Decision SummaryCimarron Mining Corporation SiteOperable Unit 2 (Sierra Blanca)Record of Decision

September 1991

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Decision SummaryCimarron Mining Corporation SiteOperable Unit 2 (Sierra Blanca)Record of Decision

August 1991

DECLARATION FOR THE RECORD OF DECISIONCIMARRON MINING CORPORATION SITEOPERABLE UNIT 2 (SIERRA BLANC A)

CARRIZOZO, NEW MEXICOStatutory Preference for Treatment as aPrincipal Element is Metand Five-Year Review is Not Required

SITE NAME AND LOCATIONCimarron Mining Operable Unit 2 (Sierra Blanca)Carrizozo, Lincoln County, New Mexico

OF BASIS AND PURPOSEThis decision document presents the selected remedial action forthe Cimarron Mining Operable Unit 2 (Sierra Blanca) site inCarrizozo, Lincoln County, New Mexico, which was chosen inaccordance with the Comprehensive Environmental Response,Compensation and Liability Act of 1980 (CERCLA) , as amended by theSuperfund Amendments and Reauthorization Act of 1986 (SARA) and,to the extent practicable , the Nat ional Oil and Ha z ardousSubstances Pollution Contingency Plan (NCP) .This decision is based upon the contents of the administrativerecord file for the Cimarron Mining Corporation site.The United States Environmental Protection Agency and the NewMexico Environment Department (NMED) agree on the selected remedy.ASSESSMENT OF THE SITEActual or threatened releases of hazardous substances from thissite, if not addressed by implementing the response action selectedin this Record of Decision (ROD) , may present an imminent andsubstantial endangerment to public health, welfare, or theenvironment .DESCRIPTION OF THE SELECTED REMEDYThis final remedy addresses remediation of soil and waste pilecontamination at the Cimarron Mining Corporation Operable Unit 2(Sierra Blanca) mill location. The principal threats posed by thesite will be eliminated or reduced through treatment andengineering controls.The major components of the selected remedy include:

o Solidification/stabilization of contaminated soils and wastepiles exceeding 500 ppm lead and onsite disposal.o Ground Water Monitoring- The ground water monitoring program may be amended and/oreliminated if data indicates effective remediation has occurred.In addition to the soils and waste pile remedy, the followingmeasures will be implemented:o Removal of the process chemical drums, and decontamination oftanks and associated piping;o Filling in the discharge pits and cinder block trench withonsite soils and covering with clean fill;o Inspection and maintenance of the existing fence.STATUTORY DETERMINATIONS

The selected remedy is protective of human health and theenvironment, complies with Federal and State requirements that arelegally applicable or relevant and appropriate to the remedialaction, and is cost-effective. This remedy utilizes permanentsolutions and alternative treatment technologies (or resourcerecovery) to the maximum extent practicable and satisfies thestatutory preference for remedies that employ treatment thatreduces toxicity, mobility, or volume as a principal element.Because this remedy will not result in hazardous substancesremaining onsite above health-based levels, a five-year review ofthe remedial action is not required.

Robert E. Layton Jr., P.E. DateRegional AdministratorU.S . EPA - Region 6

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DECLARATION FOR THE RECORD OF DECISIONCIHARRON MINING CORPORATION SITEOPERABLE UNIT 2 (SIERRA BLANCA)

CARRIZOZO, NEW MEXICOStatutory Preference for Treatment as aPrincipal Element is Metand Five-Year Review is Not Required

SITE NAME AND LOCATIONCimarron Mining Operable Unit 2 (Sierra Blanca)Carrizozo, Lincoln County, New MexicoSTATEMENT OF BASIS AND PURPOSEThis decision document presents the selected remedial action forthe final operable unit of the Cimarron Mining Corporation site inCarrizozo, Lincoln County, New Mexico, which was chosen inaccordance with the Comprehensive Environmental Response,Compensation and Liability Act of 1980 (CERCLA), as amended by theSuperfund Amendments and Reauthorization Act of 1986 (SARA) and,to the extent practicable, the National Oil and HazardousSubstances Pollution Contingency Plan (NCP).This decision is based upon the contents of the administrativerecord file for the Cimarron Mining Corporation site.The United States Environmental Protection Agency and the NewMexico Environment Department (NMED) agree on the selected remedy.ASSESSMENT OF THE SITE

Actual or threatened releases of hazardous substances from thissite, if not addressed by implementing the response action selectedin this Record of Decision (ROD), may present an imminent andsubstantial endangerment to public health, welfare, or theenvironment.DESCRIPTION OF THE ffEIiRCTED REMEDYThis final remedy addresses remediation of soil and waste pilecontamination at the Cimarron Mining Corporation Operable Unit 2(Sierra Blanca) mill location. The principal threats posed by thesite will be eliminated or reduced through treatment andengineering controls.The major components of the selected remedy include:

o Solidification/stabilization of contaminated soils and wastepiles exceeding 500 ppm lead and onsite disposal.

o Ground Water MonitoringInstall two additional ground water monitoring wells.

- The ground water sampling program, to be developed in theOperation and Maintenance Plan, may be amended and/or eliminatedif data confirms effective remediation of the site has occurred.

In addition to the soils and waste pile remedy, the followingmeasures will be implemented:o Removal of the process chemical drums, and decontamination oftanks and associated piping;o Filling in the discharge pits and cinder block trench withonsite soils and covering with clean fill;o Inspection and maintenance of the existing fence.STATUTORY DETERMINATIONSThe selected remedy is protective of human health and theenvironment, complies with Federal and State requirements that arelegally applicable or relevant and appropriate to the remedialaction, and is cost-effective. This remedy utilizes permanentsolutions and alternative treatment technologies (or resourcerecovery) to the maximum extent practicable and satisfies thestatutory preference for remedies that employ treatment thatreduces toxicity, mobility, or volume as a principal element.Because this remedy will not result in hazardous substancesremaining onsite above health-based levels, a five-year review ofthe remedial action is not required.

Robert E. Layton Jr., P.E . DateRegional AdministratorU.S . EPA - Region 6

Table of ContentsPage

I . Location and General Description . . . . . . . . . . iII. Site History and Enforcement Activities . . . . . . 1Figure 1 - Site Location Nap . . . . . . . . . . . 2Figure 2 - Site Map . . . . . . . . . . . . . . . . 4III. Community Participation

IV. Scope and Role of the Operable Unit . . . . . . . . 6V. Site Characteristics . . . . . . . . . . . . . . . . 7Figure 3 - Estimated Extent of Areas RequiringRemediation . . . . . . . . . . . . . . 8

Figure 4 - Estimated Extent of Soils and WastePiles Exceeding 500 ppm lead . . . . . 10VI. Summary of Site Risks . . . . . . . . . . . . . . . 11

Table 1 - Risks from Ingestion of Compounds in Soil . 13Table 2 - Risks from Dermal Contact with Chemicalsi n Soils . . . . . . . . . . . . . . . . 14Table 3 - Risks from Inhalation of Dusts . . . . . . 15Table 4 - Metals Detected at Elevated Concentrationsby Media . . . . . . . . . . . . . . . . . 17Table 5 - Oral Reference Doses for Contaminants ofConcern . . . . . . . . . . . . . . . . . 18Table 6 - Carcinogenic Slope Factors for Contaminantso f Concern . . . . . . . . . . . . . . . . 19Table 7 - Summary of Risks Associated with Potential

Future Exposure . . . . . . . . . . . . . 22VII. Description of Alternatives . . . . . . . . . . . . 23VIII. Summary of Comparative Analysis of Alternatives . . 26

IX. Selected Remedy . . . . . . . . . . . . . . . . . . 32X. Statutory Determination . . . . . . . . . . . . . . 32

XI. Documentation of No Significant Changes . . . . . . 33XII. Responsiveness Summary . . . . . . . . . . . . . . . 34

Community Preferences . . . . . . . . . . . . . . 34Integration of Comments . . . . . . . . . . . . . 34Attachment 1 - Integrated Uptake/Biokinetic ModellingAttachment 2 - Identification and Evaluation of RemedialAction Requirements

Decision SummaryCimarron Mining Corporation SiteOperable Unit 2Record of DecisionI. LOCATION AND GENERAL DESCRIPTION

The Sierra Blanca milling location near Carrizozo, New Mexico,has been identified as an Operable Unit (OU) 2 of the CimarronMining Corporation Superfund site as a result of contaminationof soils with arsenic and metals. The facility, which is nolonger operating, utilized precious metal extraction processeswhich resulted in unpermitted discharge of contaminatedliquids, and the stockpiling of approximately 570 cubic yardsof contaminated materials piles and other waste sediment.Ground water is not contaminated and no surface water existsnear the site. The site is 7.5 acres in size, relativelyflat, and is located in T8S, R10E, Section 11, east of U.S.Highway 54 (Figure 1). Figure 1 shows the location of bothmill sites (i.e. Operable Unit 1 and Operable Unit 2), andtheir relative positions to each other and the town ofCarrizozo, which has a population of approximately 900. Oneresident is located directly adjacent to the site and theprimary residential population is approximately 1/2 milenorth/north-west of the site. Access to Sierra Blanca isrestricted by a barbed-wire fence and locked gates.II- SITE HISTORY AND ENFORCEMENT ACTIVITIES

The Sierra Blanca Facility is an inactive mil 1 originallyowned by Scott-Tex, Inc., and used to recover a variety ofmetals from ores transported to the site. The milltemporarily shut down in the early 1970' s , and the Town ofCarrizozo eventually became owner of the site. In 1979, thesite was leased under the name of "American Minerals RecoveryCorporation." Notes acquired from the laboratory in the mainon-site processing building indicate that the facilityoperators were attempting to recover silver from various orematerials. It has been reported that the operators claimedthat platinum was also recovered from the ore material. AnNew Mexico Environment Department (NMED) site inspectionreport prepared on 11/18/80 states that "this operationextracts whatever there is a market for - one week gold, thenext silver, platinum and so on."The Sierra Blanca mill was designed and operated similarly tothe Cimarron mill with the exception that cyanide wasapparently not used at Sierra Blanca. For a short period oftime, the two mills were apparently operated concurrently andby the same people. EPA and NMED site file informationdiscusses a possible spill at Cimarron which prompted millingoperations to be relocated to Sierra Blanca in June of 1982.

MOO-"

Scum: US6S, Cub Mountain 7.9* Quod.. 1M1. Contioio Erat Corrhozo «M. * Church Mountoki 7.5' Quoit.. 1912.

FIGURE 1SITE LOCATION MAPSIERRA BLANCA OPERABLE UNfTCARRIZOZO. NEW MEXICO

NEWMEXICO

The Sierra Blanca milling location includes two buildings,four discharge pits, one cinder block trench, a septic tanksystem, and numerous process tanks and materials piles.A 1975 U.S . Soil Conservation Service aerial photograph (USDA,SCS, 1983) shows that the site included only a single building(Process Building 1), and no discharge pits and only a fewmaterials piles in 1975. Sometime between 1980 and 1984,discharge pits, process tanks, and more materials piles wereadded.An NMED memo dated March 6, 1980, states that there were twobuildings at the site, each owned by a different individual.According to the memo, the southern building (Process Building1) was owned by Sierra Blanca Mining and Processing Co. andhoused operations consisting of mechanical separation of goldfrom its natural ore. The ore material was reportedly fromthe Jicarilla Mountain area in south-central New Mexico. Thesouthern building (Process Building 2) was owned by DoubleEagle Mining Co. , which planned to chemically extract goldfrom ore. The memo indicates that this ore was transferredfrom the Cimarron site. The memo states that Double EagleMining Co. maintained extraction equipment both inside andoutside of the northern building.A February 1985, NMED Site Inspection Report described thesite as an "abandoned ore-processing mill with 2 linedimpoundments, an underground storage tank, 2 above groundtanks and a small unlined pit." The lining in theimpoundments was noted to be torn. The actual on-siteinspections were performed in April, May, and June, 1984.Subsequent investigations performed by CDM-FPC under contractto EPA have resulted in the identification of contaminatedmaterials above health based levels.It should be noted that portions of the facility have beendismantled, sold, moved, and/or removed. The current sitefeatures are shown on Figure 2. The material pile locationsand outlines are approximate.The extensive RI field work and feasibility study began in May1990 and was completed in June 1991. The data generated wasused to estimate the extent and magnitude of contamination atthe Cimarron Mining site and to develop and review remedialalternatives. The alternatives evaluated included varioustreatment alternatives for the soils and waste piles,institutional controls, and no action.

