EnvironmentalResponse Compensation and Liability Act (CERCLA) has an exclusion with respect toaddressing petroleum or gasoline contamination The state's LUST program addressescontamination at petroleum facilities Therefore the action described in this ROD will notaddress the petroleum source and will address the Foote Oil contamination only incidentally, thatis to the extent that it is already commingled with the contaminated ground water plumeemanating from the FMGP property

In November 2000 the city, in City Ordinance No 3754 created the Institutional ControlArea (ICA) The entire area currently affected by the Second Street contaminated ground waterplume is believed to be located within the ICA These controls include requirements for wellregistration limited water usage from existing wells, and penodic analysis The city administersthe ICA program and provides results of laboratory testing and related information to propertyowners However the ICA does nothing to limit the migration of the contaminated ground wateror restore this resource to a beneficial use

Some reports indicate that manufacture of coal gas at 109 West Second Street began m1894 The facility was identified on 1894 fire insurance maps as the Hastings Gas WorksRecords indicate the FMGP was owned by at least four different companies The last ownerCentral Power Company, ceased operations at the plant in 1931 The expanding demand for fuelwas met by natural gas being delivered to Hastings by pipeline There are no known successorsto any of the former operators of the FMGP

The FMGP property was acquired by the city in 1942 The city Gas Department utilizedthe property for operation of the natural gas delivery system The old buildings and otherstructures were eventually demolished The city constructed a new building on the northernportion of the property m 1948 or 1949 This building was used by the city Gas Department andlater in 1954 became the Hastings Police Station Hastings Utilities constructed the Minnesotaelectrical substation on the southern part of the property m 1969 An animal shelter wasconstructed on the west side of the property in 1976 Most of the remaining portions of theproperty are paved and have been used for parking In June 2001 the Hastings PoliceDepartment relocated to a new building several blocks away The old police station is utilizedintermittently for storage and other varied purposes The property is fenced and normally themam gates are locked when city employees are not working at the property

Complaints of poor water quality from the municipal water system were first filed in1944 shortly after the installation of Municipal Well Number 18 City records indicate that WellNumber 18 was taken out of service at that time This well is located along the BNRR right ofway, just west of Elm Avenue at a distance of about 2 500 feet from the FMGP source area In1953 this well was again tested and found to be contaminated unfit for use and therefore wasnot placed into regular service In 1983 the city fitted this well with a pump and attempted toplace it in service orf an experimental basis However residents immediately reported a foultaste and odor in the municipal water supply In March April and May 1983 water samplescollected by state employees showed the presence of high levels of tnchloroethylene (TCE)contamination and relatively lower levels of five other chlorinated solvent chemicals Inaddition the sample collected on May 24 1983 also contained approximately four microgramsper liter (ug/1) of benzene The presence of benzene is consistent with the possibility that WellNumber 18 was contaminated by wastes originating from the old gas works property

In 1988 the EPA installed a ground water monitoring well on the UPRR right of-waywhich adjoins the eastern boundary of the FMGP property During construction of this wellidentified as MW 9 a strong petroleum odor was noted Although MW 9 was intended to definethe northern extent of the Colorado Avenue subsite TCE plume due to the presence of highlevels of BTEX it became the basis for initiating a remedial investigation of the FMGP propertyIn addition to the BTEX contaminants sampling of MW 9 during 1988 and 1989 identified thepresence of styrene and polycychc aromatic hydrocarbon (PAH) compounds in the ground waterThe five PAHs found at greatest concentrations were naphthalene 2 methylnaphthaleneacenaphthylene fluorene and phenanthrene All of these contaminants are commonly associatedwith FMGP wastes

In 1993 the EPA installed three monitoring wells and also sampled the Foote Oil LUSTsite monitoring wells In January 1997 a removal action near the source area for the SecondStreet subsite began operation This removal action consists of ground water extraction withcarbon treatment and vadose zone contaminant removal by soil vapor extraction (SVE) Thevadose zone is the unsaturated portion of the subsurface This removal action was intended tostabilize subsite conditions and continues to operate During construction of the removal actionsystems additional investigations of on site soil and ground water were performed The presenceof BTEX and PAHs indicated that wastes remaining from the FMGP at the subsite hadcontaminated the soil and the ground water

In 1999 under the supervision of the NDEQ LUST Program an action to address vadosezone contaminants through SVE was initiated at the Foote Oil Site That action is ongoing

The EPA installed additional monitoring wells at Pine Avenue California Avenue CedarAvenue and Elm Avenue Figure 2 illustrates the locations of several of the subsite momtonngwells During the period of 1997 2000 extensive momtonng of the ground water downgradientof the source area was performed Based on these sampling results the benzene and naphthalene

DOWN GRADIENT GROUNDWATERREMOVAL ACTION

M 07 (12 0 N O R I )FOOTE OIL PROPERTY

ESTIMATEDEXTENT OF PLUME

SECOND STREETSUBSITE

SW BS D

BURLINGTON NORTHERN

SOURCE AREA GROUNDWATERREMOVAL ACTION

COLORADOAVENUE SUBSITE

plume has been determined to extend approximately 3,000 feet from the FMGP source areaThis highlighted the need for additional response action

In 2001 to supplement the FMGP source area removal action a downgradient groundwater removal action was implemented approximately 700 feet to the east of the FMGP sourcearea This action uses m well aeration (IWA) to help reduce contamination in the ground water

For this in well aeration system a compressor blows compressed air into two existing wells toseparate VOCs from the ground water The VOCs are then removed from the gaseous phaseusing granulated activated carbon (GAC)

Documents in the Administrative Record file may be reviewed for a more completesource of information regarding the history of the site

3 0 Community Participation

Throughout the time that investigation and removal activities have taken place at the sitenumerous community involvement activities have occurred These include the distribution offact sheets meetings with the public and media interviews The Engineering Evaluation/CostAnalysis (EE/CA) was made available for public comment in 1995 prior to the EPA making afinal decision regarding the first removal action at this subsite A second EE/CA was madeavailable for public comment in 1999 prior to the EPA making a final decision regarding thesecond removal action at this subsite

The EPA issued a Proposed Plan for OU #20 of the Second Street subsite on October 52002 A 30 day public comment period occurred from October 5 to November 5 2002 Apublic meeting was held on October 17 2002 at the Hastings Public Library in HastingsNebraska to present the Proposed Plan and solicit comments from the public The EPA sresponse to comments received during the comment period is included in the ResponsivenessSummary which is a part of this ROD Additionally the EPA established an AdministrativeRecord which contains supporting documents for this decision The Administrative Record isavailable for review during normal business hours at the following locations

Hastings Public Library U S Environmental Protection Agency517 West 4th Street 901 North 5th StreetHastings Nebraska Kansas City Kansas

4 0 Scope and Role of Response Action

As with many Superfund sites the problems with the Hastings Ground WaterContamination site are complex As a result the EPA has organized the work into sevensubsites, many of which have been further divided into operable units The Second Street subsiteis comprised of two operable units OU #12 is the FMGP source area and OU #20 is thecontaminated ground water plume downgradient from the source area The action for OU #20 ofthe Second Street subsite will complement and be consistent to the extent possible withresponse actions underway or planned at the other HGWCS subsites

The common goals for the entire HGWCS are to contain and remove contaminants in theground water and reduce cancer risk levels to correspond to no more than an estimated oneadditional cancer case in a population of 1 000 000 based on an assumed 30 year exposureperiod The objectives for the remedial action for OU #20 of the Second Street subsite whichsupport these common goals for the entire HGWCS, are

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To prevent further migration and further worsening of the downgradient plume

To remediate or contain the contaminated ground water in order to reduce risk

To provide a remedy which will achieve the long term objectives listed belowprovided it is combined with a suitable remedy for the source area (OU #12) TheEPA anticipates that the source area will be the subject of a separate ROD at alater date

The long term objectives for this subsite are

To reduce the contaminant levels in the ground water to levels less than maximumcontaminant levels (MCLs) and the maximum contaminant level goals (MCLGs)if they are greater than zero pursuant to the Safe Drinking Water Act and/or tostate clean up levels derived from Nebraska Title 118 regulations or to levelswhere the excess cancer risk is computed as being less than one additional cancerper million persons of population (1 x 106) or where the Hazard Index is less than1 0 so that the aquifer can be restored to its beneficial use

To prevent further degradation of the ground water

5 0 Site Characteristics

The Second Street subsite consists of 1) contaminated soil acting as the source at theFMGP property, and 2) the contaminated ground water plume underlying the contaminated soiland extending east of the source area for a distance of about 3 000 feet Sampling of the soil andground water indicates the presence of benzene toluene, ethylbenzene and xylene (BTEX) othervolatile organic compounds (VOCs) and polycychc aromatic hydrocarbons (PAHs) Two ofthese contaminants benzene and napthalene are highly mobile in ground water and are presentin the full length of the contaminated ground water plume Certain compounds, such as thePAHs other than napthalene are less mobile and are not likely to migrate as far in the groundwater Further characterization of the extent of contamination in the ground water will beperformed during the remedial design and remedial action

Subsite Source Area Characteristics

Although removal actions to address contamination near the source area are ongoing andwill be integrated into the selected remedy in this interim action ROD additional source controlmeasures will be needed before the remedial objectives can be fully achieved These additionalmeasures are beyond the scope of this interim action ROD Table 1 gives information about themaximum concentrations found in soil for some of the subsite contaminants

TABLE 1SOIL SAMPLE DATA

Contaminants/Maximum Concentrations

VolatileContaminants

benzene

toluene

ethylbenzene

xylene

styrene

MaximumConcentration

257 mg/kg*

761 mg/kg

757 mg/kg

961 mg/kg

640 mg/kg

PAHContaminants

naphthalene

2 methylnaphthalene

acenaphthylene

phenanthrene

pyrene

MaximumConcentration

2300 mg/kg

7800 mg/kg

1200 mg/kg

1 700 mg/kg

11 00 mg/kg

*mg/kg milligrams per kilogram

Note In addition to the PAHs listed above the following PAHs were found in soil samples at levels below1000 mg/kg and above 100 mg/kg anthracene fluoranthene benzo(a)anthracene chrysene

benzo(b)fluoranthene benzo(k)fluoranthrene benzo(g h i)perylene and mdeno(l 2 3 cd)pyrene

The values shown in Table 1 represent the concentrations of some of the contaminantsfound in soil samples collected by the EPA from the FMGP property The presence ofcontaminants in soil samples may or may not pose a threat to ground water quality Some of thecontaminants are more likely to adhere to soil and therefore are not as likely to be found in theground water as the other more mobile contaminants The water table in Hastings isapproximately 120 feet below the ground surface

This ROD addresses the contaminated ground water plume downgradient from the FMGPsource area The EPA recognizes that future evaluation and action will be needed to address thesoil contamination in the FMGP source area and the ground water that it affects west of PineAvenue The FMGP source area is referred to as OU #12

In general, infiltration of surface water within the FMGP property is limited due to thebuildings and concrete parking lot which cover most of the land area This limits the movementof additional contaminants through the soil into the ground water On the other hand theadjoining property to the east the former Union Pacific Railroad (UPRR) right of way is notpaved, and slopes to the east Runoff waters from the UPRR right of way can travel through thesoil of the neighboring properties and eventually enter the aquifer The infiltration of this surfacewater provides a driving force allowing contaminants to travel through the soil and beintroduced into the ground water

Hastings is located in a semi and climate zone and the annual rainfall tends to beconcentrated during the spring and fall seasons Studies of rainfall infiltration have concludedthat recharge amounts to only a few inches per year This finding suggests that most recharge ofthe local aquifer occurs from water originating in areas to the west of Hastings While this factor

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also suggests that water transport of the contamination is less of a factor than might be the case atsome other Superfund sites studies of organic solvents have shown that such contaminants travelreadily through dry soil in the vadose zone even when clay sediments are present

Current conditions at portions of the source area limit access to city employees only Thismeans that at these locations disruption of existing concrete and asphalt cap materials is less of aconcern than would otherwise be the case

Ground Water Characteristics Characteristics of the Downgradient Plume

During operation of the FMGP wastes containing BTEX and PAHs were disposed and/orreleased on site Additionally gasoline components including BTEX and 1 2 DCA werereleased to the vadose zone from the nearby Foote Oil property These contaminants have sincemigrated vertically into the deeper vadose zone and have entered the underlying aquifer Oncethe contaminants entered the aquifer they migrated primarily in the direction of ground waterflow which is toward the east

Data from the monitoring wells depicted in Figure 2 were used to characterize andevaluate the Second Street subsite contaminated ground water plume Wells installed by theEPA downgradient from the FMGP and located within the primary flowpath include S W 1SW 3 SW 4S SW 51 SW 61 SW 71, SW 81 In addition monitoring wells installed during theFoote Oil LUST site investigation have been sampled and the results used to establish betterdefinition of the overall contaminant plume A summary of the highest concentrations ofselected contaminants found in ground water samples prior to implementation of the source areaground water removal action in January 1997 is provided in Table 2 The MCLs pursuant to theSafe Drinking Water Act for public water supplies are provided for comparison purposes TheMCLs represent levels which are considered safe for human consumption

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TABLE 2GROUND WATER SAMPLE DATA

Compound

Benzene

Toluene

Ethylbenzene

Xylene

Naphthalene

1 2 DCA

Maximum Cone (in ug/1) Well

WesternPlume

25000

28000

19000

12000

24000

1 700

Eastern WesternPlume Plume

6700 HWS 5

2500 HWS 2

480 HWS 2

1100 HWS 2

12000 MW9

970 HWS 5

Well locations reflect western/eastern plume areas Well HWS 14 is located eastWells SW 5S and SW 51 are located east of Pine Avenue at California AvenueMCL Maximum Contaminant Levels (EPA Drinking Water Regulations)ug/1 micrograms per liter