COWErOR\ IMP-34 "OFFER

PROCESSBUUNNG

DISCHARGECT4

NOTE: LOCATIONS AMD DIMENSIONS OfMATERIAL PILES. TANKS, AND MILLINGEQUIPMENT ARE APPROXIMATE

LEGEND

MATERIAL PILE LOCATIONMP-00 MATERIAL PILE DESIGNATION—X—— FENCE

MP-03

FIGURE 2SITE MAP

III. COMMUNITY PARTICIPATION

Community interest in the Cimarron Mining site has beenrelatively high due to the close proximity of the site to thetown of Carrizozo.Major community interest has focused on alleviating the stigmaof a hazardous waste or Superfund site as it relates to thecommunity and the desire to have an expeditious solution toallow future industrial development of the site.A public "open house1* workshop was conducted in May 1989 toinform the community of the general RI/FS activities plannedand the Superfund process and to answer any questions.Approximately 35 people attended, including out-of-townindividuals and representatives of the local newspaper and theNew Mexico Bureau of Mines.Questions and comments ranged from concerns regarding thelevel of site contamination, potential impacts on thecommunity and possible solutions to a disregard for theprevious analytical data from the site and an unwillingnessto accept the potential of long term impacts from the sitecontamination.In March 1990, a second public workshop, primarily forCimarron Operable Unit 1, was conducted to notify thecommunity of the preliminary RI results and to answerquestions. Approximately 25 people attended this workshop.Most questions evolved around potential remedial solutions andthe schedule of future activities. A major portion of themeeting involved discussions of the Cimarron Operable Unit 2(Sierra Blanca) site and the responsible party status of thetown of Carrizozo, which leased the property to the operatorsof the mill.Numerous informal status briefings have been conducted withvarious interested citizens and local officials includingpresentations, by invitation, at the local chapter of theRotary Club.The public participation requirements of CERCLA sections113 (K) (2) (B) (i-v) and 117 have been met. The RI/FS documentsfor the Cimarron Mining Operable Unit 2 (Sierra Blanca) siteand a Proposed Plan of Remedial Action were released forpublic comment in June 1991. Public notices were publishedin the lJ.ncoln County News. fact sheets were mailed tointerested individuals, and the documents were made availablefor review in local repositories. A public meeting to discussthe Proposed Plan was conducted on June 17, 1991.

Approximately 15 people attended the public meeting. Mostcomments ( from 2 comaentors ) on the proposed plan ofsolidification/stabilisation and onsite disposal focused onthe potential for off site disposal of the treated soils. Nocomments were presented which adamantly opposed thesolidification and on site disposal alternative. Officialsrepresenting the Town of Carrizozo also had no commentregarding the proposed remedy.The responsiveness summary presented on page 21 providesfurther details regarding the comments received at the publicmeeting. No additional comments were received during the 30day public comment period, which ended on July 10, 1991.

IV. SCOPE AND ROIiJK QF THE OPfiRAflTjE ?NITThe Cimarron Operable Unit 2 (Sierra Blanca) RI/FS has beenperformed in accordance with EPA's National Contingency Planunder the Comprehensive Environmental Response Compensationand Liability Act (CBRCLA) , and the Super fund AmendmentsReauthorization Act (SARA) . This will be the final operableunit for this site.The overall objectives of the RI/FS are:o To collect and evaluate data to determine the extent of

surficial contamination at the site.o To collect and evaluate data to determine if subsurfacecontamination has occurred in either the soils or ground

water.o To collect and evaluate data to characterize the shallowsubsurface geology and hydrogeology.o To determine if ground water from nearby residential wellshas been affected by site activities.o To evaluate human health and environmental risks posed by

site-related contamination identified during the RI.o To identify potentially applicable or relevant andappropriate regulations (ARARs) for response actions.o To identify and evaluate remedial alternatives to addresshuman health and/or environmental risks.Based on the evaluation of the milling process, findings ofprevious investigations, and results of the RI fieldinvestigation, the sources and the areas of environmentalcontamination at the Sierra Blanca site have been delineated.

The remedy outlined in this Record of Decision represents thefinal remedial action at the site and will address theprincipal threats which are posed by the lead contaminatedsoils and materials piles.V. SITE CHARACTERISTICS

In contrast to the Cimarron site, the Sierra Blanca propertyis not contaminated with cyanide. At Sierra Blanca, theground water has been found to be unaffected by past siteoperations; but some soils, tank sediments, discharge pitsediments, and waste pile soils contain high concentrationsof various metals, particularly lead. Typical backgroundconcentrations of lead in the area average approximately13 ppm (parts per million), whereas onsite concentrationsrange as high as 4 6 , 4 0 0 ppm.EPA has issued a directive establishing interim soil cleanuplevels of 500-1000 ppm lead at Superfund sites (OSWERDirective 19355.4-02, EPA, 1989) . These levels represent safeonsite levels assuming either a residential or industrialfuture use, respectively. EPA has established 500 ppm as themost appropriate soil level for this site. This is aconservative level in that it assumes future residential useof the property.Figure 3 depicts the areas of the Sierra Blanca property whichare contaminated with lead concentrations above 500 ppm.Other metals besides lead are also found at elevatedconcentrations at the site. These elements are arsenic,barium, beryllium, copper, lead, manganese, mercury, silver,and zinc. Lead, however, represents the most significantthreat to human health, and therefore lead is considered theprincipal threat at the site. The cleanup of these othercompounds will be incidental to the lead cleanup.Based on the results of the RI, approximately 43 cubic yardsof tank sediments, 182 cubic yards of material pile soils androck, and 345 cubic yards of discharge pit sediment and sitesoils are contaminated with lead at levels above 500 ppm.Referring to Figure 3, for the tank samples analyzed for lead,the maximum on-site lead concentration is 4 6 , 4 0 0 . 0 ppm. Seventanks (TS-01-TS-07) contained lead at concentrations above 500ppm. The average concentration of lead in all tanks sampledis 12 ,049 ppm.Lead in the various waste piles on site has a maximumconcentration of 18 ,900 .0 ppm. The contaminated waste pilesare HP-01, HP-02, MP-03, HP-26, and HP-32. In contrast to the

TS-005

TS- 006TS

0TS-003

PROCESSBLOG. 1INSET

•004

LEQEND3 WASTE MATERIAL WHICH PASSED TCLP|H WASTE MATERIAL WHICH FAILED TCLP FOR LEAD-X— SITE BOUNDARYMP ORE PILET5 TANKSS CONTAMINATED SOIL ^.^. --M-( _FIGURE 3

ESTIMATED EXTENT OF AREAS WfTHLEAD CONCENTRATIONS GREATER THAN 500 PPM

tank sediments, where the majority of samples indicate highelevated concentrations of lead, only four of the 34 wastepile samples analyzed indicate contamination with lead atlevels in excess of the 500-1000 ppm guidance levels. Twopiles, MP-01 and MP-26, with lead concentrations of 18 ,900 ppmand 18,700 ppm, respectively, are the only piles thatdemonstrate significantly elevated lead levels. All otherwaste pile samples contain lead at concentrations of 114 ppmor less.The maximum level of lead in surface soils at the site is10 ,409 ppm, with an overall average concentration of 1470 ppm.Although surface soil and waste pile samples collected at thesite indicate highly elevated concentrations of lead in someareas, the contamination has been found to be limited to 6"to 18** in depth. The contaminated soils areas are shown inFigure 2 as SS-02 and SS-05.It is important to note that the various types of contaminatedmaterial at the site differ in physical characteristics. Thematerials vary considerably with respect to particle size.The tank sediments, discharge pit sediments, and site soilsconsist of fine particle size soils, whereas the material inthe material piles ranges in size from soil particles toboulder size rocks. The materials also vary with respect totheir leaching potential.As part of the sampling program, select samples were analyzedusing Toxicity Characteristic Leaching Procedure (TCLP) forthe elements of concern: arsenic, barium and lead. The TCLPanalysis is a procedure for evaluating a material's abilityto release contaminants to the environment. The samples werechosen to be representative of contaminated tank sediments,surface soils, material piles, and discharge pit sediments.Only the samples of tank sediments and material piles failedthe TCLP test for lead. All of the samples passed the TCLPtest for arsenic and barium.This indicates that the metals present in soils and dischargepit sediments are tightly bound within the soil and thatmigration of arsenic and the metals of concern from dischargepit sediments and contaminated surface soils to deeper soilsand groundwater is not likely to occur. However, lead in thematerial piles 1, 2, 3, 26, and 32, as indicated in Figure 4,does have the potential for such migration via leaching. Iftanks were spilled or dispersed on the ground, lead migrationcould also occur.

UOENOMATERIAL WTTH LEAD CONCENTRATIONSGREATER THAN 500 PfM

FIGURE 4ESTIMATED AREAL EXTENT OF ELEVATED METALS CONCENTRATIONSIN SURFACE SOILS, DISCHARGE PIT SEDIMENTS, & MATERIAL PILES

With respect to the remedial action at Sierra Blanca, the TCLPresults help to direct the cleanup. Those materials whichfail the TCLP test will have to undergo more stringenttreatment to control potential migration of contaminants thanthose materials which pass the test. In accordance with EPAPublication 9347.3-12FS dated January 1991, titled "Super fundGuide to RCRA Management Requirements for Mineral ProcessingWastes, " mineral processing waste is subject to hazardouswaste regulations under RCRA Subtitle C if it meets thedefinition of a RCRA hazardous waste (i.e. a listed waste orexhibits a characteristic, as in failing the TCLP test) .Alternative remedial approaches to the Sierra Blanca wastematerials are further discussed below in this Decision Summaryand in the Feasibility Study for Sierra Blanca.

VI. SUMMARY OF SITE RISKSThe objective of the Risk Assessment was to determine whetheror not the substances present at the Sierra Blanca sitepresent potential human health risks. Risks were evaluatedby incorporating Sierra Blanca, or Operable Unit 2 (OU2)contaminant concentration data into tables previouslydeveloped for the risk assessment portion of the Cimarron(OU1) RI/FS. This data table is used due to the similarityof contaminants and the geographical proximity of the twosites. Media evaluated included surface soil, material piles,discharge pit and tank sediments, and ground water. The RiskAssessment evaluated the potential cancer and noncancer healthrisks associated with incidental ingestion of soils from thesite, dermal contact with soils from the site, and inhalationof windblown dust containing site-related contaminants.Groundwater is not evaluated since the groundwater has beenfound to not be contaminated with site related contaminantsof concern.Base.Due to the lack of an accepted oral reference dose (Rfd) forlead, the primary contaminant of concern at Sierra Blanca, itis difficult to quantify the current baseline risks. However,any exposure to elevated concentrations of lead canpotentially result in elevated blood lead levels, particularlyin children.At the present time there are no final regulatory standardsfor lead in soils. As previously stated, EPA has issued adirective establishing interim soil lead cleanup levels of500-1000 ppm at Super fund sites (OSWER Directive #9355.4-02,

11

EPA, 1989) . These levels represent safe onsite levels basedon acceptable inhalation/ingestion risks, assuming either aresidential or industrial future use, respectively. EPA hasestablished 500 ppm as the most appropriate soil level forthis site. This is a conservative level in that it assumesfuture residential use of the property.EPA currently suggests the use of a computer model, referredto as the Uptake Biokinetic Model, for helping to verify orrefine cleanup goals. This model was used taking intoconsideration all potential sources (air, soil, water, etc.)of lead exposure with regards to site specific aspects of theSierra Blanca mill and the Carrizozo area, for generating asafe level. The results of this modeling (Attachment 1)indicate that a 500 ppm lead cleanup level is safe andappropriate.Actual or threatened releases of hazardous substances fromthis site, if not addressed by implementing the responseaction selected in this Record of Decision (ROD), may presentan imminent and substantial endangerment to public health,welfare, or the environment.Exposure AssessmentA degree of conservatism is built into the risk calculationsin several areas. First, all exposures evaluated are for ahypothetical future on-site population. Assumptions in theexposure evaluation include residential development on thecontaminated site, 30 years of residence at that location, andthat every day during that period is spent on the site. Asdescribed in the OU1 RI report the evaluation of surface soilsassumes that soil to which ingestion or dermal exposure occurscontains all site-related contaminants at the maximum leveldetected in surface soils. Because contaminant concentrationsvary at different locations at the site and exposure tomaximal concentrations for all contaminants by one individualis unlikely, this overestimates any combination of exposuresthat could actually occur at the site and maximizes the riskestimates generated by the risk calculations. This approachis regarded by EPA as sufficient to characterize risks in thislevel of analysis. If such as evaluation indicates thatcontaminants from the site do not present an appreciablehealth risk, even under these "worst case" exposureassumptions, it can be assumed that exposures associated withmore plausible exposure scenarios are also without appreciablerisks. Tables 1, 2, and 3 present the calculations andparameters used to estimate ingestion, dermal absorption, andinhalation exposures in this assessment.

12

TABLE 1RISKS FROM

INGESTION OF COMPOUNDS IN SOIL

Lifetime Cancer Risk - xCCancer Potency Factor]

[ CS X IR X CF X FI x EF x ED 1 .--..,x AT X[CPF]

Hazard Index * [Daily Exposure] + [Reference Dose]_ f CS x IR x CF x FI 1 .

where:CS - concentration of chemical in soil (mg/kg) - compound specificIR - ingestion rate (ing soil/day) - 200 for child; - 100 for adultCF ~ conversion factor (10~6 kg/mg)FI « fraction ingested from contaminated source «• 100%EF •• exposure frequency (days/yr) - 1, current; » 365, futureED - exposure duration (years) ** 1, current; <= 30, futureAT » averaging time (days) « 25,550BWL = average lifetime bodyweight (kg) « 70 kgBWT « bodyweight at time of exposure (kg) » 15 kg (child)CPF - cancer potency factor (mg/kg-d)"1 - compound specificRfD - reference dose (mg/kg-d) - compound specific

TABLE 2RISKS FROM

DERMAL CONTACT WITH CHEMICALS IN SOIL

Lifetime Cancer Risk - [ Lib*orbZdADoiiJg* lx[Canccr Potency Factor]

CS x CF X SA X m X ABS X EF X ED 1x AT " " " " JX[CPF]

Hazard Index - [Daily Absorbed Dose] + [RfD]CS x CF x SA x LR x ABS .

where:CS * concentration of chemical in soil (mg/kg) - compound specificCF - conversion factor (10"* kg/mg).SA - surface area of skin available for contact (cm2/ event) - 2,100

cm2 child; - 5 , 3 0 0 cm2 adultIR - loading rate of soil on skin (rag/ cm2) - 0.5 mg/cm2

ABS - absorption fraction (unitlesa) - 1%EF » exposure frequency (events/year) « 1/yr for current scenario;-= 260 ages 1-5 (5 times/wk) , 104 thereafter (2 times/ wk) forfuture.ED » exposure duration (years) « 1 current; * 3O futureBWt » average lifetime body weight (kg) = 70 kgBW. • bodyweight at time of exposure (kg) « 70 kg adult; » 15 kg

childAT « averaging time (days) - 25,550CPF » cancer potency factor (mg/kg-d)"1 - compound specificRf.l) = reference dose (mg/kg-d) - compound specific

TABLERISKS FROM

INHALATION OF DUSTS

Lifetime Cancer Risk f Lifetime Average lxfUnit Risk Pact0riL Daily Exposure JxtUnit Risk Factor]

CD X CF. X CF.X RD X ED X WFAT X [URF]

where:CDCF,CF2

RDEDWF

ATURF

concentration of contaminant in dust (mg/kg) - compound specificconversion factor #1 (10* Mg/mg)conversion factor #2 (10~* kg/fig)concentration of respirable dust in air (f*g/m3) - 12exposure duration (years) - 30 yearsfraction of time wind blows toward receptor (unitless)« 10%, current; « 100%, futureaveraging time (years) * 70 yearsunit risk factor (pg/n5)'1 - compound specific

Toxicitv AssessmentThe Hazard Quotient (HQ) approach to evaluation of potentialhealth risks assumes that there is a level of exposure belowwhich it is unlikely for even sensitive populations toexperience adverse health effects. If the HQ exceeds unity( 1 ) , there may be concern for potential systemic effects. Asa rule, the greater the HQ above unity the greater the levelof concern. To assess the overall potential for noncancereffects posed by exposure to multiple chemicals, a HazardIndex (HI) approach has been developed based on EPA's"Guidelines for Health Risk Assessment of Chemical Mixtures11.This approach assumes that simultaneous subthreshold exposuresto several chemicals could result in an adverse health effect.The HI is equal to the sum of the HQs. When the HI exceedsunity, there may be concern for potential health effects. Itshould be noted that not all substances present on the siteact on the same target organ or produce the same adversehealth effect. Therefore, summation or the HQs to generatea HI is a conservative estimate of risk.A review of the data indicates that the contaminants ofconcern (COCs) at Sierra Blanca are similar in surface soils,materials piles, and tank sediments. The major COG is lead;however, arsenic and other metals are present in conjunctionwith lead at various locations on the site. The elementsevaluted in the risk assessment are arsenic, barium,beryllium, copper, lead, manganese, mercury, silver, sodiumand zinc. COCs include all of these, with the addition ofsodium. Tank sediment COCs include all those found in soil,with the exception of beryllium. COCs in ground water consistof lead, manganese, and zinc. Table 4 shows all substancesdetected and indicates which substances were found at elevatedlevels, by media. The Reference Doses (RfDs) available forCOCs at Sierra Blanca are listed in Table 5. The ReferenceDoses (Rfds) for the COCs at this site exist only forevaluation of ingestion exposures. No RfD values arecurrently available for evaluation of inhalation or dermalexposures to these COCs. As in the risk assessment for OU1,oral RfDs are used to evaluate potential health risksfollowing dermal absorption of substances. This approachassumes that systemic toxicity is similar following absorptionvia the skin or gastrointestinal tract. This approach was notused for inhalation exposures in the OU1 assessment or in thisreport, as toxicity via this route is frequently specific tothe respiratory tract.Two of the COCs (arsenic and beryllium) are identified asknown or suspected human carcinogens. These are listed in

16

TABLE 4METALS DETECTED AT ELEVATED

CONCENTRATIONS, BY MEDIA*

Compound Soil* * Material Piles Tank Sedimentsarsenicbariumberylliumcopperleadmanganesemercurysilversodiumzinc

XXXXXXXXX

XXXXXXX

XXXXXXXXX

*X indicates that the substance was present at an elevated concentrationonsite. Only those compounds detected at elevated concentrations wereincluded in the human health risk assessment** Including discharge pit sediments.

TABLE 5ORAL REFERENCE DOSES FOR CONTAMINANTS OF CONCERN

Compoundarsenicbariumberyllium (so) salt)copperleadmanganesemercurysilversodiumzincNA = not available

RfD-oral(mg/kg-d)pending7.0E-025.0E-033.7E-02

NAl.OE-013.0E-043.0E-03

NA2.0E-01

UncertaFacto

3100NA

11000

2

10

Uncertainty Modifying TcndcityFactor Endpomt

11

NA

blood pressurenone

G! irritation

CNS effectskidney effectsgrey coloration

of the skin

anemia

ReferenceIRISIRISIRIS

HEAST

IRISHEASTIRIS

HEAST

TABLE 6CARCINOGENIC SLOPE FACTORS

FOR CONTAMINANTS OF CONCERN

—INHALATION- ~INGESTK>N-~CSF Unit Risk CSF Unit Risk

Compound (mg/kg-d)-l (ug/m3)-l (mg/kg-d)-l (ug/I)-l Classificationarsenic 5.0E+01 4.3E-03 1.8E+00 5.0E-05 Group Aberyllium (sol salt) &4E+00 2.4E-03 4.3E-fOO 1.2B-04 Group B2

Table 6 together with their carcinogenic slope factors (CSFs)for oral or inhalation exposures. Both of these compounds areconsidered to be carcinogenic following either ingestion orinhalation expsoures.Ecological AssementIn addition to human helath evaluations, environmental impactsof the site were evaluated. No endangered species wereidentified on or near the Sierra Blanca site. The primaryopportunity for ecological exposures is through contaminatedsoils which may be incidentally ingested by animals duringfeeding or may be in contact with plant roots. Highconcentrations of lead at Sierra Blanca, and associatedelevated concentrations of other constituents such as arsenicand barium, are not dispersed across the site, but rather arepresent in distinct and separable locations on-site.Contaminated materials are found in discharge pit sediments,material piles, tank sediments, and two well defined smallareas of surface soils.The remedial action to be conducted at Sierra Blanca willentail treatment and disposal of the contaminated material insuch a way that the material will no longer be available forcontact by humans or animaJLs. Since the contaminated materialis only located in the above specific areas of the sie, ratherthan scattered across the site as is the case at manySuperfund sites, a remedial action directed at those specificcontaminated areas will effectively remove ecological threatsas well as human health risks. Analyses performed based onavailable data indicate that using the 500 ppm lead soilcleanup level ensures no significant ecological threats at theSierra Blanca Hill.Risk Assessment ff\HMnarvAs stated previously, the risk calculations performed in thisreview are conservative. Maxiumum concentrations ofcontaminants are used in all but the inhalation exposurecalculations, even though the maximum concentrations do notoccur in the same sample locations. Additional conservatismis added by the summation of the Hazard Quotients due to thefact that not all of the COCs may act on the same target organor produce the same adverse health effect. Additionally, onlythe exposures by hypothetical future on-site residentpopulation are used in calculating the HQ and carcinogenicityof each contaminant. This hypothetical population is expectedto endure the highest exposure to site-related contaminants,and so experience the greatest health risks.

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Arsenic and beryllium are evaluated for carcinogenicityfollowing inhalation exposure to surface soil. The summedlifetime cancer risk is l.OE-06, with individual cancer riskof l.OE-06 and 2.5E-08 for arsenic and beryllium,respectively. Generally, a carcinogenic risk value of l.OE-04 to l .OE-07 is within the range of target risk levels EPAhas identified as acceptable in the NCP.Calculations of surface soil ingestion exposure show a summedHI of 3.2E+00 with the highest HQ of 1.4E+00 presented bybarium. As mentioned earlier, only arsenic and beryllium areevaluated for lifetime cancer risk following ingestionexposure. Lifetime cancer risk for these constituentsfoillowing surface soil ingestion is calculated as 9 .3E-04.Material pile soil ingestion exposure calculations reveal asummed HI of 4.3E+00, with HQs of l .OE+00 and 2.3E+00 forbarium and manganese, respectively. Evaluation of materialpile soil ingestion predicts a lifetime cancer risk of 7.7E-05. Calculations regarding ingestion exposure to tanksediments show individual HQs of 3.01E+00 and 4.4E+00 forbarium and silver, respectively. Tank sediment evaluationreveal an ingestion lifetime cancer risk of 9 .7E-07. Siteground water has been found not be contaminated withcontaminants of concern.Using the future scenario, there are no increased systemicrisks via dermal exposure from any COC in any media. None ofthe summed His or individual HQs for dermal exposure are aboveone. Evaluation of surface soil dermal exposure reveals alifetime cancer risk of 6.IE-05. Evaluation of material piledermal exposure show arsenic to present a lifetime cancer riskof 4.7E-06. Tank sediment dermal exposure calculations reveala lifetime cancer risk of 5.IE-08 for a single exposure.It should be noted that lifetime cancer risk calculations forsurface soil ingestion and dermal exposure are performed usingthe maximum concentration of arsenic of 731 mg/kg. Thisconcentration is an order of magnitude higher than the nexthighest sample of 7 9 . 6 mg/kg or the arithmetic averageconcentration of arsenic in surface soil of 50 .5 mg/kg.Cancer risks associated with these lower concentrations wouldbe nearly one order of magnitude lower. Additionally, itshould be noted that numerous issues relevant to theevaluation of arsenic carcinogenicity, particularly followingarsenic ingestion, have been reviewed and includenonlinearities in the dose-response curve for arseniccarcinogenicity which could reduce the risk posed by a givendose. In combination with the lower concentrations of arsenicfound at most locations on the site, actual risk or cancer