Well

EasternPlume

HWS 14

HWS 14

HWS 14

HWS 14

SW5I

SW 5S

MCL(in ug/1)

5

1 000

700

10000

notestablished

5

of Pine Avenue

Early reports published by the EPA show incomplete information about the extent ofground water contamination east of the FMGP As a result of data from additional wells sampledfrom 1997 to 2000, the benzene and naphthalene plumes were better defined Figure 3 indicatesthe known extent of the benzene and naphthalene ground water contamination based on samplescollected during that period The 1997 to 2000 data disclosed that the benzene and naphthaleneplume is much longer than was previously known The ground water plume to be addressed bythe selected remedy in this ROD extends approximately 3 000 feet eastward from the FMGPsource area Additional monitoring may be conducted during the design of this remedial actionto further delineate the extent of ground water contamination

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SOURCE AREA PUMPAND TREAT SYSTEM

EASTERN PORTION OF THEDOWNGRADIENT PLUMF

TAIL PORTION OF THE EASTERNDOWNGRADIENT PLUME

WESTERN PORTION OF THEDOWNGRADIENT PLUME

PINE AVE DOWNGRADIENTREMOVAL ACTION SYSTEM

Figure 3

6 0 Current and Potential Future Subsite and Resource Uses

6 1 Land Uses

The land usage in the area of the downgradient contaminated ground water plume, is amix of commercial and residential properties It is anticipated that the land usage will remainmuch the same in the future As has been mentioned previously in this ROD other contaminatedsites exist in the vicinity of this subsite The Foote Oil LUST site is the nearest but the ColoradoAvenue subsite is also nearby Refer to Figure 2 for the location of these sites

6 2 Ground Water Uses

Municipal wells m the area of the subsite have been taken out of service by the cityResidents in the affected area are serviced by the municipal water supply Also m November2000 the city in City Ordinance No 3754, created the Institutional Control Area (ICA) The areacurrently affected by the Second Street contaminated ground water plume is located within theICA These controls include requirements for well registration limited water usage fromexisting wells, and periodic analysis The city administers the ICA program and provides resultsof laboratory testing and related information to property owners However the ICA does nothingto limit the migration of the contaminated ground water or restore this resource to a beneficialuse

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The goals of this remedial action at this subsite are to prevent further migration of thecontaminated plume and contain the contaminated ground water while contributing to achievingthe long term objectives of reducing contaminant levels in the ground water to below regulatoryand/or health based levels Ground water monitoring will be conducted to ensure that theremedy is effective in addressing the contamination in the ground water

70 Summary of Subsite Risks

CERCLA requires the EPA to seek permanent solutions to protect human health and theenvironment from hazardous substances to the extent practicable These solutions provide forremoval, treatment or containment of dangerous chemicals so that any remaining contaminationdoes not pose an unacceptable health risk to those who might come into contact with thecontaminants Actual or threatened releases of hazardous substances from this subsite if notaddressed by implementing the response action selected in this ROD may present a current orpotential threat to public health welfare or the environment

7 1 Summary of Human Health Risk Assessment

The baseline risk assessment estimates what risks the subsite poses if no action weretaken It provides the basis for taking action and identifies the contaminants and exposurepathways that need to be addressed by the remedial action This section of the ROD summarizesthe results of the baseline risk assessment for OU#20 of this subsite

The Nebraska Department of Health (now the Nebraska Health and Human ServicesSystem (NHHSS)) prepared a Risk Assessment in June 1994 Based upon information from thisRisk Assessment removal actions were taken at the subsite to reduce risks associated withpotential exposure to contaminants in soil and ground water In 2001 NHHSS prepared aBaseline Human Health Risk Assessment, updating the previous risk assessment by evaluatingpotential human health risks associated with exposure to ground water utilizing data collectedsince the 1994 report was published as well as updated exposure and toxicity information The2001 Baseline Human Health Risk Assessment report may be found in the AdministrativeRecord file

In general the EPA requires or undertakes remedial actions for Superfund sites when theexcess carcinogenic (cancer) risk exceeds 104 A risk of 104 represents an increase of one in tenthousand or 1/10000 for a reasonable maximum exposure (RME) This risk represents thelifetime risk of developing cancer as a result of releases from the site

Remedial actions may also be conducted at Superfund sites when the hazard index (HI)equals or exceeds one for the RME scenario The HI is a numeric expression of thenoncarcmogenic risk to human health resulting from releases from the site

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711 Identification of Contaminants of Concern

For OU#20 of the Second Street subsite the only exposure pathways which are beingevaluated are those involving exposure to ground water Dunng preparation of the 2001Baseline Human Health Risk Assessment ground water data from the numerous monitoringwells on and surrounding the subsite were analyzed It was determined that the results frommonitoring well number nine (MW 9) would be utilized to evaluate risks to human health Thiswell was selected because of its location downgradient from the FMGP source area and the factthat it is one of the most contaminated wells associated with the subsite Use of data from thiswell is most likely to ensure that the calculated risks are not underestimated and that chemicaldetections in the monitoring well can be attributed to the Second Street subsite It is possible thatsome of the contaminants of concern (COCs) have originated from the Foote Oil LUST site andbecome co-mingled with the subsite contaminants Sometimes the term chemicals of concernis used as in the 2001 Baseline Human Health Risk Assessment in place of contaminants ofconcern and the meaning is the same

Table 3 is a list of the COCs in ground water for this subsite and exposure pointconcentrations that were used for calculations of nsk When evaluating the risk associated withexposure to contaminated ground water typically a 95% Upper Confidence Limit (UCL) of thearithmetic average concentration of each COC is utilized to determine the exposure pointconcentration to ensure that the risk is not underestimated However at this subsite a straightarithmetic average concentration of each COC identified in MW 9 during 1994 through 2000sampling events was used This approach was used for several reasons (1) it is consistent withthe approach used in the 1994 nsk assessment so a more direct comparison of the results couldbe made (2) representative 95% UCLs could not be calculated for several of the chemicals dueto the limited sample size and (3) even though MW 9 is one of the most contaminated wellssampled concentrations of chemicals detected in the last round of sampling that was used for thensk assessment have decreased dramatically This approach was used to provide a reasonableand protective estimate of potential health nsks

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TABLE 3Arithmetic Average Concentration (mg/l)

MW 9 Chemicals of Concern1994 2000

Chemical of ConcernBenzeneBenzo(a)anthraceneBenzo(b)fluorantheneBenzo(k)fluorantheneBenzo(a)pyreneChryseneDibenzo(a h)anthracene1 2 DichloroethaneEthylbenzeneFluoreneIndcno(l 23 cd)pyreneNaphthalenePyreneStyreneToluene1 1 2 TnchloroethaneXylenes total

Concentration (mg/l)351000710074001900540071000200350644053500151481302062546548300383662

The COCs may be grouped into general classifications for simplification of discussionBenzo(a)anthracene benzo(b)fluoranthene benzo(k)fluoranthene benzo(a)pyrene chrysenedibenzo(a h)anthracene fluorene mdeno(l 2 3 cd)pyrene, naphthalene and pyrene are generallyreferred to as polycyclic aromatic hydrocarbons (PAHs) Benzene 1 2 dichloroethaneethylbenzene styrene toluene 1 1,2 tnchloroethane, and xylenes are generally referred to asvolatile organic compounds (VOCs)

This list of COCs is not identical to the contaminants of concern that were discussed inthe Proposed Plan There were some chemicals listed in the Proposed Plan that were identifiedin the Baseline Human Health Risk Assessment as not being directly related to this site and thuseliminated from further consideration and others that were present and site related but atconcentrations below a level of any health concern Tetrachloroethene, cis 1 2 dichloroetheneand 111 tnchloroethane were not considered COCs because they were not present in MW 9Tnchloroethene was eliminated as a COC in the Baseline Human Health Risk Assessmentbecause it was not detected in MW 9 after 1994 Acenaphthylene phenanthrene and 2-methylnaphthalene were eliminated as COCs because there are no toxicity data available for thesecompounds Acenaphthene and anthracene were eliminated as COCs because they were presentat levels below preliminary remediation goals which are used to screen out compounds duringthe risk assessment process

16

There were other chemicals specifically the PAHs except naphthalene and fluorene thatwere not included as COCs in the Proposed Plan but are in this ROD These compounds werefound in MW 9 and pose an unacceptable level of risk and thus, must be included Due todifficulties in detecting these compounds utilizing some analytical methods that have been usedin the past at this subsite there are limited data about the extent of these contaminants in theground water plume Additional sampling will be conducted during the course of the design andimplementation of this remedy to more fully determine the extent of these contaminantsHowever it is not critical to the decision making process that is being undertaken in this ROD tohave that additional data at this time

712 Exposure Assessment

Exposure scenarios are developed using current exposure pathways given existing landuses and also exposures which might reasonably be predicted based upon expected or logicalfuture land use assumptions Currently a municipal water supply is available in Hastings and acity ordinance restricts the use of ground water in the area including the subsite Therefore it isassumed that no one is currently being exposed to the contaminated ground water However,there are no measures in place that prevent the contaminated ground water plume from migratingfurther If the ground water contamination continues to be unabated the contaminated plume isexpected to expand into areas where the use may not be restricted and residents may not beprotected from exposure to contaminated ground water In the future exposure to contaminatedground water could occur through mgestion, inhalation of volatilized contaminants whileshowering and dermal exposure while bathing

713 Toxicity Assessment

The following is a discussion of the toxicity of each of the COCs in ground water

The PAHs formed during the incomplete combustion of organic substances persistthroughout the environment The PAHs are generally found in the environment as a mixture oftwo or more compounds The PAHs are essential components of coal tar and are commonlyfound at former manufactured gas plants In general, PAHs are readily bioavailable followinginhalation exposure Absorption following mgestion or dermal exposure is available and may besubject to saturation Toxic effects of PAH exposure include bone marrow depressionhepatotoxicity and immunosuppression The PAHs exhibit local dermal toxicity followingdermal exposure Both developmental and reproductive effects have been observed in animalsfollowing exposure to PAHs

Inhalation, oral and dermal exposure to PAHs have been associated with carcinogeniceffects in animals The site of tumor is influenced by the route of exposure dermal exposureinduces skin tumors respiratory tract tumors are observed following inhalation and forestomachpapillomas are observed following oral mgestion The PAHs are variable with respect togenotoxicity Benzo(a)pyrene has demonstrated genotoxic potential that requires metabolicactivation while a number of other PAHs are negative for genotoxic effects Of the 16 PAH

17

compounds which the EPA routinely analyzes samples for seven are considered to be probablehuman carcinogens or Group B2 carcinogens Those compounds are benzo(a)pyrenebenzo(a)anthracene benzo(b)fluoranthene benzo(k)fluoranthene dibenzo(a h)anthracenechrysene and mdeno(l 2,3 c d)pyrene

Benzene a contaminant of gasoline and a widely used solvent is absorbed through therespiratory and gastrointestinal tracts, and skin Benzene is commonly found at formermanufactured gas plants Benzene is considered to be a human carcinogen There is clearevidence of carcinogenic activity in rats and mice In humans a causal relationship betweenleukemia and exposure has been established by the observation of increased incidence ofleukemia in exposed workers The most predominant noncarcmogenic systemic effectsassociated with chronic exposure to benzene is hematotoxicity This toxicity is manifested as adecrease in white blood cells (leukopema) in animals In humans leukopema may progress topancytopema a decrease in all cellular elements of the blood Human benzene toxicity is oftendescribed as aplastic or hypoplastic anemia which is characterized by severe damage to the bonemarrow Direct life threatening consequences of pancytopema result from leukopema andthrombocytopema which will cause an increased susceptibility to infection or hemorrhagicconditions respectively Benzene is classified by the EPA as a Group A carcinogen which is aknown human carcinogen

Ethylbenzene is widely found in the environment as a component of coal tar andpetroleum Ethylbenzene is commonly found at former manufactured gas plants Ethylbenzeneis absorbed following inhalation ingestion or direct dermal contact with the liquid In animals,ethylbenzene exposure is associated with adverse hepatic histology without functionaldisturbance Similar histologic and enzymatic changes have been observed in the kidneysThese observations may be representative of adaptive enzyme induction rather than a toxic effectThere is not adequate information on the possibility of carcinogenic effects of ethylbenzene inanimals or humans

Toluene is an industrial solvent It is commonly found at former manufactured gasplants Toluene is rapidly absorbed following inhalation absorption following ingestion ordermal exposure is slower and more limited The predominant toxic effect following chronicexposure is impairment of the central nervous system Toluene is also considered adevelopmental toxicant following exposure of pregnant animals or humans There is notadequate information on the possibility of carcinogenic effects of toluene m animals or humans

Xylene is a man made chemical used as an industrial solvent Xylene is commonly foundat former manufactured gas plants Xylene is absorbed following ingestion and inhalation and toa much lesser extent following dermal exposure Adaptive hepatologic changes and adverserenal effects have been observed following chronic xylene exposure There is not adequateinformation on the possibility of carcinogenic effects of xylene in animals or humans

1 2 Dichloroethane and 1 1 2 tnchloroethane are both referred to as chlorinated volatileorganic compounds and are frequently used as industrial solvents 1 2 Dichloroethane is

18

classified by the EPA as a Group B2 carcinogen which is a probable human carcinogen basedupon sufficient evidence of carcmogenicity m animals but not in humans 1 1 2 Tnchloroethaneis classified by the EPA as a Group C carcinogen which is a possible human carcinogen

Table 4 lists the toxicity values and potential noncarcinogemc effects of the COCs Table5 lists the toxicity values and carcinogenic effects for the COCs

TABLE 4Noncarcinogemc Toxicity Information

Chemical

Benzene

Benzo(a)anthraceneBenzo(b)fluorantheneBenzo(k)fluorantheneBenzo(a)pyreneChryseneDibenzo(a,h)anthracene1 2 DichloroethaneEthylbenzeneFluoreneIndeno(l 2 3 cd)pyreneNaphthalenePyreneStyreneToluene1 1 2 Tnchloroethane

X>lenes total

Reference

NCEA

NANANAIRISNANANCEAIRISIRISNAIRISIRISIRISIRIS/HEASTIRIS

IRIS

RfD(mg/kg day)3 OOE 03

NANANANANANA3 OOE 021 OOE 014 OOE 02NA2 OOE 023 OOE 022 OOE 012 OOE 014 OOE 03

2 OOE+00

RfC(mg/m3)5 95E 03

NANANANANANA5 OOE 031 OOE+00NANA3 OOE 03NA1 OOE+004 OOE 01NA

7 OOE 01

Confidence

medium

NANANANANANAlowlowlowNAlow/medlowmediummediummedium

medium

Site of Action

liver

NANANANANANAliver gallbladderliver kidney/dev toxbloodNAbody wt /nasalkidneyRBCs Iner/CNSliver kidney/neurolserumchemhyper activitybody wt

RfD reference doseRfC reference concentrationNA not applicable or not availableIRIS Integrated Risk Information System (U S EPA 2001)HEAST Health Effects Assessment Standards Table (U S EPA 2001)NCEA National Center for Environmental Assessment CU S EPA 2000

19

TABLE 5Carcinogenic Toxicity Information

ChemicalBenzeneBenzo(a)anthraceneBenzo(b)fluorantheneBenzo(k)fluorantheneBenzo(a)pyreneChryseneDibenzo(a,h)anthracene1 2 DichloroethaneEthylbenzeneFluoreneIndeno(l 2 3 cd)pyreneNaphthalenePyreneStyreneToluene1 1 2 TnchloroethaneXylenes total

ReferenceIRISNCEANCEANCEAIRIS/NCEANCEANCEAIRISNANANCEANANANANAIRISNA

SF (mg/kg day) '5 50E 02730E017 3 0 E 0 17 30E 027 30E+007 30E 037 30E+009 10E 02NANA730E01NANANANA5 70E 02NA

UR (ug/m3)1

7 80E 0 68 86E 058 86E 058 86E 068 86E 048 86E 078 86E 04

NANANA

8 86E 05NANANANANANA

WOEAB2B2B2B2B2B2B2DDB2CDDDCD

Cancer Typeleukemia

skinskinskinskinskinskin

blood vesselsNANAskinNANANANAliverNA

SF slope factorUR unit risksNA not applicable or not availableIRIS Integrated Risk Information System (U S EPA2001)NCEA National Center for Environmental Assessment (U S EPA 200 1 )WOE Weieht of Evidence for CarcinocemciU fU S EPA 2001)

714 Risk Characterization

For carcinogens risks are generally expressed as the incremental probability of anindividual developing cancer over a lifetime as a result of exposure to the carcinogen Excesslifetime cancer risk is calculated from the following equation

where

Risk=CDI x SF

risk = a umtless probability (eg 2x105) of an individual developing cancerGDI = chronic daily intake averaged over 70 years (mg/kg day)SF = slope factor expressed as (mg/kg day)'

These risks are probabilities that usually are expressed in scientific notation (eg , 1x106)An excess cancer risk of 1x106 indicates that an individual experiencing the reasonablemaximum exposure estimate has a 1 in 1 000 000 chance of developing cancer as a result of siterelated exposure This is referred to as an excess lifetime cancer risk because it would be inaddition to the risks of cancer individuals face from other causes such as smoking or exposure to

20

too much sun The EPA s generally acceptable nsk range for site related exposures is 104 to106 In the NCP it is established that the 106 risk level shall be used as the point of departurefor determining remediation goals for alternatives when ARARs are not available or are notsufficiently protective because of the presence of multiple contaminants at a site or multiplepathways ofexposuref ]

In the 2001 Human Health Baseline Risk Assessment excess cancer risks were calculatedfor adults and children for the exposure scenario described in section 712 They are shown inTable 6 (Adult Carcinogenic Risks) and Table 7 (Child Carcinogenic Risks) The excess cancerrisks for an adult are 1 1x102 The excess cancer risks for a child are 7 2x103 The excesscancer risk for both an adult resident and a child resident are unacceptably high

The potential for noncarcmogenic effects is evaluated by comparing an exposure levelover a specified time period (e g lifetime) with a reference dose (RfD) derived for a similarexposure period An RfD represents a level that an individual may be exposed to that is notexpected to cause any deleterious effect The ratip of exposure to toxicity is called a hazardquotient (HQ) An HQ less than one indicates that a receptor s dose of a single contaminant isless than the RfD and that toxic noncarcmogenic effects from that chemical are unlikely TheHazard Index (HI) is generated by adding the HQs for all COCs that affect the same target organ(e g liver) or that act through the same mechanism of action within a medium or across allmedia to which a given individual may reasonably be exposed A HI less than one indicates thatbased on the sum of all HQs from different contaminants and exposure routes toxicnoncarcmogenic effects from all contaminants are unlikely A HI greater than one indicates thatsite related exposures may present a nsk to human health

The HQ is calculated as follows

Non cancer HQ = CDI/RfD

where CDI = chronic daily intakeRfD = reference dose

CDI and RfD are expressed in the same units and represent the same exposure penod

In the 2001 Human Health Baseline Risk Assessment noncarcmogenic risks werecalculated for adults and children for the exposure scenano descnbed in section 7 1 2 They areshown in Table 8 (Adult Noncarcmogenic Risks) and Table 9 (Child Noncarcmogenic Risks)The Hazard Index for an adult is 971 The Hazard Index for a child is 1 110 The Hazard Indicesfor both an adult resident and a child resident are unacceptably high

These estimates of nsk like all estimates of nsk have some degree of uncertaintyassociated with them To ensure the protection of public health, uncertainties inherent in the riskassessment process typically err on the side of conservatism therefore the nsk presented is mostoften over-estimated The selection of MW 9 as a representative well for this subsite may haveresulted in an under or over estimation of the subsite nsk Several chemicals detected in other

21

Carcinogenic Risks - Adult ResidentMW 9 Ground Water Data (1994 2000)

Arithmetic Average Concentration (mg/1)Second Street SubsiteHastings, Nebraska

tVJ

Benzene

3 510Ingestion Risk

2 37E 03Inhalation Risk

4 43E 09Dermal Risk

NA1 2 Dichloroethane

0035Ingestion Risk

3 92E 05Inhahlion Risk

NADermal Risk

NAToluene

5483Ingestion Risk

NAInhilation Risk

NADermal Risk

NA

Benzo(a)anthracene

0071Ingestion Risk

6 38E 04Inhalat ion Risk

1 03E 09Dermal Risk

1 42E 04

Ethylbenzcne

0644Ingestion Risk

NAInhalat ion Risk

NADermal Risk

NAI 1 2 Tnchloroethane

0038Ingestion Risk

2 66E 05Inhahtion Risk

NADermal Risk

NA

Benzo(b)fluoranthene

0074Ingestion Risk

6 64E 04Inhaht ion Risk

1 08E 09Dermal Risk

2 17E04Fluorene

0535Ingestion Risk

NAInhahtion Risk

NADermal Risk

NAXylenes

3662Ingestion Risk

NAInhilation Risk

NADermal Risk

NA

Uenzo(k)lluonntliene

0019Ineestion Risk

1 7 1 E 0 5Inhahtion Risk

276E 11Dermal Risk

5 57E 06Indeno(l 2,3 cd)pyrene

0015Ingestion Risk

1 35E 04Inhalat ion Risk

2 18E 10Dermal Risk

6 72E 05

Benzo(a)pyrene

0054Ingestion Risk

4 85E 03Inhala t ion Risk

7 85E 09Dermal Risk

1 58E 03Naphthilene

14813Ingestion Risk

NAInhalation Risk

NADermal Risk

NA

Chrysene

0071Ingestion Risk

638E06Inhalat ion Risk

1 03E 11Dermal Risk

1 42E 06Pvrene

0206Ingestion Risk

NAInhalation Risk

NADermal Risk

NA

Dibenzo(a h)anthraccne

0002Ingestion Risk

1 80E 04Inhalation Risk

2 9 I E 10Dermal Risk

1 30E 04Styrene

2546Ingestion Risk

NAInhilation Risk

NADerm il Risk

NA

TOTAL =

TOTAL =

TOTAL =

Ingestion Risk8 93E 03

Inhalat ion Risk1 49E 08

Dermal Risk2 I5E03

NA = not applicable or toxicit) information not availableADULT RESIDENTIAL RISK = 1 IE 02

iAUUb. 7Carcinogenic Risks - Child Resident

MW 9 Ground Water Data (1994 2000)Arithmetic A> erage Concentration (mg/1)

Second Street SubsiteHastings, Nebraska

Benzene

3 510Ingestion Risk

1 54E 03Inhalat ion Risk

444E 09Dermal Risk

NA

1 2 Dichloroethine

0035Ingestion Risk

2 54E 05Inha la t ion RiskI

NADermal Risk

NAToluene

5483Ingestion Risk

NAInliahtion Risk

NADermal Risk

NA

Benzo(a)anthracene

0071Ingestion Risk

4 HE 04Inhahtion Risk

1 03E 09Dermil Risk

8 94E 05Ethylbenzene

0644

Ingestion RiskNA

Inhalat ion RiskNA

Dermal RiskNA

112 Tnchloioethane

0038Ingestion Risk

1 73E 05Inhalation Risk

NADermal Risk

NA

Benzo(b)Duoranthene

0074Ingestion Risk

4 32E 04Inhalation Risk

1 08E 09Dermal Risk

1 37E 04Fluorene

0535Ingesdon Risk

NAInhalation Risk

NADermil Risk

NAXylenes

3662Ingestion Risk

NAInhahtion Risk

NADermal Risk

NA

Benzo(k)f luoianthene

0019Ingesdon Risk

1 11E05Inlnhtion Risk

276E 11Dermal Risk

3 52E 06Indeno(I 2 3 cd)pyrene

0015Ingestion Risk

8 75E 05Inhalation Risk

2 18E 10Dermal Risk

4 24E 05

Benzo(i)pjrenc

0054Ingestion Risk

3 15E03Inhalation Risk

7 85E 09Dermal Risk

9 99E 04Naphthalene

14813Ingestion Risk

NAInhalation Risk

NADermal Risk

NA

TOTAL =

TOTAL =

TOTAL =

Chrysene

0071Ingestion Risk

4 14E 06Inhahtion Risk

I 03E 1 1Dermal Risk

8 94E 07Pyrene

0206Ingestion Risk

NAInhalat ion Risk

NADermal Risk

NA

Ingestion Risk5 80C 03

Inhi lat ion Risk1 49E 08

Dermal Risk1 35E 03

Dibenzo(a h)anthracene

0002Ingestion Risk

1 17E 04Inlnhtion Risk

291E 10Dermal Risk

8 22E 05St) rene

2546Ingestion Risk

NAInhalation Risk

NADermal Risk

NA

NA = not applicable or toxicity information not availableCHILD RESIDENTIAL RISK = 7 2E 03

Noncarcmogenic Risks - Adult ResidentMW 9 Ground Water Data (1994 2000)

Arithmetic Average Concentration (mg/1)Second Street SubsiteHastings Nebraska

f\J-P-

-~

Benzene

3510Ingestion HQ

3592Inhala t ion HQ

9651Dermal HQ

NA1 2 Dichloroethane

0035Ingestion HQ

004Inhalation HQ

1 15Dermal HQ

NAToluene

5483Ingestion HQ

084Inhalat ion HQ

2 2 5Dermal HQ

0012

Benzo(a)anthracene

0071Ingestion HQ

NAInhalation HQ

NADermal HQ

NAEthylbenzene

0644Ingestion HQ

020Inhalation HQ

O i lDermal HQ

00041 1 2 Trichloroethaiie

0038Ingestion HQ

029Inhalat ion HQ

NADermal HQ

NA

Benzo(b)fluoranthene

0074Ingestion HQ

NAInhalation HQ

NADermal HQ

NA

Fluore ic

0535Ingeslion HQ

041Inhalat ion HQ

NADermal HQ

NAXylenes

3662Ingestion HQ

006Inhalat ion HQ

086Dermal HQ

0001

Benzo(k)fluoranthene

0019Ingestion HQ

NAInhalation HQ

NADermal HQ

NAIndeno(l 2 3 cd)pyrene

0015Ingestion HQ

NAInhalation HQ

NADermal HQ

NA

Benzo(a)pyrciie

0054Ingestion HQ

NAInhala t ion HQ

NADermal HQ

NANaphthalene

14 813Ingestion HQ

22 74Inhalat ion HQ

80780Dermal HQ

0494

TOTAL=

TOTAL =

TOTAL =

Chivsene

0071Ingestion HQ

NAInhala t ion HQ

NADerm 1 HQ

NAPyrene

0206Ingestion HQ

0^1

Inhalat ion HQNA

Dermal HQNA

INGESTION HI61 1

INHALATION HI9091

DERMAL HI05

Dibenzo(a h)anthracene

0002Ingestion HQ

NAInhala t ion HQ

NADermal HQ

NAStyrene

2546Ingestion HQ

039Inhalat ion HQ

041Dermal HQ

0007

NA = not applicable or toxicity information not availableHQ = Hazard QuotientHI = Hazard Index