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TABLE 7SUMMARY OF RISKS ASSOCIATED WITH POTENTIAL FUTURE EXPOSURE

FutureScenarioSOILINGESTION

Lifetime - Surface SoilLifetime - Material PilesFrom Tanks

Summed MaximumHazard HazardIndex Quotient Compound

Total PrimaryCancer ContributorRisk to Risk

3.2E+0043E+00

1.4E+002.3E+004.4E+00

bariummanganese

silver9.3E-047.2E-Q59.7E-07

arsenicarsenicarsenic

DERMAL ABSORPTION FROM SOILUfetime - Surface Soil 1.7E-01Lifetime - Material Piles 2.3E-01From Tanks —

7.2E-OZ1.2E-012.3&4H

bariummanganese

silver6.1E-054.7E-065.1E-08

arsenicarsenicarsenic

DUST INHALATIONOnsite Residence l.OE-06 arsenic

could be lower than the values presented in the attachedtables by up to two orders of magnitude. Table 7 summarizesthe His and total cancer risk for each exposure pathway andmedia of concern.VII. DESCRIPTION OF ALTERNATIVES

Numerous remedial alternatives were screened during thefeasibility study process including reprocessing/recycling,soil washing, thermal treatment, biological treatment, offsite disposal in mine shafts, etc. The screening processeliminated those alternatives which were not technicallyfeasible, could not meet State and/or Federal regulations, orwould not be protective of public health and the environment.Subsequent to this detailed screening process, a total of fivealternatives for the sierra Blanca site remediation wereanalyzed in detail. The following alternatives were evaluatedusing the nine selection criteria outlined on page 27 of thisDecision Summary. The details of this evaluation arecontained in Chapters 8, 9, and 10 of the Feasibility Studyreport (Attachment 2).1. No Action2. Institutional Controls3. Cement Solidification/stabilization and On-Site Disposal4. Cement Solidification/stabilization and Off-site MunicipalLandfill Disposal5. Off-Site Municipal Landfill and Hazardous Waste LandfillDisposalALTERNATIVE 1 - NO ACTIONThe No Action alternative (consisting of monitoring only)provides a baseline for reviewing other remedial alternativesfor the Sierra Blanca site. Because no remedial activitieswould be implemented to mitigate contamination present at thesite under this alternative, it is possible that people couldbe exposed to contaminants. With the exception of the removalof the process chemical drums and tank sediments onsite, noreduction in risks to human health and the environment wouldoccur.Capital costs are $17,000 and as with all alternativesevaluated, include installing 2 additional ground watermonitoring wells at the site. Annual operation andmaintenance (0 & M) costs include semi-annual ground watersampling and analysis for metals for a period of 30 years.Present worth of O & M costs is estimated to be $48 ,000 .

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ALTERNATIVE 2 - INSTITUTIONAL CONTROLSUnder this alternative, no active remedial measures todirectly address contamination at the site would beimplemented; rather, legal controls, such as site access andland use restrictions, would be used to minimize thelikelihood of contact with contamination. Monitoring ofground water as described for Alternative 1 is included underAlternative 2 to ensure that the risks to human health arebeing addressed. Institutional control measures that couldbe implemented consist of fencing, land use restrictions ordeed notices, and zoning ordinances which would 1imitactivities on the site. These additional measures will alsobe selectively included as elements of the other remedialalternatives.The use of institutional control measures provide a greaterdegree of protection of human health than the No Actionalternative, however, this alternative will not address thepotential for contaminant migration from the site. Also, longterm effectiveness would likely be low due to difficulties inenforcement.Additionally, this alternative provides no reduction in thetoxicity, mobility, or volume of contaminants at the site assuggested by the Superfund law.Annual costs associated with this remedial action areattributed to ground water monitoring costs. Total estimatedpresent worth cost of this alternative is $93 ,000 .ALTERNATIVE 3: CEMENT SOLIDIFICATION/STABILIZATION AND ON-SITE DISPOSALEPA's Preferred AlternativeAlternative 3 entails treatment of contaminated waste materialthat can leach, followed by onsite disposal of all wastes.Treatment would be accomplished by a fixation process usingPortland cement to stabilize the waste material. The 225cubic yards of waste which failed the TCLP tests (and canleach) are the material piles and the tank sediments,including cinder block trench sediments. Contaminatedsurf icial soils and soils within the discharge pits passed theTCLP tests but remain a health risk due to other potentialexposure routes. This non-leachable fraction will also bedisposed of in the onsite discharge pit.Implementation of Alternative 3 would consist of leasing astandard portable concrete mixer and setting it up on the

24

site. Portland cement of a type to be determined based onbench scale tests would be purchased and stockpiled on-site,together with any supplemental sand or aggregate required toachieve the mix design.The contaminated material piles would be excavated anddischarged into the cement mixer, where the material would bemixed with Portland cement, water, and any supplemental sandor aggregate required. The resulting concrete mixture wouldthen be transported to the discharge pit and deposited. Non-leachable contaminated surficial soils and sediments withinthe contaminated discharge pits would be excavated anddisposed directly without treatment. An impermeable cover,the specifications of which will be determined in the designphase, will be incorporated to restrict the infiltration ofprecipitation. The discharge pit would then be covered withclean soils. Two additional monitoring wells will also beinstalled as an extra precautionary measure to ensureprotection of the ground water.Alternative 3 would be highly protective of human health andthe environment, as the wastes would be treated to preventleaching. Additionally, this alternative would achievecompliance with all State and Federal regulations. A highdegree of long-term effectiveness and permanence would beachieved since the waste's mobility would be significantlyreduced. Due to the known reliability of the stabilizationtreatment method for the contaminated material, it isanticipated that monitoring can be significantly reducedcompared to Alternative 1 and 2, therefore, monitoring costshave been reduced accordingly. Alternative 3 is readilyimplementable with an estimated present worth cost of $79 ,000 .ALTERNATIVE 4; CEMENT SOLIDIFICATION/STABILIZATION AND OFF-SITE MUNICIPAL LANDFILL DISPOSALAlternative 4 also involves cement solidification/fixationtreatment of the leachable portion of the Sierra Blanca wastematerial, followed by transportation together with excavatednon-leachable wastes to a suitable off-site municipal landfillfor final disposal. This alternative is similar toAlternative 3, except that final disposal of the wastes wouldbe in an off-site landfill. Transportation of the wasteswould be accomplished in standard public highway-approved bulkcarrier trucks, of approximately 40 ,000 Ib. capacity, whichwould be covered to control dust.Alternative 4 would reduce the mobility of the wastes throughtreatment. Implementation of this alternative would providea reasonable degree of short-term effectiveness, providedappropriate precautions and control measures such as dustcontrol are instituted during the remediation phase.

25

As with Alternative 3, Alternative 4 would be highlyprotective of human health and the environment since thewastes would be treated. The estimated present worth cost ofAlternative 4 is $235,000.ALTERNATIVE 5: OFF-SITE MUNICIPAL AND HAZARDOUS WASTE

In lieu of treatment of the leachable portion of the SierraBlanca waste material, an alternate approach would be todispose of it in an off-site hazardous waste landfill.Alternative 5, therefore, consists of excavating the leachablewastes and transporting them without treatment to a suitablehazardous waste landfill. Because there is no requirement todispose of the non-leachable wastes in a hazardous wastelandfill, these wastes would be excavated, kept segregatedfrom the leachable wastes, and transported to a municipallandfill for final disposal.Although Alternative 5 would be protective of human health andthe environment, the degree of protect iveness would be lessthan the alternatives involving treatment. Compliance withState and Federal regulations would be achieved as disposalof the wastes in permitted municipal and hazardous wastelandfills is allowed under current regulations. Off sitedisposal without treatment however, is the least preferredremedial action under the Superfund Amendments andReauthorization Act. The estimated present worth cost of thisalternative is $344 ,000 .

VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVESFigure 3 shows the areas of highest lead contamination (inexcess of 500 ppm) . Treatment of these soils and waste pileswould effectively address the principal threats due to leadcontamination, potential ingest ion/ inhalation impacts andpotential migration to ground water. Accordingly, remedialaction alternatives for the site focus on removal of thoseareas of soil contamination and waste piles above 500 ppmlead, with some continued ground water monitoring to ensurelong-term effectiveness.Potential remedial action alternative technologies wereevaluated to address soil and waste pile contamination at theCimarron Mining Operable Unit 2 (Sierra Blanca) site. Thisevaluation was performed by progressing through the series ofanalyses which are outlined in the National Contingency Plan,(NCP) , in particular, 40 CFR Section 300, along with variousguidance documents issued by the EPA, Office of Solid Waste

26

and Emergency Response (OSWER). This process addresses theSuperfund Amendments and Reauthorization Act (SARA) Section121 requirements of selecting a remedial action that isprotective of human health and the environment, that is cost-effective, that at least meets Federal and State requirementsthat are applicable or relevant and appropriate, and thatutilizes permanent solutions and alternative treatmenttechnologies or resource recovery technologies to the maximumextent practicable. Additionally, SARA Section 121 and theguidance documents referenced above require EPA to givepreference to remedies which employ treatment whichpermanently and significantly reduces the mobility, toxicity,or volume of hazardous substance as their principal element.The details of this evaluation are contained in Chapters 8 ,9 ,10 of the Feasibility Study report (Attachment 2).Alternate technologies were identified using best engineeringjudgement following the guidelines presented in Guidance forConducting Remedial Investigations and Feasibility StudiesUnder CKRCIA (SPA, 1988) , Guidance on Remedial Actions forCpntfljainatad Ground Water at Superfund Sites (EPA, 1988) , andthe Handfoopk f or Remedial Action at Waste Disposal Si teg(EPA, 1988) .The initial step in determining the appropriate remedialaction for the Cimarron Mining Operable Unit 2 (Sierra Blanca)site was to identify suitable remediation technologies. Areview and analysis of the available remediation methods wasconducted and feasible alternatives were developed.The detailed evaluation process is a structured format,designed to provide relevant information needed to adequatelycompare and evaluate feasible alternatives to allow selectionof an appropriate remedy for the site by EPA through theRecord of Decision (ROD) process. The remedy must meet thefollowing statutory requirements:o Be protective of human health and the environment;o Attain ARARs (or provide ground for invoking a waiver):o Utilize permanent solutions and alternative treatment

technologies or resource recovery technologies to themaximum extent practicable; ando Satisfy the preference for treatment that reduces toxicity,mobility, or volume as a principal element, or provide anexplanation in the ROD as to why it does not.Nine evaluation criteria have been developed to address thestatutory requirements listed above and to address additionaltechnical and policy considerations that have proven to beimportant for selecting remedial alternatives. These criteriaare listed and briefly described below:

27

o Overall Protection of Human Health and the Environment -How well the alternative reduces risks to human health andthe environment, through treatment, engineering orinstitutional controls.o Compliance with ARARs - How well the alternative complieswith all applicable or relevant and appropriate

requirements or, if a waiver is required, how it isjustified.o Long-Term Effectiveness and Permanence - How well thealternative maintains long-term effectiveness in protection

of human health and the environment. Alternatives whichafford the highest degree of long-term effectiveness andpermanence are those that leave little or no untreatedwaste at the site.o Reduction of Toxicity, Mobility or Volume through Treatment

Anticipate performance of the specific treatmenttechnologies that an alternative may employ and theirability to destroy or irreversibly treat contaminants.o Short-Term Effectiveness - How well the alternative

protects human health and the environment duringconstruction and implementation of a remedy.o Implementability - Whether the alternative is technically

and administratively feasible and whether the requiredgoods and services are available.o Cost - Analysis of capital and 0 & M costs of eachalternative to determine cost-effective remedies. Costestimates are developed with relative accuracy (-30% to

+50%) and are presented as present worth costs so thatalternatives can be reasonably compared.

o State Acceptance - To be completed for the most part afterthe public comment period; this criterion describes thepreferences of the State or support agency.

o Community Acceptance - To be completed for the most partafter the public comment period; this criterion reflectsthe preferences of the community.Below, each of the five alternatives for Cimarron MiningOperable Unit 2 (Sierra Blanca) soil and waste pilecontamination is individually evaluated and then comparativelyanalyzed on the basis of the first seven of the nine criteriaabove. The last two criteria above (State and communityacceptance) were fully addressed after the public commentperiod, the results of which are stated in the ResponsivenessSummary on page 34 of this Decision Summary.