ADULT RESIDENTIAL HI = 971

Noncarcmogenic Risks - Child ResidentMVV 9 Giound Witer Data (1994 2000)

Arithmetic Average Concentrition (mg/1)Second Street SubsiteHastings Nebraska

FO

Benzene

3510Ingestion HQ

11688Inhalation HQ

9651Dermal HQ

NA1 2 Dichlorocthane

0035Ingestion HQ

0 12Inhalat ion HQ

1 15Dermal HQ

NAToluene

5483Ingestion HQ

274Inhalation HQ

225Dermal HQ

0039

Benzo(a)anthracene

0071Ingestion HQ

NAInhalation HQ

NADermal HQ

NAEthylbenzene

0644Ingestion HQ

064Inhala t ion HQ

0 11Dermal HQ

0014112 Tnchloroethane

0038Ingesdon HQ

095Inhala t ion HQ

NADermal HQ

NA

Beiizo(b)fluorantlienc

0074Ingestion HQ

NAInhalation HQ

NADermal HQ

NAFluorene

0535Ingestion HQ

1 34Inhalation HQ

NADermal HQ

NA\ylencs

3662Iu0estion HQ

0 18Inhalation HQ

086Dermal HQ

0004

Uenzo(k)fluoranthcnc

0019Ingtstion HQ

NAInhala t ion HQ

NADermal HQ

NAIndeno(l 2 3 cd)pjrene

0015Ingestion HQ

NAInha la t ion HQ

NADermal HQ

NA

Benzo(a)pyrcne

0054Ingestion HQ

NAInhalat ion HQ

NADermal HQ

NANaphthalene

11813Ingestion HQ

7399Inhalat ion HQ

80780Dermal HQ

1 561

TOTAL =

TOTAL =

TOTAL =

Chrysene

0071Ingestion HQ

NAInhalat ion HQ

NADermal HQ

NAPyrene

0206Ingestion HQ

069Inhala t ion HQ

NADermal HQ

NA

INGESTION HI198 8

INHALATION HI909 1

DERMAL HI1 6

Dibenzo(a h)anthracene

0002Ingestion HQ

NAInha la t ion HQ

NADeimal HQ

NAStvrene

2546Ingestion HQ

1 27Inhala t ion HQ

041Dermal HQ

0021

NA = not applicable or toxicity information not availableHQ = Hazard Quotient

HI = Hazard IndexCHILD RESIDENTIAL HI = 1 110

monitoring wells were not evaluated for their contribution to potential subsite risk Also the useof the arithmetic average concentration rather than the highest detected concentration or the 95%upper confidence level concentration may result in an under estimation of risk for the subsite

Uncertainty in the estimates of cancer risk for this site are primarily associated with thefact that benzo(a)pyrene is the only PAH compound which has a slope factor The slope factorsutilized by the EPA for the other six carcinogenic PAHs have been assigned based on theirrelative carcinogenic potency compared to benzo(a)pyrene

The confidence in the determination of the values of the reference doses used to quantifythe noncarcmogemc risk at this subsite is rated as low to medium The noncarcmogeruc nskestimated for this subsite may be over or under estimated

7 2 Summary of Ecological Risk Assessment

The contaminated ground water at the subsite is not expected to pose any ecological nsktherefore an ecological risk assessment was not performed

7 3 Basis for Action

The response action selected in this ROD is necessary to protect the public health orwelfare or the environment from actual or threatened releases of hazardous substances into theenvironment which may present an imminent and substantial endangerment to public health orwelfare

8 0 Remediation Objectives

Remedial Action Objectives (RAOs) provide a general description of what the clean upwill accomplish These objectives are based on available information and standards such asARARs of other environmental laws and nsk based levels established in the nsk assessmentThe contaminated media present at this subsite which is being addressed by this ROD is groundwater

The RAOs for this intenm action are to prevent further migration and further worseningof the downgradient plume, to remediate or contain the contaminated ground water in order toreduce nsk and to provide a remedy which will achieve the long term objectives whencombined with a suitable remedy for the source area The long term objectives for thissubsite are (1) to reduce the contaminant levels in the ground water to levels less than the SafeDnnkmg Water Act MCLs or MCLGs if they are greater than zero and/or to state clean uplevels denved from Nebraska Title 118 regulations or to levels where the excess cancer nsk iscomputed as being less than one additional cancer per million persons of population (1 x 106) orwhere the Hazard Index is less than 1 0, so that the aquifer can be restored to its beneficial use

26

and (2) to prevent further degradation to the aquifer s ground water It is the goal of this remedyprovided it is combined with a suitable remedy for the subsite source area that the ARARs willbe met

90 Summary of Remedial Alternatives

A feasibility study (FS) was conducted to develop and evaluate remedial alternatives forground water for the subsite Remedial alternatives were initially evaluated for effectivenessimplementability and cost The alternatives meeting these criteria were further evaluated andcompared to the nine criteria required by the National Contingency Plan (NCP) In addition tothe remedial alternatives, the NCP requires that a no action alternative be considered The noaction alternative serves primarily as a point of comparison for the other alternatives Ninealternatives and two tail treatment remedies in addition to the no action alternative wereconsidered These alternatives are summarized in Table 10 The remedial alternatives forground water may be divided into two categories containment remedies and active remediesThe active remedies are intended to more rapidly remove contaminants from the ground water inan attempt to speed up the clean up

TABLE 10REMEDIAL ALTERNATIVES FOR GROUND WATER

No Action

Monitored Natural Attenuation

Containment/Pumping Treating and Discharging Ground Water and Tail Treatment Option A

Containment by In Well Aeration and Tail Treatment Option A

Containment by In Situ Bioremediation and Tail Treatment Option A

Active Remediation/Pumping Treating and Discharging Ground Water and Tail Treatment Option B

Active Remediation/In Well Aeration and Tail Treatment Option B

Active Remediation/In Situ Bioremediation

Active Remediation/In Well Aeration In Situ Bioremediation and Tail Treatment Option B

10 Active Remediation/In Situ Bioremediation and Pumping Treating and Discharging Ground Water

There are elements that are common to several of the remedial alternatives These aredescribed here so that they may be briefly referred to in the description of the appropriatealternative(s)

27

Source Area Removal Action This removal action consists of soil vapor extraction(SVE) followed by bioventing for contamination in the vadose zone of the source area andground water extraction treatment and discharge to contain the source area ground waterBioventing involves inducing air into the vadose zone to enhance the activity of the indigenousbactena While SVE removes contaminants primarily through volatilization bioventing systemspromote biodegradation of contaminants and minimize volatilization Contaminated vapors fromboth the SVE and ground water systems are thermally treated by a catalyic oxidizer Operationof this removal action began in 1997 and is on going

Downgradient Removal Action This removal action consists of an in well stripping andtreatment system located in the center of the contaminated ground water plume in the vicinity ofSecond Street and Pine Avenue Operation of this removal action began in 2001 and is on-going

Pumping, Treating, and Discharging Ground Water A component of several of theremedial alternatives considered involves extracting contaminated ground water treating it withgranular activated carbon (GAC) and discharging the treated water The ground water would bepumped to the surface through one or more extraction wells The extracted water would be pipedto a treatment system where it would pass through a GAC adsorption system that would removecontaminants to below discharge requirements Subject to a Resource Conservation andRecovery Act (RCRA) hazardous waste determination it is planned that the spent GAC wouldbe sent to the Hastings Energy Center for disposal The treated water would be piped to anexisting storm sewer that ultimately empties into Heartwell Lake in Hastings

In-Well Aeration Several of the remedial alternatives considered utilize in well aeration(IWA) technology as a component of the remedy For this technology one or more IWA wellswhich have an enlarged well casing would be used to inject air via a blower below the watertable and inside the well casing IWA treatment wells are constructed with an upper and lowerscreened section The treated ground water exits the well casing through an upper screen at thewater table In addition to stripping contaminants from the ground water the turbulenceresulting from the forced air creates an air lift effect drawing contaminated ground water into thewell casing through the lower screen The ground water flowing out and away from thetreatment well upper screen sets up a treatment zone in the aquifer The ground water within thezone would be treated several times before moving away from the treatment zone A vacuumblower applies a vacuum to the portion of the well casing above the water table removing theair/volatilized contaminant mixture This contaminated vapor would be piped to a treatmentsystem where it would be treated using vapor phase GAC Subject to a RCRA hazardous wastedetermination the spent GAC would be sent to the Hastings Energy Center for disposal

In Situ Bioremediation Some method of in situ bioremediation is a component ofseveral of the remedial alternatives considered The proposed technologies all include theintroduction of some form of slow oxygen release compound such as magnesium peroxide intothe subsurface In some cases a number of four or six inch diameter treatment wells would beinstalled in the area to be treated These wells would have large screened areas and the oxygen

28

release compound would be introduced in a sock suspended in the screened portion of thetreatment well The socks would need to be replaced periodically The spent material is nonhazardous provided a material such as magnesium peroxide is used and therefore could bedisposed of as solid waste

The oxygen release compounds could also be injected into the aquifer as a water slurryrather than the method described above The slurry would be injected via direct pushtechnologies and the injection hole would then be sealed with grout

Tail Treatment Option A The contaminated ground water plume extending east of ElmAvenue is referred to as the tail of the plume Tail Treatment Option A is one of two methodsthat have been developed to address the tail of the plume Several of the remedial alternativesincorporate one or the other of these methods to address the contamination m the tail TailTreatment Option A was referred to as Contingent Remedy A m the Feasibility Study Report andthe Proposed Plan

The first step in Tail Treatment Option A is quarterly ground water monitoring of theSW 8 well nest or another eastern monitoring well nest to be determined during the remedialdesign for a minimum of two years to determine if the contaminants in the tail have migrated Ifthe sampling confirms that the contaminants are migrating downgradient m the tail treatmentwould be implemented The treatment consists of in situ bioremediation through the injection ofoxidizer slurry as described above

An estimate of the costs associated with the full implementation Tail Treatment Option Aare as follows

Est Average Annual Operation & Maintenance (O&M) (Total/5 years) $100400/yearEstimated Total Present Worth $ 440000

It is possible that it would only be necessary to conduct the ground water monitoring after whichit may be determined that further treatment of the tail of the plume is not needed In that casethe cost would be less than the full implementation costs given above

Tail Treatment Option B For the remedial alternatives that incorporate Tail TreatmentOption B oxidizer slurry would be injected into the area comprising the tail of the plume whilethe rest of that remedial alternative was being constructed There would not be the period ofmonitoring described in Tail Treatment Option A pnor to implementation of this method ofin situ bioremediation Tail Treatment Option B was referred to as Contingent Remedy B in theFeasibility Study Report and the Proposed Plan

29

An estimate of the costs associated with Tail Treatment Option B are as follows

Initial Cost of Treatment $214,600Est Average Annual O&M (Total/2 years) $112 700/yearEstimated Total Present Worth $ 427 600

Alternative 1 No Action

The NCP requires that the EPA consider a no further action alternative against whichother remedial alternatives can be compared Under this alternative no new clean up actionwould be started and the existing removal action systems would be shut down The InstitutionalControl Area established by the city would provide near term protection for residents Over thelong term, the plume would continue to migrate and the ground water contamination wouldremain There are no capital or direct operating costs associated with this alternative However,since contaminants would be left on site a five year review of the site would be required underCERCLA and the costs associated with conducting these reviews are included m the estimatedO&M costs

Estimated Capital Cost $ 0 v

Average Est Annual O&M (Total/30 years) $ 3 100/yearEstimated Present Worth $50 200

Alternative 2 Monitored Natural Attenuation

Alternative 2 involves the use of institutional controls and ground water monitoring toaddress the potential health risks associated with the contaminated ground water Thisalternative would not involve human intervention but would rely solely on the natural aquifersystem to lower contaminant concentrations Because natural attenuation is not considered to becapable of sufficiently lowering the level of contamination to meet the RAOs this alternativewas eliminated from further consideration Therefore Alternative 2 was not carried forward forfurther evaluation and no cost estimates were prepared There is no further consideration of thisalternative in this ROD

Alternative 3 Containment by Pumping, Treating, and Discharging Ground Water andTail Treatment Option A

Alternative 3 involves pumping ground water treating with GAC and discharge toHeartwell Lake as described previously This alternative would establish a hydraulic barrier tocontrol further migration of the plume by using one or more extraction wells The extractionwells would be pumped at rates sufficient to overcome the existing ground water flow gradientThe amount of contaminated ground water removed would be the minimum amount required tocontain the migration of the plume For this alternative Tail Treatment Option A as describedpreviously would also be implemented to address the tail of the plume

30

The cost estimates for this alternative assume the two existing removal actions wouldcontinue to operate for a period often years Accordingly the annual operating costs for thisalternative are relatively high during the first ten years The following figures include the costsfor full implementation of Tail Treatment Option A

Estimated Capital Cost $ 407000Est Average Annual O&M (Total/30 years) $ 135 733/yearEstimated Total Present Worth $3,312,000

The total cost estimate for Alternative 3 that was given in the Proposed Plan did not include thecosts associated with the implementation of Tail Treatment Option A

Alternative 4 Containment by In-Well Aeration and Tail Treatment Option A

Alternative 4 involves the use of the in well aeration technology described previouslyFor this alternative it is assumed that a minimal number of in well aeration wells would beinstalled on a north south line across the downgradient edge of the plume at approximately ElmAvenue Pending the outcome of a RCRA hazardous waste determination, the spent carbonwould be sent to the Hastings Energy Center for disposal Tail Treatment Option A would beimplemented to address the tail of the plume

The cost estimates for this alternative assume the two existing removal actions wouldcontinue to operate for a period often years The annual operating costs for this alternative arerelatively high during the first ten years The following figures include the costs for fullimplementation of Tail Treatment Option A

Estimated Capital Cost $ 600,000Est Average Annual O&M (Total/30 years) $ 161,533/yearEstimated Present Total Worth $3 975 000

The total cost estimate for Alternative 4 that was given m the Proposed Plan did not include thecosts associated with the implementation of Tail Treatment Option A

Alternative 5 Containment by In Situ Bioremediation and Tail Treatment Option A

Alternative 5 involves the use of one of the methods of in situ bioremediation describedpreviously The specific method to be utilized in this alternative includes the installation of twolines of treatment wells with the oxygen release compound being suspended in the screenedportion of the wells m a sock Over a penod of several months the oxygen release compoundwould dissolve releasing oxygen into the ground water and then the socks would be replaced Itis assumed that the two lines of treatment wells would span the plume of contaminated groundwater in the vicinity of Cedar Avenue and Elm Avenue Tail Treatment Option A would beimplemented to address the tail of the plume

31

The cost estimates for this alternative assume the two existing removal actions wouldcontinue to operate for a penod often years The following figures include the costs for fullimplementation of Tail Treatment Option A

Estimated Capital Cost $ 683 000Est Average Annual O&M (Total/30 years) $ 210267/yearEstimated Present Worth $4 881,000

The total cost estimate for Alternative 5 that was given in the Proposed Plan did not include thecosts associated with the implementation of Tail Treatment Option A

Alternative 6 Active Remediation by Pumping, Treating, and Discharging Ground Waterand Tail Treatment Option B

Alternative 6 is similar to Alternative 3 but involves more aggressive pumping intendedto speed up the subsite remediation process by increasing the rate of extraction of thecontaminated ground water This alternative includes the use of extraction wells, treatment ofcontaminated ground water by GAC adsorption, and discharge of the treated ground water toHeartwell Lake For this alternative the proposed extraction wells would be pumping at rateshigh enough to capture the entire north south extent of the plume within the cones of depressioncreated by the wells The treatment system associated piping and housing would be similar tothat needed for Alternative 3 however because the flow rate through the system would begreater all of the equipment would be scaled up in size appropriately Once again subject to aRCRA hazardous waste determination the assumption is that the spent carbon from thetreatment system would be sent to the Hastings Energy Center for disposal and the treated waterwould be disposed into Heartwell Lake Tail Treatment Option B as described previously wouldbe used to address the tail of the plume

The cost estimates for this alternative assume the two existing removal actions wouldcontinue to operate for a penod of thirty years These costs include the cost of implementingTail Treatment Option B

Estimated Capital Cost $ 898000Estimated Average Annual O&M (Total/30 years) $ 217467/yearEstimated Present Worth $5,849 000

Alternative 7 Active Remediation by In-Well Aeration and Tail Treatment Option B

Alternative 7 is similar to Alternative 4 but would be a more aggressive approach toremediate the ground water using in well aeration For this alternative several in well aerationwells would be installed The number of wells needed would be determined during the remedialdesign but more wells would be needed than for the containment remedy in Alternative 4 Inwell aeration wells would remove the contaminants from the ground water and GAC would treatthe contaminated vapor, as in Alternative 4 Subject to a RCRA hazardous waste determination

32

the spent GAC would be transported to the Hastings Energy Center for disposal Tail TreatmentOption B as described previously would be used to address the tail of the plume

The cost estimates for this alternative assume the two existing removal actions wouldcontinue to operate for a period of thirty years These costs include the cost of implementingTail Treatment Option B

Estimated Capital Cost $1 369 000Estimated Average Annual O&M (Total/30 years) $ 234 367/yearEstimated Present Worth $5 849 000

Alternative 8 Active Remediation by In Situ Bioremediation

Alternative 8 would use in situ bioremediation to remediate the contaminated groundwater in the plume For this alternative the oxygen release compounds would be injected intothe aquifer as a water slurry as described previously While the use of wells to deliver theoxygen to the ground water as proposed for Alternative 5 is feasible direct injection is proposedfor this alternative as it may more quickly clean up the ground water than the use of wells andmay be better suited for aggressively treating the extensive area to be remediated The tail of theplume would be treated in the same manner Therefore, neither of the tail treatment remedieswould be implemented

The cost estimate for this alternative assumes that the two existing removal actions wouldcontinue to operate for a period of thirty years

Estimated Capital Cost $ 600000Estimated Average Annual O&M (Total/30 years) $ 242 833/yearEstimated Present Worth $5 440,000

Alternative 9 Active Remediation by In-Well Aeration, In Situ Bioremediation, and TailTreatment Option B

Alternative 9 would use a combination of in-well aeration and in situ bioremediation toaddress the contaminated ground water plume Similar to Alternative 4 a minimal number of inwell aeration wells would be installed to move the contaminants from the ground water to thevapor phase and vapor phase GAC would treat the contaminated vapor

The second component of Alternative 9 in situ bioremediation would be implementedsimilar to Alternative 5 with a north south line of wells to span the entire width of the plumeAs described previously socks containing slow release oxidizer would be suspended in thewells Tail Treatment Option B would be implemented to address the tail of the plume The twoexisting removal actions would continue to operate for a period of thirty years

33

The estimated costs for Alternative 9 including the costs for Tail Treatment Option Bare as follows

Estimated Capital Cost $1 277 000Estimated Average Annual O&M (Total/3Oyears) $ 239 733/yearEstimated Present Worth $5,898 000

7T

Alternative 10 Active Remediation by In Situ Bioremediation and Pumping, Treating,and Discharging Ground Water

Alternative 10 would use a combination of two technologies to achieve the remedialaction goals for the subsite in the most aggressive manner possible The two technologies are insitu bioremediation and ground water extraction and treatment with GAC followed by dischargeto Heartwell Lake There is no need to include a separate tail remedy since treatment of thetail of the plume is included as part of this alternative

Alternative 10 as described m the FS Report included the following two components (1)in situ bioremediation that would be done by installing two lines of treatment wells where a slowrelease oxygen compound would be introduced to the aquifer in a sock to enhancebiodegradation of the contaminants and an extraction well that would capture the contaminatedground water at the leading edge of the plume to prevent further migration The extraction welltreatment system associated piping and housing would be similar to that described previously

Prior to preparation of the Proposed Plan it was determined that a modification to thisalternative as it was described in the FS Report would be more effective and slightly lessexpensive For the reconfigured Alternative 10 the pump and treat system will be locatedupgradient while the bioremediation area will be located downgradient and will cover a largerarea The advantage of this approach is that by locating the permanent pump and treat system ma more central location nearer the most heavy contamination the system is likely to be moreeffective for a longer period of time Another improvement included in reconfiguredAlternative 10 is that it may utilize a combination of fixed biotreatment wells with the oxygenrelease compound m a sock and injection of the oxygen release compounds as a water slurryvia direct push technology This version of Alternative 10 is described in more detail in thedocument entitled Reconfigured Alternative 10 Costs which may be found in theAdministrative Record and is what will be referred to as Alternative 10 throughout theremainder of this ROD

For the alternative it is assumed that the two existing removal actions would continue tooperate for a period of thirty years The cost estimates for Alternative 10 are as follows

Estimated Capital Cost $1 571 000Estimated Average Annual O&M (Total/30 years) $ 249 157/yearEstimated Present Worth $6 475 000

34

10 0 Summary of Comparative Analysis of Alternatives

Nine criteria are used to evaluate the different remediation alternatives individually andagainst each other in order to select a remedy The nine evaluation criteria are (1) overallprotection of human health and the environment (2) compliance with ARARs (3) long-termeffectiveness and permanence (4) reduction of toxicity, mobility, or volume of contaminantsthrough treatment, (5) short term effectiveness (6) implementability (7) cost (8) state/supportagency acceptance and (9) community acceptance This section of the ROD profiles the relativeperformance of each alternative against the nine criteria noting how it compares to the otheroptions under consideration The nine evaluation criteria are discussed below

101 Overall Protection of Human Health and the Environment

Overall protection of human health and the environment addresses whether eachalternative provides adequate protection of human health and the environment and descnbes howrisks posed through each exposure pathway are eliminated reduced or controlled throughinstitutional controls, engineering controls and/or treatment

Alternatives 3 through 10 could provide adequate protection of human health and theenvironment by eliminating reducing or controlling risk through varying levels of treatment

Alternatives 6 and 10 provide the highest level of protectiveness when compared to theother alternatives These two alternatives have the greatest potential to eliminate risk This rankassignment is based on the known effectiveness of pump and treat technology when contrastedwith varying levels of uncertainty inherent with newer technologies being proposed forAlternatives 4 5 7 8 and 9 The effectiveness of a ground water extraction well in capturingthe contaminant plume is easy to verify The capability of the other two innovative technologies(in well aeration and in situ biodegradation) is best described as reducing or controlling risk Inaddition verification of the effectiveness of these technologies is more difficult The certainty ofplume capture and the known efficiency of the proposed GAC treatment process creates thehighest level of reliability for Alternatives 6 and 10 when compared to Alternatives 3 4 5 7, 8and 9

Alternatives 4 and 5 employ technologies which are expected to have lower overallremoval efficiencies Therefore they would rely on the ability of Tail Treatment Option A toprovide an additional level of protectiveness Because Tail Treatment Option A would employin situ bioremediation there remains some questions about protectiveness for these alternativesAlternatives 4 and 5 aie ranked below Alternatives 378 and 9 because there are someremaining site specific concerns about well fouling for the in well aeration technology Wellfouling results in system down time

Alternative 1 provides no additional protection for human health and the environment

35

As described above with regard to overall protection of human health and theenvironment the alternatives rank in the following order from least protective to mostprotective

Overall Protectiveness

Least Protective ^ Most Protective

1 45 3 7 8 9 6 10

Because Alternative 1 is not protective of human health and the environment it iseliminated from further consideration

10 2 Compliance with ARARs

Section 121(d) of CERCLA requires that remedial actions at CERCLA sites at least attainlegally applicable or relevant and appropriate federal and state requirements standards cntenaand limitations which are collectively referred to as ARARs unless such ARARs are waivedunder CERCLA Section 121(d)(4) Because the remedial action being selected in this Record ofDecision will be an interim action it need not achieve ARARs all by itself since it is onlypart of a total remedial action that will attain such level or standard of control when it iscompleted in the language of Section 121(d)(4)(A) of CERCLA 42 U S C § 9621(d)(4)(A)However, a longer term goal of this remedy is to achieve ARARs if the remedy in this OU #20ROD can be combined with a suitable remedy for the source area (OU #12)

Applicable requirements are those substantive environmental protection requirementscntena or limitations promulgated under federal or state law that specifically address hazardoussubstances the remedial action to be implemented at the site the location of the site or othercircumstances present at the site Relevant and appropnate requirements are those substantiveenvironmental protection requirements criteria or limitations promulgated under federal or statelaw which while not applicable to the hazardous matenals found at the site the remedial actionitself the site location or other circumstances at the site nevertheless address problems orsituations sufficiently similar to those encountered at the site that their use is well suited to thesite

There are three types of ARARs chemical specific location specific, and actionspecific Chemical specific ARARs may determine cleanup levels for specific chemicals ordischarge limits Action specific ARARs establish controls or restrictions on the remedialactivities that are part of the remedial solution Action specific ARARs are tnggered by thespecific remedial activity rather than the contaminants present Location specific ARARs setlimitations on remedial activities as a result of the site s location or charactenstlcs (such as beinglocated m a flood plain) Also considered at the time ARARs are established are policiesguidance and other sources of information which, though not enforceable, are to be considered

36

in the selection of the remedy and the implementation of the ROD These to be consideredstandards may provide additional important benchmarks that can be considered in selecting aremedy

The following chemical specific ARARs were used to establish the clean up levels forground water as part of this remedy

Federal Safe Drinking Water Act and Nebraska Title 118 standards Under theNational Contingency Plan, 40 C F R 300 430(e)(2)(i)(B) federal Safe Drinking Water Act(SDWA) standards which are applicable at the tap are relevant and appropriate to a clean up ofground water which is a current or potential source of drinking water The SDWA s maximumcontaminant level (MCL) is used for any contaminant whose maximum contaminant level goal(MCLG) is zero otherwise the MCLG is used The substantive requirements of Nebraska s Title118 regulations are also applicable to this remedy including narrative and numericalrequirements (which are also called maximum contaminant levels or MCLs) and the groundwater classifications and clean up standards set forth in or derived from Title 118s AppendixA Table 12 provides the ground water clean up levels which have been derived for this cleanup either from numerical federal and/or state MCLs or using the other levels such as EPA healthadvisory levels established consistent with Title 118, Appendix A Step 8

The following action specific or location specific ARARs and/or other environmentaland safety laws and regulations are relevant to all of the alternatives evaluated except for theno action alternative and would need to be complied with as the remedy is carried out

Clean Water Act Surface discharges of treated water would need to comply with thesubstantive requirements of the federal National Pollutant Discharge Elimination System(NPDES) regulations and Nebraska Title 119 and 121 and discharge limits would need to be setfor specific contaminants found at the subsite in order to ensure that federal and state waterquality requirements will be met As provided in CERCLA Section 121(e)(l) a permit is notneeded as long as the discharge point is located on site

Air regulations Nebraska Title 129 regulations would require carbon adsorptiontreatment if more than 2 5 tons per year of any one hazardous air pollutant would be dischargedto ambient air or if more than ten tons per year would be discharged of any combination ofhazardous air pollutants In accordance with CERCLA Section 121(e)(l), a permit is not neededif the location of the discharge to ambient air is on site In accordance with state and federal lawsteps will also need to be taken to suppress dust emissions during any construction