28

Alternative 1Alternative 1, No Action, is implementable; however, itprovides no treatment, engineering, or institutional measuresto control the exposure of receptors to contaminated material.No reduction in risks to human health and the environmentwould occur, therefore this alternative would not be incompliance with ARARS.No controls for exposure, other than the existing fence, andno long-term or short-term site management are included underAlternative 1. This alternative provides no reduction in thetoxicity, mobility, or volume of the contaminated ores, tanksediments, and surficial soils on the site. All existing andpotential future risks associated with the site would remain.With respect to ground water, no effects from sitecontaminants have been detected. With respect to soils,quantifiable risks are present which consist of hazardsarising from potential exposure to lead, with limitedadditional effects from other metals.Alternative 2The use of institutional control measures, Alternative 2,provides a greater degree of protection of human health thanthe No Action alternative alone, since institutional actioncan reduce the potential exposure of receptors. Access andland use restrictions further limit activities on the propertywhich would minimize exposure risks. While some degree ofhuman health protectiveness would be provided by Alternative2, it would not be protective of the environment since thecontamination will remain.Like Alternative 1, Alternative 2 would not comply with ARARsdue to requirements imposed by RCRA Subtitles C and Dregarding disposal of mining wastes, and due to New Mexicosolid waste regulations. Although reduction in the potentialfor human exposure would be recognized under this alternative,only limited long-term effectiveness would be provided due todifficulties in enforcement of the institutional controlmeasures. Additionally, this alternative provides noreduction in the toxicity, mobility, or volume of contaminantsat the site.Alternative 3Alternative 3, stabilization and on-site disposal, would behighly protective of human health and the environment, as thewastes would be treated to the extent practicable.Additionally, this alternative would achieve compliance with

29

all ARARs. A high degree of long-term effectiveness andpermanence would be achieved. Stabilization is the state-of-the-art technology for immobilizing metals and has beenutilized effectively for many years. Durability tests arebeing conducted on the solidified material as part of thebench scale treatability tests. This information will beutilized in determining the necessary optimum mixture ratiosto ensure the long term effectiveness of this option.Alternative 3 would reduce the toxicity and mobility of thewastes through treatment; however, the volume of the wasteswould not be reduced as a result of cement solidificationfixation treatment. Implementation of this alternative shouldprovide a reasonable degree of short-term effectiveness,provided appropriate precautions and dust control measures areinstituted during the remediation phase. These measures wouldbe those that minimize or prevent exposure hazards to on-siteworkers and adjacent residents during remediation activities.Implementation of this alternative is possible without unduetechnical or administrative difficulty.Alternative 4As with Alternative 3, Alternative 4, stabilization and off-site municipal landfill disposal, would be highly protectiveof human health and the environment since the wastes would betreated, and compliance with ARARs would be achieved. Thedegree of long-term effectiveness and permanence would becomparable to on-site landfill disposal, since a municipallandfill in compliance with current regulations is monitoredclosely.Alternative 4 would reduce the toxicity and mobility of thewastes through treatment. The volume of wastes would,however, be substantially increased as a result of treatment,which would impact transportation costs.Implementation of this alternative should provide a reasonabledegree of short-term effectiveness, provided appropriateprecautions and dust control measures are instituted duringthe remediation phase. These measures would be those thatminimize or prevent exposure hazards to on-site workers andnearby residents during remediation activities.Implementation would be dependant on acceptance of thematerial by the off-site facility.

30

Alternative 5Alternative 5 off-site municipal and hazardous waste landfilldisposal, would be moderately protective of human health andthe environment, although the degree of protectiveness wouldbe less than the alternatives involving treatment. Compliancewith ARARs would be achieved as disposal of the wastes inpermitted municipal and hazardous waste landfills is allowedunder current regulations. A similar degree of long-termeffectiveness and permanence would be provided with thisalternative as compared to on-site landfill disposal.Although treatment would be provided prior to disposal in anon-site landfill, the continuous monitoring and active wastemanagement present in a permitted hazardous waste landfillshould provide a comparable level of protectiveness. Thelong-term effectiveness and permanence of off-site hazardouswaste landfill disposal would be less than treatment anddisposal in a municipal landfill, since treatment of thewastes would be provided prior to disposal in the municipallandfill. Additionally, the level of waste management andwaste monitoring provided is comparable at both facilities.Alternative 5 would reduce the mobility of the wastes as aresult of disposal in a hazardous waste landfill. However,the toxicity and volume of the wastes would not be affected.Implementation of this alternative should provide a reasonabledegree of short-term effectiveness, provided the appropriateprecautions and dust control measures are instituted duringthe remediation phase involving excavation of the contaminatedmaterial.Implementation of this alternative would be dependent onacceptance by the off-site facilities. Off site disposalwithout treatment however, is the least preferred remedialaction under the Superfund Amendments and Reauthorization Act.

Cost Comparison1. No Action $48,0002. Institutional Controls 93 ,0003. Cement Solidification/Onsite Disposal 79 ,0004. Cement Solidification/Offsite Municipal 235 ,000Landfill Disposal5. Off-site Municipal and Hazardous Waste 344 ,000Landfill Disposal

31

IX. g^UflCTPP REMEDYEPA !s selected remedy (Alternative 3) - cement solidification/stabilization and on site disposal has been reviewed andconcurred with by the New Mexico Environment Department. Theproposed alternative, along with the other detailedalternatives, was evaluated and ranked according to the nineselection criteria outlined above. This ensured acomprehensive and thorough study of the benefits of eachalternative. This alternative was found to be the most cost-effective and protective of the alternatives studied.Alternative 3 - Cement Solidification/stabilization and On-site DisposalAlso includes:- removal of process chemical drums and tanks

install two additional monitoring wells, long termmonitoring of the ground water- deed notice of remediation activities- installation of an impermeable cover/cap for the disposalareaFinal Remediation Goal

Point of RemediationChemical Compliance GoalSoils Lead On Site Surface 500 ppmSoils

X. STATUTORY DETERMINATIONActual or threatened releases of hazardous substances fromthis site, if not addressed by implementing the responseaction selected in this Record of Decision (ROD) , may presentan imminent and substantial endangerment to public health,welfare, or the environment.Stabilization of the soil and waste pile material exceeding500 ppm would provide protection of human health and theenvironment by reducing the mobility of the lead in the soilsand its potential for contaminating groundwater. Treatmentwill also ensure that the waste is not a significant ingestionor inhalation risk. Hazard Indices for noncarcinogens at thesite will be less than 1 upon completion of remedial action.

32

activities. Additionally, implementation of the selectedremedy will not pose unacceptable short-term risks or cross-media impacts. The selected remedy also meets the statutoryrequirement to utilize permanent solutions and treatmenttechnologies to the maximum extent practicable.The long-term risks associated with the Sierra Blanca soilsand waste piles contamination would be minimized. Short-termrisks could be addressed by ensuring that airborne dusts arecontrolled during implementation of the remedy. The selectedremedy could be readily implemented, since no specialtechnologies would be required; and the remedy utilizestypical construction techniques.All Federal and State requirements for this remedy that areApplicable or Relevant and Appropriate (ARARs) can be metthrough adequate design and planning.Long-term effectiveness is achieved through solidification andstabilization of the contaminants of concern. In addition,treatment is utilized to the maximum extent practicable inthis alternative.This remedy is cost effective in comparison to otheralternatives. The total cost of the selected remedy isestimated to be $79,000 net present worth dollars (+50% or-30%) . Five-year facility reviews will not be necessary forthe soils since contaminants above health based levels willnot remain. Ground water monitoring will continue for 30years if sample analysis deems it necessary.The selected remedy provides the best balance of tradeoffsamong the selection criteria used to evaluate the fiveproposed alternatives for the site, as discussed in thisRecord of Decision.Community and state acceptance is favorable to this remedy incomparison to other alternatives presented during the publiccomment period.

XI. DOCUMENTATION OF NO SIGNIFICANT CHANGESThe Proposed Plan for the Cimarron Mining Operable Unit 2(Sierra Blanca) site was released for public comment in June1990. The Proposed Plan identified Alternative 3,solidification/stabilization and onsite disposal, as thepreferred alternative. EPA reviewed all comments submittedduring the public comment period. Upon review of thesecomments, it was determined that no significant changes to theremedy, as it was originally identified in the Proposed Plan,were necessary.

33

XII. RESPONSIVENESS SUMMARYCommunity PreferencesBased upon the responses received during the public meeting,it appears that the Citizens of Carrizozo, and town officialshave preference for the selected remedy of solidification/stabilization and onsite disposal. Only one citizen commentedat the public meeting regarding the potential for off sitedisposal and no comments were received from town officials.No additional comments were received during the 30 day publiccomment period, which ended on July 10, 1991. The New MexicoEnvironment Department has provided formal concurrence withthe proposed remedy.Integration, of^ Comments1. Comment: Could soils available on site be used as aneutralizing agent and mixed with the lead contaminatedmaterials to reduce the leaching potential?

Response: No. Athough the soils onsite do provide someneutralizing capacity, the quantity of soil necessary torender the contaminated material non hazardous would bemuch greater than the cement required for the proposedsolidification remedy. Due to the resulting increase inquantity of material to be handled and increased monitoringrequirements, soil neutralization would not be as costeffective nor as protective as the proposed stabilizationremedy.

2. Comment: Are two additional ground water monitoring wellsnecessary?Response: Yes. Based on the studies conducted at thesite, EPA and NMED concluded that two additional groundwater monitoring wells and continued monitoring arenecessary to ensure protection of the local ground waterresources.

3. Comment: Is the solidification/stabilization of leadcontaminated soils an EPA accepted process?Response: Yes. The solidification/stabilization of metalscontaminated soils is the state-of-the-art technology forimmobilizing such contaminants. The technology issuccessful for treating contaminated soils with much higherlead concentrations than those found at "Sierra Blanca".Treatability studies were conducted during the FeasibilityStudy to determine optimum cement/soil mixture ratios andleaching tests indicated the process is highly effective.

34

4. Comment: Why is solidification/stabilization and off sitedisposal not considered a better remedy?Response: Superfund law requires remedies to be costeffective and also directs EPA to give preference to onsite remedies. Disposal off site would be approximatelythree times the cost due to the extremely hightransportation costs and disposal fees, with no increasein protectiveness, over on site disposal.

5. Comment: Is the proposed clean-up level of 500 parts permillion lead safe for the residents of Carrizozo?Response: Yes. This clean up standard presumes that afterremediation the site will be lived upon by families withchildren (who are most sensitive to chronic leadpoisoning). It is EPA's best current scientific judgementthat resulting soil lead levels less than 500 ppm are safefor human beings.EPA utilized a computer model, referred to as the UptakeBiokinetic Model, for helping to verify or refine cleanupgoals. This model was used taking into consideration allpotential sources (air, soil, water, etc.) of lead exposurewith regards to site specific aspects of the Sierra Blancamill and the Carrizozo area, for generating a safe cleanuplevel. The results of this modeling indicate that a 500ppm lead cleanup level is safe and appropriate.