Hazardous waste Regulations under the federal Resource Conservation and RecoveryAct (RCRA) and Title 128 regulations will need to be followed to determine if solid wastesexcavated created through treatment or otherwise generated during the implementation of theremedy are hazardous If any hazardous wastes are stored treated or disposed of on site thesubstantive requirements of these regulations will be applicable or relevant and appropriate Allgenerators of solid wastes are required by 40 CFR 262 11 to do a waste determination in order to

37

determine if a given waste is hazardous Wastes determined to be hazardous if kept on site needto be managed in accordance with the substantive requirements of RCRA and Title 128 If anywastes are shipped off site such off site disposal will need to be done in accordance with allapplicable environmental laws including RCRA and on site accumulation times will also belimited by RCRA As provided in Section 121(d)(3) of CERCLA any off site shipment shippedto a hazardous waste disposal facility must be shipped to a facility that is in compliance withSection 3004 and 3005 of the Solid Waste Disposal Act

Locations of wells on file with Natural Resources District and Department ofNatural Resources The substantive requirements of R S Neb 46 602(1) are applicable orrelevant and appropriate EPA will provide the location of its wells to the Department of NaturalResources and the Natural Resources District (NRD) to ensure for the duration of the projectthat other wells which might interfere with clean up or monitoring will not be drilled near theEPA s wells The EPA does not require an actual permit from the NRD or from a state agencyfor placement or operation of monitoring or treatment wells on site or for the withdrawal ofwater However the EPA will cooperate with state agencies and the NRD when carrying outclean up activities and will make available the ground water information collected during theclean up

Water Well Standards and Contractor Licensing Act The substantive standards ofTitle 178 are applicable as are standards aimed at ensuring those engaged in well drilling andwell construction are qualified

Other requirements Any action taken at the subsite will also need to comply with lawsand regulations governing construction in a flood plain, if applicable and occupational safetyand health historic preservation and protection of endangered species

Compliance with ARARs addresses whether a remedy will meet all of the applicable orrelevant and appropriate requirements of other federal and state environmental statutes orprovides a basis for invoking a waiver Alternatives 3 through 10 would all ultimately meet theclean up standards in Table 12 provided that each is combined with a suitable source arearemedy On the other hand Alternatives 1 and 2 would not meet these standards

103 Long-term Effectiveness and Permanence

Long term effectiveness and permanence refers to expected residual risk and the abilityof a remedy to maintain reliable protection of human health and the environment over time onceclean up levels have been met This criterion includes the consideration of residual risk that willremain on site following remediation and the adequacy and reliability of controls

Alternatives 6 9 and 10 are likely to provide the best performance for this criteriaAlternative 6 is designed to capture and treat the area of the plume between Pine and ElmAvenues For Alternatives 6 and 9 the area east of Elm would be treated by Tail TreatmentOption B Alternatives 9 and 10 are nearly equivalent to 6 because both Alternatives 9 and 10utilize a combination of technologies thereby decreasing the chance of remedy failure

38

Alternatives 3 7 and 8 are less effective in the long term than Alternatives 6 9 and 10Alternative 3 is included with the more aggressive Alternatives 7 and 8 because pump and treatcombined with GAC has the ability to achieve greater overall contaminant removal efficiency forthe broad range of contaminants of concern present in the ground water GAC will moreeffectively remove the less volatile compounds and higher molecular weight compounds than inwell aeration or in situ bioremediation technologies

Alternatives 4 and 5 would provide an acceptable level of long term effectiveness andpermanence but are not intended to be as aggressive as the more active alternatives and mayhave lower overall removal efficiencies (

In terms of long term effectiveness the alternatives rank m the following order fromleast effective to most effective

Long Term Effectiveness and Permanence

Least Effective ^ Most Effective

4 5 3 7 8 6 9 1 0

Reviews at least every five years as required would be necessary to evaluate theeffectiveness of all of these alternatives as long as hazardous substances remain on site inconcentrations above health based levels

10 4 Reduction of Toxicity, Mobility, or Volume of Contaminants ThroughTreatment

Reduction of toxicity mobility or volume through treatment refers to the anticipatedperformance of the treatment technologies that may be included as part of a remedy

All of the alternatives are designed to control migration of contaminants in the aquiferGround water pumping which is a key component of Alternatives 3 6 and 10 is considered tobe the most reliable means to prevent any further migration of the contaminant plume

Alternatives 6 7 8 9 and 10 would provide the greatest reduction of the volume ofcontaminants through treatment The most effective treatment technology is extraction withGAC which is a component of Alternatives 3 6 and 10 Alternative 3 has limited effectivenessdue to a lower pumping rate The greatest reduction in toxicity can be achieved through the useof GAC

In terms of reduction of toxicity, mobility or volume of contaminants the alternativesrank in the following order from least effective to most effective

Reduction of Toxicity, Mobility, or Volume

Least Effective •* Most Effective

3 4 5 7 8 9 6 1 0

39

105 Short-Term Effectiveness

Short term effectiveness addresses the period of time needed to implement the remedyand any adverse impacts that may be posed to workers, the environment, and the communityduring construction and operation of the remedy until clean up goals are achieved

The effectiveness of Alternatives 3 and 4 can be verified within a five year timeframeAlternative 3 has the advantage of being the easiest to implement and verify plume capture andcontaminant removal effectiveness The data needed to demonstrate that the remedy isfunctioning as intended can be collected soon after startup of the treatment system

Workers and residents can be protected during implementation of all the alternativeshowever, as a general rule the amount of intrusive work increases the potential that injury couldoccur due to either accident or carelessness Alternative 3 can be implemented in the shortestamount of time, requires the least amount of aquifer intrusive work and involves relativelycommon equipment and procedures Because Alternative 4 does not require construction of apipeline it has approximately the same short term effectiveness as Alternative 3

For the other alternatives the general level of activity at the subsite would slightlyincrease the short term risks The active alternatives pose slightly more risk because moreconstruction activities are required Alternative 8 requires the greatest level of intrusive workAlternatives 9 and 10 involve multiple remedial technologies and require more extensiveconstruction activities Each of the alternatives would be implemented to minimize any potentialincrease in nsk presented by drilling activities ground water sampling extraction and treatmentoperations Personal protective equipment and other health and safety measures would beimplemented as needed to protect workers from such hazards

Considering a balance of the number of years to achieve goals scope of intrusiveconstruction work required and complexity of construction activities the alternatives rank in thefollowing order from least effective to most effective It should be noted that the differencebetween the least and most effective alternatives in the short term is not great

8 9 10

Short Term

Least Effective •

1 5

Effectiveness

* Most Effective

6 7 3 4

10 6 Implementabihty

Implementabihty addresses the technical and administrative feasibility of a remedy fromdesign through construction and operation Factors such as availability of services and materialsadministrative feasibility, and coordination with other governmental entities are also considered

40

All of the alternatives may be both technically and administratively implementableTechnical implementability is more easily assessed based on the level of difficulty andanticipated scope of remedial activities Alternatives 3 and 4 are the most easily implementedImplementation of Alternative 4 is more technically uncertain due to the limited experience within well aeration technology for hydrocarbon remediation within the local aquifer There havebeen problems with the downgradient removal system located near Pine Avenue due to foulingof the wells This problem is believed to be due to the buildup of naturally occumng carbonateprecipitate on the well screens Alternative 3 may have slightly more administrative uncertaintydue to the need for access to build the pipeline needed to carry the treated water to the stormsewer

All technologies associated with the alternatives are available and generally proven Bothtechnical and administrative uncertainty increase with Alternatives 6 789 and 10 Thesealternatives are more intrusive and require access to more properties The in situ technologiesintroduce added uncertainty due to technical problems which can interfere with optimalperformance For the reasons stated above Alternatives 5, 6 and 7 are moderately difficult toimplement

The property access requirements for Alternative 8 make administrative implementabilitya major issue for this alternative Alternatives 9 and 10 are the most difficult to implementbecause they involve multiple technologies

In terms of implementability the alternatives rank in the following order from leastdifficult to most difficult to implement

Implementability

Least Difficult •* Most Difficult

3 4 5 6 7 8 9 1 0

107 Cost

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

Table 11 presents the capital and O&M costs for all alternatives based on an assumedproject life of 30 years The present worth cost represents the equivalent value in 2003 dollars ofthe corresponding remedy The Total Present Worth estimates in Table 11 include O&M costsdiscounted to the current year plus the capital costs

41

TABLE 11SUMMARY OF COST ESTIMATES

AlternativeNumber

1

3

4

5

6

7

8

9

10

Capital Cost

$0

$407 000

$600 000

$683 000

$898 000

$1369000

$600 000

$1277000

$1 571 000

Average Annual O&MCosts

$3 100

$135733

$161 533

$210267

$217467

$234 367

$242 833

$239 733

$249 157

Total PresentWorth

$50 200

$3312000

$3 975 000

$4881000

$4 992 000

$5 849 000

$5 440 000

$5 898 000

$6 475 000

NotesFor cost comparison project durations have been standardized to 30 yearsAverage Annual O&.M Costs are calculated by dividing Total O&M by 30 yearsAll present worth costs assume a 3 9% annual discount rate

Capital costs are up front expenditures that are incurred during the construction phase ofthe project The capital costs include engineering construction and equipment costs The O&Mcosts are presented in Table 11 as an average annual cost over the assumed 30 year project lifeAs a basis for comparison of alternatives having costs spread over a number of years the totalproject present worth cost was calculated to provide a measure of comparison in constant dollars

Alternatives 3 4 and 5 are less costly both in terms of the capital costs and total presentworth However since these alternatives are designed to only contain the contamination it islikely that they will need to be operated for significantly longer than the 30 years that wereassumed in the cost estimate Alternative 10 would be more likely to achieve the clean up goalsmore quickly

The cost estimating assumptions for each of the alternatives are included in the FSReport

With the exception of Alternative 10 these cost figures are somewhat different than thosepresented in the Proposed Plan since those cost figures were based on an earlier version of the FSReport However even though most of the costs increased each of the alternatives remained inthe same rank order from least to most expensive A change that was made from the Proposed

42

Plan in the presentation of the cost information in this ROD is that Alternatives 3 4 and 5include the costs associated with the implementation of Tail Treatment Option A m theirrespective costs

108 State/Support Agency Acceptance

The NDEQ has participated in the remedial investigation and the feasibility study for theSecond Street subsite including review of the RI and FS Reports The NDEQ has expressed itssupport for Alternative 10 The state also urges that additional action be conducted to addressthe source area (OU #12)

10 9 Community Acceptance

Written and oral comments were received during the public meeting expressing the viewthat if the city of Hastings is to bear any financial responsibility for implementing the SelectedRemedy it is their preference that no action be taken However if there were assurances that thecity would have no financial responsibility for implementing the remedy, some commentorswould not be opposed to the Selected Remedy The EPA provides a response to the comments inthe Responsiveness Summary section of this ROD

11 0 Principal Threat Wastes

The NCP establishes an expectation that the EPA will use treatment to address theprincipal threats posed by a site wherever practicable (NCP §300 430(a)(l)(m)(A)) In generalprincipal threat wastes are those source materials considered to be highly toxic or highly mobilewhich generally cannot be contained in a reliable manner or would present a significant risk tohuman health or the environment should exposure occur

This ROD does not address the source area and therefore is not aimed specifically atthose wastes most likely to be principal threat wastes There is a possibility that contaminantsexist in the ground water as dense nonaqueous phase liquids (DNAPLs), which may also beconsidered principal threat wastes although no areas of DNAPL have been identified None ofthe alternatives include actions specifically designed to address DNAPL

12 0 Selected Remedy

The Selected Remedy for cleaning up OU #20 of the Second Street subsite is Alternative10 Alternative 10 provides for in situ bioremediation and pumping treating, and dischargingground water

43

121 Summary of the Rationale for the Selected Remedy

The Selected Remedy was chosen over other alternatives because it is expected to achievesubstantial reduction of the risks posed by contaminated ground water in the least amount oftime Although Alternatives 3 4 and 5 would contain the ground water contamination it islikely that they would not remove all of the contamination within the 30 year timeframe and mayhave to continue to operate for a substantially longer period of time It is possible that due to theaggressive approach for the Selected Remedy that the clean up of the ground water may takefewer than the 30 years assumed in the cost estimate Although Alternatives 678 and 9 areintended to actively clean up all of the contamination, rather than simply contain it they aregenerally less effective and less protective The Selected Remedy is cost effective even thoughthe cost is higher than the other alternatives since it is expected to achieve the RAOs in less timeThe Selected Remedy satisfies the preference for treatment

122 Description of the Selected Remedy

The Selected Remedy combines both enhanced bioremediation through the addition ofoxygen release compound to the aquifer with conventional ground water extraction and treatmentwith GAC The pump and treat system will be located in a central location near the most heavycontamination where it is likely to be effective for a significant period of time while thebioremediation area will be located further downgradient in the plume and may cover a largearea The Selected Remedy may utilize a combination of fixed biotreatment wells with theoxygen release compound in a sock and injection of the oxygen release compounds as a waterslurry via direct push technology The details of the design and implementation of the remedywill be determined during the remedial design To summarize the mam elements of the SelectedRemedy are the following

Extraction of ground water combined with treatment by GAC,

In situ biotreatment adding oxygen release compounds to the aquifer

Continued operation of the source area pump and treat and SVE systems

Continued operation of the Pine Avenue in well aeration treatment system and

Long term ground water monitoring wells will be placed as needed to monitor theeffectiveness of the treatment systems

As noted above the source area pump and treat system and SVE system and thedowngradient in well aeration system which are currently operated as Superfund removalactions, are a part of the Selected Remedy

44

A combination of these systems will continue to operate until the remedial goals areachieved As discussed above it is anticipated that this remedy will not be able to achieve thelong term remedial goals on its own but that it could do so if combined with a suitable remedyaddressing the source area and assuming the Foote Oil LUST site is addressed This isparticularly true for the western end of the plume which will persist until the source areacontamination is addressed The Selected Remedy does provide a good opportunity to greatlyreduce and potentially eliminate the eastern plume within the 30 year time frame

EXISTING SOURCE AREAPUMP AND TREAT SYSTEM

BURLINGTON NORTHtRN

PUMP AND TREATWITH GACEXISTING PINE AVE

IWA SYSTEMFIGURE 4CONCEPTUAL DIAGRAMOF SLECTED REMEDYSECOND STREET DOWNGRADIENT PLUME

As part of the design process for the Selected Remedy the design and performance of theexisting removal systems will be reviewed and changes or improvements that may be needed willbe made At this point there are known problems with fouling by oil tar and precipitates thatneed to be addressed A conceptual diagram of the Selected Remedy is shown in Figure 4

Table 12 lists the ground water clean up levels for this action for each of the contaminantsof concern except for 1 2 dichloroethane Although 1 2 dichloroethane was identified as a COCit appears to be associated only with petroleum contamination, not with the FMGP propertyCERCLA has an exclusion with respect to addressing petroleum or gasoline contamination Thestate s LUST program addresses contamination at petroleum facilities Therefore the actiondescribed in this ROD will not address the petroleum source and will address the Foote Oilcontamination only incidentally that is to the extent that it is already commingled with thecontaminated ground water plume emanating from the FMGP property The federal SafeDrinking Water Act (SDWA) and Nebraska s Title 118 regulations are ARARs for this subsiteThe federal and state MCLs and the federal non zero MCLGs are the clean up levels for thosecompounds that have these regulatory values Consistent with Nebraska Title 118 Appendix A

45

Step 8 for COCs that have no MCLs first it is determined if there is a preliminary clean uplevel such as a Lifetime Health Advisory Level (HAL) if there are no regulatory clean uplevels the clean up level is to be set at the 106 cancer nsk or the concentration of thecontaminant that is associated with a given level of cancer nsk or the concentration equivalent toa hazard quotient of one or at the laboratory detection limit (if higher and within an acceptablerange) There are MCLs or non zero MCLGs for benzene ethylbenzene toluene xylenesstyrene 1 1 2 tnchloroethane and benzo(a)pyrene There is no MCL for naphthalene but there isa HAL The Nebraska Health and Human Services System has determined the concentration ofeach of the carcinogenic PAHs at the 106 cancer nsk or the concentrations equivalent to a hazardquotient of one However it is not possible at the present tune to detect some of thesecompounds at the low concentrations associated with these nsk levels Therefore the clean uplevels in Table 12 for benzo(a)anthracene benzo(b)fluoranthene dibenzo(a h)anthracene andmdeno(l 2 3 cd)pyrene are at the concentrations that can be detected in a ground water sampleusing available analytical methods and represent a cancer nsk range of approximately 1x104 to5xl05

46

TABLE 12Ground Water Clean Up Levels

Second Street Subsite OU #20 in ug/1

ContaminantBenzene

Benzo(a)anthracene

Benzo(b)fluorantheneBenzo(k)Floranthene

Benzo(a)pyrene

Chrysene

Dibenzo(a h)anthracene

Ethylbenzene

FluoreneIndeno(l 2 3 cd)pyrene

Naphthalene

Pyrene

Styrene

Toluene

1 1 2 Trichloroethane

Xylenes total

Clean Up Level (jig/I)5001

0102024 0

0 1

700

1300

0 1

100

450

100

1000

30

10000

MCL

Detection Limit

Detection Limit

Health based

MCL

Health based

Detection Limit

MCL

Health based

Detection Limit

HAL

Health based

MCL

MCL

MCLG

MCL

ug/1 micrograms per literMCL federal and state Maximum Contaminant Level (SDWA and Title 1 1 8)MCLG federal Maximum Contaminant Level Goal (SDWA)HAL Lifetime Health Advisory Level (EPA)Health based 1 0 6 cancer risk or HI<1 0

Additional ground water sampling will be conducted during the remedial designto get a more thorough understanding of the extent of contamination throughout thecontaminated ground water plume

123 Summary of the Estimated Remedy Costs

Table 13 is taken from the FS Report and provides a detailed cost estimate forimplementation of the Selected Remedy The discount rate used in calculation of the present networth costs was 3 9 percent The capital costs are $1 571 000 the average O&M costs are$249 157 and the present net worth is $6 475 000 The information in this cost estimatesummary table is based on the best available information regarding the anticipated scope of theremedial alternative Changes in the cost elements are likely to occur as a result of new

47

TABLE 13Present Worth Cost Estimate

Reconfigured Alternative 10 Active Remediation/Groundwater Extraction andTreatment and In Situ Bioremediation

Cost Estimate Component Quantity Units Unit Cost | Capital Cost | Annual CostCAPITAL COSTSDirect Push Sampling to Determine Depth/Location ofthe Extraction Well and In Situ Biotreatment Wells (SixSampling Probes at Each of Two Locations)Extraction Well (1 8 PVC well to a depth of 1 70 feetdevelopment well pump installation and well vault)Submersible Pump (support wire flow and controldevices electric service to wellhead)Groundwate Collection Piping (includes PVC pipingbedding and trenchmg)(No Double Contained)Prefabricated Structure (30x20 slab on grade)Purchased Package (GAC Vessels Control PanelEffluent Storage Tank, Discharge Pump)Other Direct Costs fo Packaged S>stemDischarge Piping to Hearrwell Lake la UP StormSewer (includes PVC p ping bedding and trenching)In Situ Bioremedialion (17 6 wells 30 screens acrossmost contaminated zone of Plume uells to be up to 185feet deep)In Situ Bioremediation Sock Canisters (6 per well)Plume Tail Treatability Study (Preparation of planscontracting, installation of a line of eight chemicalinjection points and three direct push sampling pointsAt four six and eight months direct push andmonitoring well sampling of the injection area )Monitoring Wells (1 nest of three 2 PVC wellsinstalled to depths of 145 185 and 225 feet)

1

170

1

80

11

11 700

17

1021

555

LS

VLJ

EA

LF

EALS

LSLF

Well

EachLS

VLF

$48 800

$200

$5900

$47

$40 200$44 300

$6200$42

$19500

$150$350000

$39

DIRECT CAPITAL COST SUBTOTALBid Contingency (157)Scope Contingency (157)

TOTAL DIRECT CAPITAL COSTPermitting and Legal (5/)Construction Services (10/)

CONSTRUCTION COSTS TOTALEngineering Design (8/)

TOTAL CAPITAL COST

$48 800

$34 000

$5900

$3800

$40 200$44 300

$6200$71 400

$j31 500

$15300$350000

$21 600

$973,000$146000$146000

$1265000$63 300

$126500$1,454,800

$116400$1,571,000

R configured Alternative 10

September 26 2002Second Street Downgrad ent Plume

0461120112

48

TABLE 13 (Continued)Present Worth Cost Estimate

Reconfigured Alternative 10 Active Remediation/Groundwater Extraction andTreatment and In Situ Bioremediation

Cost Estimate Component | Quantity | Units Unit Cost I Capital Cost | Annual CostANNUAL O&M COSTSUTILITY COSTS

YEARS 1 30 (Phases 1 2 and 3)Source Area Remo\al ActionPine Avenue Removal Action

1212

MoMo

$1 550SI 030

$18600$12400

YEARS 1 through 10 (Phase 1)Downgradient Extract Well ElectricDowngradient Extract Well Natural Gas

143 80012

KWh/YRMo

$005$7700

$7200S900

SPENT CARBON REPLACEMENT COSTSYEARS 1 30 (Phases I 2 and 3)Source Area Removal ActionPine Avenue Removal Action

42

YRYR

$9,700$9,900

$j8 800$19,800

YEARS 1 !0(Phas 1)Downgradient Extract Well 1 YR $4100 $4 100

OPERATOR REQUIREMENTYEARS 1 30 (Phases 1 2 and 3)Source Area Removal Action (4 hours/workingday)Pine A\enue Removal Action (4 hours/week)

880

208

HR

HR

$41

$41

$j6 100

S8500YEARS! 1 0 (Phase 1)Downgradient Treatment Plant (4 hours/week) 208 HR $41 $8500YEARS 1 1 0 Elm A venue (Phase 1 )Well Sock Replacement (1 week/6 months) 80 HR $41 $j 300

OXIDIZER REQUIREMENTElm Well Line Years 1 10 (Pnase 1)Thirty 6 socks per well for 1 7 wells 2 per year(changed every 6 months)

1 020 Sock $70 S71 400

DIRECT PUSH INJECTION EFFORTS (One per year)TAIL TREATMENT PHASE 1 YEARS 1 102i Injection and 1 0 Sample Points Over OneMonthInjection Sampling (On site Lab)Oxidizer (875 pounds per effort)Injection Effort Coordination 1 Level PIperson for 10 8 hour days per injection event

1

1875

80

LS

LSIb

HR

$75 000

$17000$1000

S67

$7^ 000

$17000$8800$5400

Recondgur d Alternative 10

September 25 2002Second Street Downgrad ent Plume

0461120112

49

TABLE 13 (Continued)Present Worth Cost Estimate

Reconfigured Alternative 10 Active Remediation/Groundwater Extraction andTreatment and In Situ Bioremediation

Cost Estimate ComponentGROUNDWATER MONITORING (Analysis Only) +

Years 1 through 5 (Phase 1)Quarterly sampling of 21 monitoring wells forVOCs and Naphthalene (standard turnaround)Years6throu h 10 (Phase 1 continued)Semi annual sampling of 21 monitoring wellsfor VOCs and Naphthalene (standard

Years 11 through 15 (Phase'')Annual sampling of 1 5 monitoring wells forVOCs and Naphthalene (standard turnaround)Years 16 through 30 (Phase 3)Annual sampling of 1 1 monitoring wells forVOCs and Naphthalene (standard turnaround)

GROUNDWATER MONITORING (Labor only)Years 1 through 5 (Phase 1)2 Le el PI persons for 1 8 and 7 10 hour daysper sampling event and 2 8 nour da>s per dataevaluation reportYears 6 through 10 (Phase 1 continued)9 Le el PI persons for 1 8 and 7 10 hour da\sper sampling e\ enl and 2 8 hour da>s per dataevaluation reportYears 1 1 through 1 3 (Phase 2)2 Level P] persons for 1 S and 5 10 hour dayspe sampling event and 2 8 hour days per dataevaluation reportYears 16 through 30 (Phase 3)2 Level P 1 persons for 1 8 and 4 10 hour daysper sampling event and 2 8 hour dajs per dataevaluation report

TREATMENT PLANT NPDES AND PROCESS MONI

Source Area Treatment Plant Effluent NPDESMonitoring (Biannual monitoring for VOCs andNaphthalene standard turnaround one duplicateper year) (Years 1 30 Phases! 2 and 3)

Pine Avenue Treatment I lant ProcessMonitoring (Biannual air monitoring for VOCsand Naphthalene standard turnaround oneduplicate per year) (Years 1 30 Phases! 2and 3)Downgradient Treatment Plant NPDESMonitoring (Quarterly water monitoring forVOCs and Naphthalene standard turnaroundone duplicate per year) (Phase 1 Years! 10)

Quantity

92

46

16

12

7:>2

376

148

128

TORINOj

3

5

Units

EA

EA

EA

EA

HR

HR

HR

HR

EA

EA

EA

Unit Cost

S350

$350

$350

$350

$67

$67

$67

$67

$350

$2^0

$350

Capital Cost Annual Cost

$32 200

$16100

$5600

$4200

$50 400

$25 200

$9900

$8600

$1 100

S700

$1 800

Reconfigured Alternative 10

September 26 2002Second Street Oowngrad ent Plume

0461120112

50

TABLE 13 (Continued)Present Worth Cost Estimate

Reconfigured Alternative 10 Active Remediation/Groundwater Extraction andTreatment and In Situ Bioremediation

Cost Estimate Component Quantity Units Unit Cost Capital Cost Annual CostREMEDIAL ACTION PLAN PREPARATION (Year 1 Only)

Preparation of Health and Safety PlanPreparation of 0<SLM ManualPreparation of QA/Sampling Plan

Fi\e Year Review® 5 10 15 20 25 and30yrsDirect Push Sampling of North Edge of Plume (Years 49 14 19 24 and 29)

408060

11

HRHRHRLSLS

$67$67$67

$15450$15 100

$2700$5400$4000

$15500$15 100

MAINTENANCE ALLOWANCESource and Pine (includes C02 feed) (\ ears 130 Phases 1 2 and 3)Downgradient System (?5/ of purchasedequipment delivered) (Years 1 10 Phase 1)Allowance for Redevelopment of Pine AvenuIWA Wells (Years 1 11 and 21)Allowance for Redevelopment of Elm Avenue InSitu Bioremedialion Wells (Year 10) A

1

1

217

LS

LS

LSWell

$3000

$12625

S10000$0

TOTAL PRESENT WORTH O&M COSTTOTAL PRESENT WORTH

\$4 904 000$6 475 000

$3 000

$12 600

$20 000$0

3 9 percent discount rate used to calculate present worthElectrical costs include costs to operate 1 P hp extraction well pump and a 10 hp discharge pump 24 hr/day 365 day/yrFor each sampling event includes one duplicate per 20 primary samplesIt is assumed that the Elm Avenue in situ bioremediation wells will not have to be redeveloped

during their 10 year op rational life

Recon igured Alternali e 10

September 26 2002

Second Street Downgradient Plume

0461120112

information and data collected during the engineering design of the Selected Remedy This is anorder of magnitude engineering cost estimate that is expected to be within +50 to 30 percent ofthe actual project cost