6. Comment: In a layman*s perspective, how many car batterieswould it take to cause the level of lead contaminationfound at "Sierra Blanca"?Response: The lead at this site did not originate frombatteries. A logical comparison can not be made betweenthe lead in car batteries and the minute particles of leadfound in the approximately 570 cubic yards of contaminatedsoils and tank sediments at the Sierra Blanca site.The severity of lead contamination is based on a potentialfor inhalation and ingestion of lead, with 500 parts permillion lead being the health based cleanup criteria. Leadconcentrations at Sierra Blanca range as high as 46 ,400parts per million, or more simply stated, approximately 100times the acceptable health based limit.

35

Attachment 1Integrated Uptake/Biokenetic Modeling

Since there are no USEPA-approved RfD values for lead, it is notpossible to evaluate the noncancer risks of lead by calculation ofan hazard index. An alternative approach is to estimate the likelyeffect of lead exposure on the concentration of lead in the blood(PbB). Several mathematical models have been developed forcalculating the value of PbB as a function of environmentalconcentrations of lead. Of these, the EPA's IntegratedUptake/Biokinetic (IUBK) model called LEAD4 has the greatestflexibility and has been most thoroughly validated, so it wasselected for use here.LEAD4 is a lead uptake biokinetic model which could be used as analternative to calculating Hazard Quotient for lead- LEAD4estimates the likely effect of lead exposure based on theconcentration of lead in the blood of children between the ages of0-84> months. The model was used to evaluate the effect of surfacesoil ingestion on blood lead levels in children ages 0-84 monthsfor the Sierra Blanca site assuming a residential scenario. Themodel LEAD4 is limited to children and can't be used for adults dueto large biological differences.It is commonly agreed that young children are more susceptible tothe effects of lead than older children or adults. This is basedon three facts: 1) young children tend to have higher exposurelevels (especially to soil), 2) young children have higher leadabsorption rates, and 3) the nervous system of infants and youngchildren is more sensitive to the neurological effects of lead.It should be noted that some parameters of the model cannot beadjusted to approximate adult exposure, i .e., ingestion rate,other parameters including specific body compartments could not beadjusted to the adult representative sizes. Therefore, the riskto adults from exposure to lead could not be calculated using themodel. However, we might cautiously assume that concentrationsprotective to children (sensitive population), might be protectiveto adults.The model was applied on data from the site and Carrizozo the area.The percentage of the child population that would exceed thecritical cutoff point of 10 ug/dL blood level was 2 1 .38 based onaverage lead concentrations on site (Figure 1). The percentagecould increase to 99 .99 if the lead exposure concentration is basedon the highest lead concentrations in onsite materials (Figure 2).A value of less than or equal to 5% is generally consideredacceptable. That is 5% of the population will have a chance ofexceeding the cutoff blood lead concentration of 10 ug/dL. For theSierra Blanca site, a soil concentration of 500 mg/kg will achieveless than the 5% value (see Figure 3).

EPA believes that actual or threatened releases of hazardoussubstances from this site, if not addressed by implementing theresponse action selected in this ROD, may present an imminent andsubstantial endangerment to public health, welfare, or, theenvironment*

Figure 1

Input Value: Soil/Dust Lead Concentration = 1470 ppmCutoff! 10.0

X Above! ai.*0X B«IoMl 78.ClG. H**nl 7.7C

« *e e

•* £"2 *3 ?II

!• 19 ••BLOOD LEAD CONCENTRATION

0 to 84 Month*

29

Figure 2

Input Value: Soil/Dust Lead Concentration = 18 ,900 ppmCutoff: 19.0 U0XALyt Akov*: 9t.V*

X B«low: 0.0&G. Mean: 4O.40

II *C 0

«3a v4» «t<M~ en

48 CO 80 188BLOOD LEAD CONCENTRATION

0 to 84 Mont**

120 140 160

Figure 3

Input Value: Soil/Dust Lead Concentration = 500 ppro

M *e o

A 0

Cutoff: 10.•X Afcov*: 8.53X B*low! 99.41G. M«MI: 4.14

4 ft 8 10 12BLOOD LEAD CONCENTRATION <Uff/«IL>

O to 84 Month*

14 1ft

Attachment 2

IDENTIFICATION AND EVALUATION OF REMEDIAL ACTION REQUIREMENTS

8.1 INTRODUCTION

In this Section and the following two Sections, potential remedialaction alternatives are evaluated to address the contamination at theSierra Blanca site. This evaluation is performed primarily byprogressing through the series of analyses which are outlined in theNational Contingency Plan (NCP), in particular, 40 CFR Section 300,the Interim Guidance on Superfund Selection of Remedy, December 24,1986, Office of Solid Waste and Emergency Response (OSWER) DirectiveNo. 9355 .0- 19 , and the Additional Interim Guidance for FY 1987 Recordsof Decision, July 24, 1987 (OSWER Directive No. 9355.0-21) . Thisprocess, in part, enables EPA to address the Superfund Amendments andReauthorization Act (SARA) Section 121 requirements of selecting aremedial action that 1) is protective of human health and theenvironment, 2) meets Federal and State requirements that areapplicable or relevant and appropriate, 3) utilizes permanentsolutions and alternative treatment technologies or resource recoverytechnologies to the maximum extent practicable, and 4) is costeffective. Additionally, SARA Section 121 and the guidance documentsreferenced above require EPA to give preference to remedies whichemploy treatment which permanently and significantly reduces themobility, toxicity, or volume of hazardous substances as theirprincipal element.

Section 121(b) (1) of SARA requires that an assessment be conducted ofpermanent solutions and alternative treatment technologies or resourcerecovery technologies that, in whole or in part, will result in apermanent and significant decrease in the toxicity, mobi1ity, orvolume of the hazardous substances, pollutants, or contaminants. SARArequires that the following treatment alternatives be developed:

"Treatment alternatives should be developed ranging from analternative that, to the degree possible, would eliminate the

8-1

need for long-term management (including monitoring) at the siteto alternatives involving treatment that would reduce toxicity,mobility, or volume as their principal element. Althoughalternatives may involve different technologies (which will mostoften address toxicity and mobility) for different types ofwaste, they will vary mainly in the degree to which they rely onlong-term management of treatment residuals or low-concentratedwastes. In addition to the range of treatment alternatives, acontainment option involving little or no treatment and a noaction alternative should also be developed"

Remedial alternatives are identified using the guidelines presentedin Guidance for Conducting Remedial Investigations and FeasibilityStudies Under CERCLA (U .S . EPA, 1988) , Guidance on Remedial Actionsfor Contaminated Groundwater at Superfund Sites (U.S . EPA, 1988) andthe Handbook for Remedial Action at Waste Disposal Sites (U.S. EPA,1988) .

Analysis of remedial alternatives is based on an evaluation of thefollowing for each alternative:

Degree to which alternative is protective of public healthand the environment.

Degree to which alternative meets applicable or relevantand appropriate requirements (ARARs).

Technical feasibility.

Cost/benefit analysis.

Identification and screening of remedial alternatives for the SierraBlanca site were performed using the following steps:

Development of Remedial Action Objectives (based on ARARs,risk assessment, etc.)

8-2

Development of General Response ActionsIdentification of Volumes and Areas of Contaminated MediaIdentification and Screening of Remedial TechnologiesEvaluation of Process Options as to Effectiveness,Implementability and Relative CostAssembly of Alternatives for Remediation

These steps are detailed in subsequent sections.

8.2 CONTAMINANTS OF CONCERN AND RISK BASED EXPOSURE CRITERIA

As discussed in Sections 4 and 7, groundvater at Sierra Blanca has notbeen impacted by site contaminants and is, therefore, not addressedin the FS.

The contaminant of concern in soils, discharge pit and tank sediments,and material piles at Sierra Blanca is lead. As discussed in Section4 and 7, arsenic and other metals besides lead are found at elevatedconcentrations at the site. However, as discussed in Section 6,arsenic and the other metals present much less risk to human healththan the risks posed by levels of lead found in the same materials atthe site. A concentration of lead in soil exceeding 500*1000 ppm hasbeen established as a cleanup criteria by EPA's office of Emergencyand Remedial Response and Office of Waste Program Enforcement, InterimGuidance on Establishing Soil Lead Cleanup Levels at Superfund Sites(OSWER Directive #93355 .4-02, EPA, 1989) . As discussed in Sections4 and 7, lead levels far in excess of 500 ppm are present in variouswaste materials at the site. Only those areas of the site where leadlevels are high are arsenic and other metals concentrations alsoelevated. By approaching the site remediation in a manner to addressthose areas where lead is found at concentrations above 500 ppm,elevated concentrations of arsenic and other metals will also beaddressed.

8-3

8.3 ARAR-BASED EXPOSURE CRITERIA

Under Section 121 (d ) ( 1 ) of the Comprehensive Environmental Response,Compensation and Liability Act (CERCLA) as amended in 1986 by theSuperfund Amendment and Reauthorization Act (SARA), remedial actionsmust attain a degree of cleanup which assures protection of humanhealth and the environment. Additionally, CERCLA remedial actionsthat leave any hazardous substance, pollutant, or contaminant on-sitemust meet, upon completion of the remedial action, a level or standardof control that at least attains standards, requirements, limitations,or criteria that are "applicable** or "relevant and appropriate" underthe circumstances of the release. These requirements, known as"ARARs", may be waived in certain instances (see Section 121 ( d ) (4) ofCERCLA).

ARARs are derived from both Federal and State laws. Under Section121 (d ) (2) of SARA, the Federal ARARs for a site could includerequirements under any of the Federal environmental laws (e .g . , theSolid Waste Disposal Act, the Clean Air Act, the Clean Water Act, andthe Safe Drinking Water Act) . State ARARs include promulgatedrequirements under the State environmental or facility siting lawsthat are more stringent than Federal ARARs and have been identifiedto EPA by the State in a timely manner. Subparagraph 121 (d) (2) (c) ofCERCLA limits the applicability of State requirements or siting lawswhich could effectively result in the statewide prohibition of landdisposal of hazardous substances, pollutants, or contaminants unlesscertain conditions are met.

Subsection 121(d ) of CERCLA requires that Federal and Statesubstantive requirements which qualify as ARARs be complied with byremedies (in the absence of a waiver). State requirements can bewaived if a State has neither consistently applied nor demonstratedthe intent to consistently apply a requirement in similarcircumstances at other remedial actions within the State (Subparagraphl2 l ( d ) (4 ) (E ) of SARA). Federal, State or local permits do not need

8-4

to be obtained for removal nor for remedial actions implemented onsite (Subsection 121(e) of CERCLA), although substantive technicalrequirements will be attained.

The definitions of "applicable" or "relevant and appropriate"requirements as derived from the NCP are as follows.

Applicable requirements means those cleanup standards, standards ofcontrol and other substantive environmental protection requirements,criteria or limitations promulgated under Federal or State law thatspecifically address a hazardous substance, pollutant or contaminant,remedial action, location, or other circumstance at a CERCLA site.For example, at a site with contaminated groundwater, Federal drinkingwater and State groundwater standards would be "applicable** ifcontaminated groundwater was being directly used as a drinking watersource.

Relevant and appropriate requirements means cleanup standards,standards of control and other substantive environmental protectionrequirements, criteria or limitations promulgated under Federal orState law that, while not "applicable" to a hazardous substance,pollutant, contaminant, remedial action, location, or othercircumstance at a CERCLA site, address problems or situationssufficiently similar to those encountered at a CERCLA site that theiruse is well suited to the particular site. For example, at a sitewith contaminated groundwater, Federal drinking water and Stategroundwater standards would be "relevant and appropriate" if thecontaminated groundwater was not currently being used, but was aviable potential source of drinking water. Requirements may berelevant and appropriate if they would be "applicable" except forjurisdictional restrictions associated with the requirement.

The determination of which requirements are "relevant and appropriate"is somewhat flexible. EPA and the State may look to the type ofremedial actions contemplated, the hazardous substances present, the

8-5

waste characteristics, the physical characteristics of the site, andother appropriate factors. it is possible for only part of arequirement to be considered relevant and appropriate. Additionally,only substantive requirements need to be followed. See 40 CFR Part300, March 8, 1990.