12 4 Expected Outcomes of the Selected Remedy

The expected outcome of the Selected Remedy is that further migration of thedowngradient contaminated ground water plume will be prevented and the concentration ofcontaminants in the ground water will be reduced below health based clean up levels provided itis combined with a suitable remedy for the source area Upon achieving the clean up levels forground water there will be no limitations on its use

130 Statutory Determinations

Under its legal authority the EPA s primary responsibility at Superfund sites is to ensurethat remedial actions achieve adequate protection of human health and the environment Inaddition Section 121 of CERCLA establishes several other statutory requirements andpreferences These specify that when complete the selected remedial action for this site mustcomply with applicable or relevant and appropriate environmental standards established underfederal and state environmental laws unless a statutory waiver is justified The selected remedyalso must be cost effective and utilize permanent solutions and alternative treatment technologiesor resource recovery technologies to the maximum extent practicable Finally the statuteincludes a preference for remedies that employ treatment that permanently and significantlyreduce the volume toxicity and mobility of hazardous wastes as their principal element Thefollowing sections discuss how the selected remedy meets these statutory requirements

13 1 Protection of Human Health and the Environment

The Selected Remedy will protect human health and the environment by achieving theremedial action objectives established for the subsite provided it is combined with a suitableremedy for the source area Levels of contaminants in the ground water will be reduced to levelsconsidered by the EPA to be safe for human consumption In the short term protection isprovided by ground water use restrictions which will prevent exposure to the contaminatedground water The Selected Remedy will support the final ROD for this subsite m beingprotective of human health and the environment

132 Compliance With ARARs

The ARARs for the Selected Remedy are listed in Section 10 2 of this ROD Thechemical specific ARARs were used to establish the ground water clean up levels and will becomplied with provided the Selected Remedy is combined with a suitable source area remedyThe Selected Remedy will comply with all action and location specific ARARs identified inSection 10 2

52

13 3 Cost Effectiveness

The EPA believes the Selected Remedy is cost effective and represents a reasonablevalue 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 §300430(f)(l)(n)(D)) This was accomplished by evaluating the overall effectiveness ofthose alternatives that satisfied the threshold criteria (i e were both protective of human healthand the environment and ARAR compliant) Overall effectiveness was evaluated by assessingthree of the five balancing criteria in combination (long term effectiveness and permanencereduction in toxicity mobility and volume through treatment, and short term effectiveness)Overall effectiveness was then compared to costs to determine cost effectiveness Therelationship of the overall effectiveness of the Selected Remedy was determined to beproportional to the costs and hence represents a reasonable value for the money to be spent

The estimated present net worth cost of the Selected Remedy is $6 475 000 Althoughthe cost of the other alternatives is less the EPA believes that the Selected Remedy is moreprotective, and thus is more cost-effective

13 4 Utilization of Permanent Solutions and Alternative Treatment Technology tothe Maximum Extent Practicable

This interim action is not designed or expected to be the final remedy for this subsiteHowever the Selected Remedy provides the best balance of trade offs among the alternatives interms of long-term effectiveness reduction of toxicity mobility, or volume achieved throughtreatment short-term effectiveness, implementabihty and cost given the scope of the actionThese issues will be dealt with more thoroughly in the final ROD for this subsite

135 Preference for Treatment as a Principal Element

The preference for treatment as a principal element of the remedy will be addressed in thefinal ROD for this subsite, although the Selected Remedy for this operable unit of the subsite hastreatment components including extracting and treating contaminated ground water, that supportthe preference for treatment

136 Five-Year Review Requirements

If there are hazardous substances pollutants or contaminants remaining at a site abovelevels that would allow for unlimited use and unrestricted exposure pursuant to Section 121(c)of CERCLA and NCP §300 430(f)(5)(m)(C) the EPA shall conduct a review of such remedialaction no less often than each five years after the initiation of the remedial action to assure thathuman health and the environment are being protected The Hastings Ground WaterContamination site requires a statutory five year review

53

14 0 Documentation of Significant Changes

The Proposed Plan for tjie Second Street subsite, OU #20: was released for publiccomment in October 2002 The Proposed Plan identified Alternative 10 in situ bioremediationand pumping treating and discharging ground water as the Selected Remedy The EPAreviewed the comments received dunf?^ the public comment period It has been determined thatno significant changes to the^niMy 'asfongmally identified in the Proposed Plan are necessaryor appropriate based upon the comments received

54

RESPONSIVENESS SUMMARYHastings Ground Water Contamination Site

Second Street Subsite, Operable Unit #20Hastings, Nebraska

Introduction

This Responsiveness Summary has been prepared in accordance with the ComprehensiveEnvironmental Response Compensation and Liability Act (CERCLA) as amended by theSuperfund Amendments and Reauthonzation Act (SARA) and the National Contingency Plan(NCP) 40 CFR §300 430(f) This document provides the United States EnvironmentalProtection Agency s (EPA s) response to all significant comments received on the ProposedPlan from the public during the 30 day public comment period

On October 5,2002, the EPA released the Proposed Plan and Administrative Record Filewhich contains the pertinent documents for the subsite The Proposed Plan discussed the EPA sproposed actions to address contaminated ground water The public comment period began onOctober 5 2002, and ended on November 5 2002 The EPA held a public meeting on October17 2002 at the Hastings Public Library to present the Proposed Plan and provide the public anopportunity to comment A copy of the transcript from the public meeting is included in theAdministrative Record File

Comments Received from the Public and Responses

The following comments were received verbally or in writing during the public meetingThere were no additional comments received dunng the public comment period In some casesseveral people made similar comments about an issue Similar comments have been groupedtogether whenever they can be addressed by a single response

Comment 1Mike Felix the Supervisor of the Remediation Section of the Nebraska Department of

Environmental Quality (NDEQ) stated that NDEQ believes that efficient source control needs tobe addressed in the Feasibility Study Proposed Plan and Record of Decision for this subsite

ResponseThe EPA is conducting a separate Remedial Investigation/Feasibility Study for the source

area at this subsite Any proposed remedy for the source area will be the subject of a separateProposed Plan which will also be made available for public comment

Comment 2Rick Sheehy the Mayor of the city of Hastings made the statement that if the decision

were a local one they would not fund this cleanup project since among other reasons they are

not currently using water from the area of the subsite for drinking water and do not think theywill need to use it in the future Similarly Joe Patterson City Administrator asked if it wouldmake sense to just monitor the subsite

ResponseIf no action were taken there are no assurances where the ground water contamination

emanating from this subsite would end up Also while there may not be any current intentionsto utilize this ground water there is no guarantee that it won t be needed at some point m thefuture

The option of just monitoring the ground water was considered during the investigationof this subsite It is the opinion of the EPA s ground water experts with the Robert S Ken-Environmental Research Center taking into consideration the mass of contamination at thissubsite and the speed at which the ground water is moving that the natural processes that occurin the subsurface would not alone be effective at removing the contamination and achieving therequired state and federal clean up levels However some of this approach was incorporatedinto the selected remedy with the idea that if additional oxygen were introduced into thesubsurface the microbial activity could be enhanced We believe this is a more efficientapproach to addressing the contamination at this subsite than pumping and treating alone

Comment 3The Mayor of the city of Hastings a representative of the Hastings Area Chamber of

Commerce and the Director of the Hastings Economic Development Corporation made similarcomments stating that if the Preferred Remedy at this subsite is to have any financial impact onthe city as a responsible party then the preference is that no action be taken It was asked thatthis subsite be designated as an orphan site

ResponseShort of a settlement agreement between the city and the United States that has been

approved by a court the EPA cannot make a commitment regarding enforcement actions thatmay or may not be taken in the future with respect to this subsite However if the EPA were topursue contribution from the city in the future, most likely the EPA will take into account thecity s ability to pay considering the entire Hastings Ground Water Contamination site not justthis subsite

The EPA does have a policy concerning orphan shares at sites where one or moregenerators of waste have gone out of business and other generators may be asked to shoulder theshare of the defunct parties EPA discretionary policy allows settlements where the share of theremaining viable parties may be reduced in a settlement to take account of the orphan sharethat the settling parties would otherwise (given joint and several liability under CERCLA) berequired to pay That policy does not cover this subsite where the only known liable parties(including the defunct parties) are owners and operators rather than generators However arange of other EPA policies may be applicable to any settlements at this subsite

Comment 4Ken Fike asked whether decisions on this subsite will be based on the ability to pay and

if the Superfund is cut will the city of Hastings have to pay*?

ResponseDecisions regarding the remedy selected at this subsite are not based on the ability of any

party to pay for the cleanup Based on the assumption at this point that the United States willprovide funding for this cleanup and seek the required ten percent matching funds from the stateof Nebraska, the EPA has planned for funding in our budgets present and future in order to fundthe cleanup of this subsite Whether this funding is actually provided will be determined in thefuture under applicable budget processes We cannot rule out EPA seeking reimbursement fromthe city of Hastings or any other responsible party in the future (EPA policy does not allow sucha promise of non enforcement) but it seems likely that the city's share of any suchreimbursement would in the end be limited by its limited ability to pay based on what iscurrently known about the city s finances in relation to the overall size of its potential liabilitiesat the Hastings Groundwater Contamination Site

Comment 5Dave Wacker City Engineer expressed concern about the need for adequate public input

and information while designing the locations for oxygen release wells

ResponseDuring the design of this portion of the remedy the EPA and/or its contractors will be

contacting any property owner directly affected by the location of these wells and will seek toobtain access agreements prior to work on their property The EPA will also hold an availabilitysession in Hastings prior to finahzation of the design so that members of the public may comeand view plans and ask questions If a problem with the location of an element of the remedyarises the EPA will make an effort to resolve the problem in an acceptable manner

Comment 6Ken Fine asked whether all gasification plants were Superfund sites and whether the cost

to clean up other gasification plant sites was 10 20 or 50 million dollars

ResponseNot all former manufactured gas plants (FMGPs) are Superfund sites Mike Felix

Supervisor of the Remediation Section of the Nebraska Department of Environmental Qualitystated at the public meeting that they were aware of approximately twenty FMGPs in Nebraskaand that they had just begun preliminary investigations on some of them EPA Region 7 whichencompasses Nebraska Iowa Kansas and Missouri is addressing more than 10 FMGPSuperfund sites in the region and nationally the EPA is working on a number of additionalFMGP sites in the Superfund program The contamination at many FMGP sites is beingaddressed by state environmental agencies The Second Street subsite was identified duringinvestigations of other subsites that comprise the Hastings Ground Water ContaminationSuperfund site

While there is no comprehensive source of information to refer to respond to the questionregarding the costs to clean up other FMGP sites it is safe to estimate that some FMGP siteshave required only a very modest expenditure to determine that no remediation was necessarywhile at other sites extensive remediation has been deemed necessary and those costs mayexceed the specified amounts The costs associated with remediation can become quite high ifthe contamination is extensive

Comment 7Chuck Neumann asked how many more people have gotten cancer or chromosome

aberrations due to the subsite

ResponseThe baseline human health risk assessment that was performed on this subsite did not

attempt to determine whether anyone has presently been adversely affected by the subsite Thatis because no one is currently using the contaminated ground water therefore it is not expectedthat anyone is presently adversely affected by exposure to this water The risk assessmentlooked at what adverse affects might be expected if people were to be exposed to thecontaminated ground water in the future assuming nothing were done to limit exposure

Comment 8Leon Davis asked if there were any instances where the water that the people of Hastings

are drinking is contaminated

ResponseThe EPA is not aware of any contamination in drinking water that is currently being

supplied within Hastings

Comment 9Leon Davis asked if the plume is very decisively outlined and whether it is known where

the ground water plume is traveling Along the same lines the Mayor asked what distance theaquifer moves in one year

ResponseIn the area of the Second Street subsite the contaminated ground water plume is fairly

well defined However there is additional investigation that will be conducted during theremedial design to more thoroughly determine the extent of the plume particularly in the areaeast of Elm Street More thorough definition of the plume is needed in both the horizontal andvertical directions Also additional sampling and analysis will be conducted during the remedialdesign to determine the extent of the polycyclic aromatic hydrocarbons (PAHs) with theexception of naphthalene within the contaminated plume Naphthalene is excluded because theextent of naphthalene contamination is well known

The ground water in the area of the subsite moves about one half to one foot per dayHowever, the contaminants may not move at the same speed as the water At the Second Streetsubsite the contaminants appear to be moving at a slower rate than the ground water possibly

due to the limited solubility that some of the contaminants have in water Some contaminantswould rather adhere to soil than move through the water

Comment 10The Mayor asked how much the past costs are on the Second Street subsite

ResponseThe estimate of total costs incurred by the EPA at the Second Street subsite through

September 30 2002 is approximately eight million dollars This includes not only the amountspaid directly to EPA s contractors but also indirect costs frequently referred to as overheadcosts

Comment 11Mike Sullivan who represents the city of Hastings stated that it was his hope that the

Fund Lead actions that the EPA was undertaking with state participation won t be treated in thefuture as past costs

ResponseThe costs paid for by the EPA Superfund program will accumulate in EPA s Superfund

accounting system just as are other costs spent by the Superfund at this site and other sites TheEPA has not made any decision or any commitments regarding the ultimate recovery of anymonies spent on this subsite

_ «-*fctfe