There are three types of ARARs. The first type includes "contaminant-specific" requirements. These ARARs set limits on concentrations ofspecific hazardous substances, pollutants, and contaminants in theenvironment. Examples of this type of ARAR are ambient water qualitycriteria and drinking water standards. A second type of ARAR includeslocation-specific requirements which set restrictions on certain typesof activities based on site characteristics. These includerestrictions on activities in wetlands, floodplains, and at historicsites. The third type of ARAR includes action-specific requirements.These are technology-based restrictions which are triggered by thetype of action under consideration. Examples of action-specific ARARsare Resource Conservation and Recovery Act (RCRA) regulations forwaste treatment, storage and disposal.

ARARs must be identified on a site-specific basis consideringinformation about specific chemicals at the site, specific featuresof the site location, and actions that are being evaluated asremedies. If no ARAR covers a particular situation, or if an ARAR isnot sufficient to protect public health or the environment, then non-promulgated standards, criteria, guidance, and advisories may be usedto provide a protective remedy.

Tables 8-1 and 8-2 contain a listing of ARARs which have beenevaluated for Sierra Blanca. These tables identify each potentialARAR and whether or not it is "applicable" or "relevant andappropriate". The remainder of this analysis describes and evaluatesthe three types of ARARs in greater detail.

8-6

Page 1 of 7

TABLE 8-1

DETERMINATION OFAPPLICABLE OR RELEVANT ADD APPROPRIATE

FEDERAL STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

Standard, R*quirement,Criteria, or Limitations citation Descripti

Applicable/Relevant andAppropriate CO! ts

Relevant Standards(Units Shown)

SAFE DRINKING HKTGR ACT

- National Primary DrinkingWater Standards

42 USC { 300g40 CFR Part 141

National Secondary DrinkingHater Standards

40 CFR Part 143

Maximum Contaminant LevelGoals

Underground injectionControl Regulations

Pub. L No. 99-330,100 Stat. 642 (1986)

40 CFR Parts144-147

Establishes health—basedstandards Cor public watersystems (maximum contami-nant levels)

No/No

Establishes welfare-basedstandards for public watersystems (secondary maximumcontaminant levels)

Establishes drinking waterquality goals set at levelsof no known or anticipatedadverse health effects,with an adequate margin ofsafetyProvides for protection ofunderground sources ofdrinking water

NO/NO

No/No

No/No

Not ARAR because the sitegroundwater has not beencontaminated by site-related activities.

Hot ARAR because the sitegroundwater has not beencontaminated by site-related activities.

Not ARAR because the sitegroundwater has not beencontaminated by site-related activities.

Ho underground injection currentlyenvisioned as remedial alternative(see New Mexico entries, followingpages, regarding ground waterprotection standards).

As - 0 .05 mg/LPb - O .OS mg/LCd - 0.010 mg/LHg - 0.002 mg/LCr - 0 .05 mg/LSe - 0 .01 mg/LBa - 1 mg/LNitrate (as N) - 10 mg/LAg - 0 . 0 5 mg/L

Cu - 1 mg/LMn - 0 .05 mg/LFe - 0.3 mg/LpH - 6.5 to 8.5SO - 250 mg/LTDS - 500 mg/LZn - 5 mg/LCl - 250 mg/LAS - 0 .05 mg/LPb - 0 . 0 2 mg/L (withdrawn)Cu - 1.3 mg/LCr - 0 . 12 mg/LHg - 0 .003 mg/LSe - 0.045 mg/L

Page 2 of

TABLE 8-1

DETERMINATION OFAPPLICABLE OR RELEVANT AND APPROPRIATE

FEDERAL STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

Standard, Requirement,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate CO! >ts

Relevant Standards(Units Shown)

CLEAN HATER ACT

- Hater Quality Criteria33 USC $S 1251-137640 CFR Part 131Quality Criteriafor Hater

Sets criteria for waterquality based on toxicityto aquatic organisms andhuman health

No/No Human health criteria not ARARbecause no contamination ofgroundwater or surface wateris attributable to the site.

CLEAN AIR ACT

- National Primary andSecondary Ambient AirQuality Standards

— National Emissions Standardsfor Hazardous Air Pollutants

42 USC SS 7401-764240 CFR Part 50

40 CFR Part 61

Establishes standards for HO/NOambient air quality toprotect public health andwelfare (including standardsfor participate matter andlead)Sets emission standards for No/Nodesignated hazardous pollu-tants including Mercury,beryllium, and inorganic

Ho point source air emissionsexist on site.

No air emissions of hazardouspollutants are generated atthe site.

- National Emissions Standardsfor Hazardous Air Pollutants

40 CFR Part 61,140-161, 156

Specifies control require-ments for asbestos handlingand work practices tocontrol emissions

No/No Does not specify a threshold contami-nant level. No asbestos apparenton site.

BE90IHKT! CONSERVATION ANDRECOVERY ACT

- Subtitle C (hazardous waste)

42 USC S$ 6901-6987

40 CFR Part 265,Subpart Q, Sections264.288 fc 264.310

Amended Solid Haste DisposalActSpecific closure require-ments for impoundments andlandfills

No/Yes Consolidation on-site does notinvoke RCRA; however, generalRCRA guidelines are appropriate.

Page 3 of /

TABLE 8-1

DETERMINATION OPAPPLICABLE OR RELEVANT AND APPROPRIATE

FEDERAL STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

standard, Requirement,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate

Relevant Standards(Units Shown)

tcrsam sftcnncRESOURCE CONSERVATION ANDRECOVERY ACT

- Subtitle C (hazardous waste)

42 USC $S 6901-698'?

40 CFR Part 265,Subpart G

- Subtitle D (solid wastes) 40 CFR Part 241 ,et. seq.

Amended Solid Waste DisposalActSpecifies closure require— No/YesMnts for hazardous wasteimpoundments and landfills

Specifies requirements for Yes/Yesland disposal of solid wasteincluding industrial wastes

wastes from the extraction, bene-ficiation, and processing of oresand Minerals are currently excludedfrom regulation under HCRA.However, on-site disposal of miningwaste occurred after November19, 1980.If mining waste were to be disposedof in a sanitary or industrial land-fill. Subtitle D regulations wouldapply. Not applicable foron-site actions.

- Subtitle I (undergroundstorage tanks)

FEDERAL MINE SAFETY AND HEALTHACT

40 CFR Part 280

30 USC SS 801-962

Establishes regulations No/Norelated to undergroundstorage tanksRegulates working condi- No/Notions in underground Binesto assure safety and healthof workers

Underground storage tanks are notpresent on—site, and are not beingconsidered Cor remediation.Under 40 CFR $ 300 .38 , all appli-cable health and safety require-ments apply to all responseactivities under the NCP; nounderground workings are onsite, however.

CLEAN WTER ACT- national Pollutant DischargeElimination system

40 CFR Parts 122,125

Requires permits for thedischarge of pollutantsfrom any point source intowaters of the United States

No/No A permit is not required for on-site CERCLA response actions, butthe substantive requirements apply.However, no remediation or dischargeof on-site grounduater or surfacewater is planned.

Ui.j

Page 4 of

TABLE 8-1

DETERMINATION OPAPPLICABLE OR RELEVANT AND APPROPRIATE

FEDERAL STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

Standard, Requirement,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate Comments

Relevant Standards(Units Shown)

- Effluent Limitations

- National PretreatmentStandards

TOXIC SUBSTANCES CONTROL ACT

- PCS Requirements

40 CFR Part 440

40 CFR part 403

15 USC $S 2601-2629

40 CFR Part 761

URANIUM MILL TAILINGS RADIATION 42 USC $ 7901-7942OOMTBOL ACT 42 USC $ 2022

OCCUPATIOHU. SAFETY AND HEALTHACT

29 USC S 651-678

Sets technology-based No/Noeffluent limitations forthe Ore Mining and DressingPoint Source CategorySets standards to control No/Nopollutants which passthrough or interfere withtreatment processes inpublicly owned treatmentworks or which may contam-inate sewage sludge

Establishes storage and Ho/Nodisposal requirements forPCBsEstablishes requirements No/Norelated to uranium miltailingsRegulates worker health and Yes/Yessafety

Applies to ongoing miningand dressing operations.

No water treatment or dischargeto POTH is planned.

No PCBs are identifed on the site.

Uranium is not present on-site.

Under 40 CFR S 300.38 , requirementsof this Act apply to all responseactivities under the HOP.

D.O.T. HAZARDOUS MATERIALTBAMSMKTATiaM RBOULATIOWS

49 CFR Parts 107,171-177

Regulates transportation ofhazardous materials

Yes/Yes Will apply if selected remedialalternative involves transportationof hazardous materials.

Page 5 of 7

TABLE 8-1

DETERMINATION OFAPPLICABLE OR RELEVANT AND APPROPRIATE

FEDERAL STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

Standard, Requirement,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate

Relevant Standards(Units shown)

MATIONAL HISTORIC PRESERVATIONACT

16 USC $ 47040 CFR S 6 .301 < b )36 CFR Part 800

ARCUEOLOGICAL AND HISTORICPRESERVATION ACT

16 USC S 46940 CFR $ 6301 ( c )

HISTORIC SITES, WILDINGS ANDANTIQUITIES ACT

PISH AMD WILDLIFE COORDINATIONACT

16 USC $$ 461-46740 CFR $ 6 .301U)

16 USC SS 661-666

Requires Federal agencies to No/Notake into account the effectof any Federally-assistedundertaking or licensing onany district, site, building,structure, or object that isincluded in or eligible forinclusion in the NationalRegister of Historic PlacesEstablishes procedures to No/Noprovide for preservation ofhistorical and archeologicaldata which aught be destroyedthrough alteration of terrainas a result of a Federalconstruction project or aFederally licensed activityor progranRequires Federal agencies to No/Noconsider the existence andlocation of landmarks on theNational Registry of NaturalLandmarks to avoid undesirableimpacts on such landmarksRequires consultation when No/NoFederal department or agencyproposes or authorizes any•edification of any streamor other water body andadequate provision for protec-tion of fish and wildliferesources.

The remedy does not affect anydistrict, site, building, structure,or object listed on or eligible forthe National Register.

The remedy does not affect historicalor archeological data.

The remedy does not affect any NaturalLandmark.

There are no natural streams or otherwater bodies on-site.

Page 6 of 1

TABLE 8-1

DETERMINATION OFAPPLICABLE OR RELEVANT AND APPROPRIATE

FEDERAL STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

Standard, Requirement,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate COHMRtS

Relevant Standards(Uiits Shown)

BED SPECIES ACT

CLEAN WATER ACT

— Dredge or Fill Requirements(Section 4 0 4 )

16 USC 153150 CTR Part 20050 CFR Part 402

33 USC SS40 CFR Parts 230,231

Requires action to conserve No/Noendangered species withincritical habitats upon whichendangered species depend

Requires permits for dis- No/Nocharge of dredged or fillmaterial into navigablewaters

None of the endangered speciesindigenous to Lincoln County were foundon the site in a survey conducted bythe U.S. Fish and wildlife Service.

There will be no discharge of dredgedor fill material into navigable watersas part of the remediation.

RIVERS AND HARBORS ACT OF 1899

- Section 10 Permit

EXECUTIVE ORDER ON PROTECTIONOF WETLANDS

EXECUTIVE ORDER ON FLOODPLAINMMIWCMDfT

HILDCKBCSS ACT

13 USC $ 403

33 CFR Parts 320-330

Exec. Order No.1 1 ,99040 CFR $ 6 . 302 ( a )and Appendix A

Exec. Order No.1 1 ,988

16 USC 1131SO CFR 35. 1

Requires permit for struc- No/Notures or work in or affect-ing navigable watersRequires Federal agencies to No/Noavoid, to the extent possible,the adverse iapacts associatedwith the destruction or lossof wetlands and to avoidsupport of new constructionin wetlands if a practicablealternative exists.Requires Federal agencies to No/Noevaluate the potential effectsof actions they may take ina floodplain to avoid, to theadverse iapacts associatedwith direct and indirectdevelopment of a floodplainAdminister Federally owned Ho/Nowilderness area to leaveit unimpacted

There will be no structures or workin or affecting navigable waters.

No remedial action is being consi-dered that would affect a wetland.

The site is not within a 100-yearfloodplain, according to FEKA maps.

No wilderness area on-site or adjacentto site.

Page 7 of 1

TABLE 8-1DETERMINATION OF

APPLICABLE OR RELEVANT AND APPROPRIATEFEDERAL STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

Standard, Requirement,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate Coi HltS

Relevant Standards(Units Shown)

RATIONAL WILDLIFE REFUGE SYSTEM

SCENIC RIVER ACT

CQJkSTAL ZONE MANAGEMENT ACT

16 USC 66850 CFR 27

16 USC 127140 CFR 6 .302 ( e )16 USC 1451

Restricts activities within No/Noa National Wildlife RefugeProhibits adverse effects on No/Noscenic river.Conduct activities in accor— No/Nodance with State approvedManagement program.

No Wildlife Refuge on-site or adjacentto site.No scenic river in area.

Area is not in the coastal zone.

i.

Page 1 of 4

TABLE 8-2

DETERMINATION OPAPPLICABLE OR RELEVANT AND APPBOPRIATE

STATE STANDARDS, REQUIREMENTS, CRITERIA, AND LXHITATIOtlS

Stand* rd, Requirement,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate ints

Relevant Standards(Units Shown)

swcincNEW HEXICO HATER QUALITY ACT Hew Mexico Statutes,

Title 74, Article 6Surface and subsurface withinor bordering upon New Mexico

Creates the Water Quality ControlCommission, which has the dutiesand powers to set water qualitystandards and to regulate effluentto surface and subsurface waters.

- New Mexico Mater QualityControl Commission Require-ments* Toxic Pollutant Criteria 1- 101 .u .U. Water contaminant(s J;

groundwater of < 10 ,000 TBSEffluent discharge toground water

Ho/No Not ARAR because the site hasnot resulted in groundwatercontamination; th« uppersaturated zone is a Class IIIAaquifer; because no groundwatercontamination was found; andbecause no treatment or reinjec-tion of groundwater is proposed.

Arsenic (As)Barium (Ba)Cadmium (Cd)Chromium (Cr)Cyanide (CN)Fluoride (F)Lead (Pb)Total Mercury (Hg)Nitrate (HO as N)Selenium (se)

0.1 mg/L1-0 mg/L0 . 0 1 mg/r,0 . 0 5 mg/r.0.2 mg/L1.6 mg/L0 . 0 5 mg/r0 . 0 0 2 mg/10 .0 mg/r0 . 0 5 mg/r0 . 0 5 mg/r5.0 mg/L

Silver (AgJUranium (U)Radioactivity: Combined

Radium-226 andRadium-228

BenzenePolychlorinatedbyphenyls (PCBs)

TolueneCarbonTetrachloride

1 , 2-dichloroethane(EDC)

1,1-dichloro-.ethylene ( 1 , 1-DCE ) 0 .005

1,1,2,2-tetrachloro-•thylene (PCE) 0 . 0 2

1,1,2-trichloro-

30 .0 pCi/0.0 1 mg/r0 .00 1 mg/0 . 7 5 mg/i0.010 .0 1

TABLE 8-2

DETERMINATION OFAPPLICABLE OB RELEVANT AND APPBOPRUTE

STATE STANDARDS, REQUIREMENTS, CRITERIA, AMD LHCTATIOHS

Page 2 of 4

Standard, Requireaent,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate ts Relevant Standards

(Units Shown)

General Itaquireswnts 2-101.A Effluent discharge to awater course

Ho/Ho Sets limitations on BOD, COO,settleable solids, fecal coliforsibacteria, and pR. Ho remedialalternatives consider pointdischarge to the Rio Grande.

ethylene (TCE) 0.1 ag/LEthylbencene 0 .75 ag/LTotal xylenes 0 . 6 2 ag/LNethylene chloride 0.1 ag/LChloroform 0.1 »g/L1,1-dichloroethane 0 . 0 2 5 mg/T-ethylenedibroaide (EDB) 0 . 0 0 0 1 mg/

1.1.1-t richloro-ethane • 0 .06 wg/L

1.1.2-trichloro-ethane 0 .01 ag/L

1,1,2,2-tetra-chloroethane 0 .0 1 ag/L

Vinyl chloride 0 . 0 0 1 »g/r.PAHs: total naphtha-lene plus •onoBethyl-naphthalenes

Benzo-a-py reneChloride (Cl)Copper (Cu)Iron (Fe)Manganese (Hn)PhenolsSulfate (SO. )Total DissolvedSolids (TDS)

Zinc (Zn)PH

0 .03 ag/L0 .0007 »g/i250 sq/L1.0 ag/L1.0 ag/L0.2 ag/L0 . 0 0 5 »g,/L600 ag/L1000 ag/L10.0 ag/L

between 6 and

Page 3 of -J

TABLE 8-2DETERMINATION Of

APPLICABLE OR RELEVANT AND APPROPRIATESTATE STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

Standard, Requirement,Criteria, or Limitations Citation Description

Applicable/Relevant andAppropriate >ts

Relevant Standards(Units shown)

* Regulations for Dis-charges onto or Belowthe Surface of theGround

NEW MEXICO WATER QUALITYSTANDARDS

- General Standards

3-103.A, -B, .C

1-102

- Stream Use Designation andStandards

2-105

Discharge onto or below thesurface of the ground

No/No

Surface waters of the State No/Noof New Mexico

Discharge of a toxicpollutant to surface waters

No/No

Discharges to the main stemof the Rio Grande from theheadwaters of Elephant Butteupstream of the AngosturaDiversion work

No/Ho

No groundwater treatment orreinjection is proposed forthe Sierra Blanca site.

Designates uses for which thesurface waters of New Mexico shallbe protected and prescribes thewater quality standards necessaryto sustain the designated uses.Outlines the requirements fordischarges of toxic substances tosurface waters suitable forrecreation and support of desir-able aquatic life presently COMBOHin New Mexico waters. ARAR forpoint discharges to the Rio Grande,Sets standards for dissolvedoxygen, pH, temperature, fecalcoliform bacteria, TDS, sulfate,and chloride. No remedialalternatives consider pointdischarge to the Rio Grande.

See list on pp 1 and 2

NEW MEXICO AIR QUALITYCQmTBOL ACT- New Mexico Air QualityStandard* and Regulations

201 Discharge of participates,sulfur dioxide, hydrogensulfide, reduced sulfur,carbon monoxide, nitrogendioxide, photochemicaloxidants, and nonmethanolhydrocarbons to the air.

Mo/No Sets standards for discharges ofthese criteria to the air. ARARfor treatment effluent to the air.Such air eawissions are not a partof considered remedial alternatives.

Page 4 of 4

TABLE 8-2DETERMINATIOH OF

APPLICABLE OR RELEVANT AND APPROPRIATESTATE STANDARDS, REQUIREMENTS, CRITERIA, AND LIMITATIONS

Standard, Requirement,Criteria, or Limitation* Citation Description

Applicable/Relevant andAppropriate Co its

Relevant Standards(Wiits shown)

SEW MEXICO STATUTES, HATERLAW

Chapter 72,Article 12

Underground water statutes Ho/No Requires permits for installationof wells for consumptive use ofground water. Ho consumptive usewill occur as a result of soilremediation.

SOLID WASTE MANAGEMENTREGULATIONS (DRAFT)

Solid Waste Manage-ment (SWM) Regula-tions (Draft) , PartIII, Section 301 ,302

SWM Regulations(Draft ) , Part III,Section 304

Disposal of treatment Yes/Yesresidues

Transportation of materials Yes/Yes

Establishes procedures for opera-tion and closure of landfills fornonhaiardous materials. Opera-tion of an onsite landfill isevaluated as part of the remedy.Establish requirements for wastetransfer stations. If operationof the treatment plant requires atransfer station be built fortransportation of nonhacardousmaterials.

8 . 3 . 1 CONTAMINANT-SPECIFIC ARARS

The contaminant pathways of concern are dermal exposure to andinhalation and ingestion of contaminated soils and waste material.

Solid Waste Disposal Act

The Solid Waste Disposal Act (SWDA), as amended by the ResourceConservation and Recovery Act (RCRA) of 1976 and the Hazardousand Solid Waste Amendments (HSWA) of 1984, defines, underSubtitle C, those solid wastes which are subject to regulationsas hazardous wastes. Municipal waste and waste from theextraction, beneficiation, and processing of ores and minerals(i .e. mine waste) are specifically excluded under Subtitle C.Subtitle D requires States to develop solid waste managementplans and establish criteria to identify unsafe solid wastefacilities or practices.

Mine waste may be subject to RCRA Subtitle C requirementsto the extent that it is RCRA listed or RCRA characteristicwaste and provided that these wastes were disposed afterthe effective date of the RCRA requirement. RCRA wasteshave been identified at the Sierra Blanca site, and atleast some disposal of the mine waste was after theeffective date of the first RCRA technical requirements,i.e. November 19, 1980. Thus, RCRA Subtitle C is arelevant and appropriate requirement, especially ifremedial action is taken which constitutes treatment,storage, or disposal of these wastes (as defined by RCRA).

8 . 3 . 2 LOCATION-SPECIFIC ARARS

Physical characteristics of the site influence the type and locationof remedial responses considered for cleanup. The location-specificARARs identified for the site in Tables 8-1 and 8-2 establish

8-18

consultation procedures with Federal and State agencies and may imposeconstraints on the location of remedial measures or require mitigationmeasures.

The location-specific ARARs relate to historic preservation, fish andwildlife, wetlands, floodplains, and work in navigable waters. Thelocation-specific ARARs influence the type and location of remedialalternatives developed for the site. No location-specific ARARs havebeen identified for the Sierra Blanca site.

8 . 3 . 3 ACTION-SPECIFIC ARARS

Action-specific ARARs set controls or restrictions on particular kindsof activities related to management of hazardous substances,pollutants, or contaminants. These requirements are not triggered bythe specific chemicals present at a site but rather by the particularremedial activities that are selected to accomplish a remedy.

Potential action-specific ARARs which deal with requirements for thedegree of treatment for remediation and disposal of contaminatedgroundwater or surface water are listed in Tables 8-1 and 8-2 asneither "applicable" nor "relevant and appropriate", since siteactivities have not resulted in contaminated groundwater or surfacewater.

Solid Waste Disposal Act (SWDA1

General RCRA Requirements - The Solid Waste Disposal Actwas amended by the Resource Conservation and Recovery Act(RCRA) to control hazardous substances. The provisions ofRCRA pertinent to the Sierra Blanca site have beenpromulgated under 40 CFR Parts 257, 260, 261, 262, 264,268, and 280. EPA has determined that the aboveregulations are "applicable" to RCRA characterized andlisted hazardous wastes (40 CFR Part 260 ) , which either:

8-19

1) were disposed at a site after November 19, 1980; or 2)the CERCLA remedial action consists of treatment, storage,or disposal as defined by RCRA (40 CFR Part 264) . Inaddition, these regulations are "relevant and appropriate"to RCRA hazardous wastes disposed at a site prior toNovember 19, 1980.

Some of the contaminants of concern at the Sierra Blancasite are listed in Appendix VIII of RCRA (40 CFR Part 261,App. VIII) and the wastes were disposed on-site afterNovember 19, 1980. Therefore, the RCRA regulations aredirectly "applicable" for any future remedial actioninvolving treatment, storage, and disposal as defined byRCRA. These regulations are "relevant and appropriate" forany other activities resembling RCRA regulated activities.However, currently, "waste from the extraction,benef iciation, and processing of ores and minerals'* (40 CFRPart 261 .4 , 6, 7) is excluded from regulation under RCRA.

RCRA permits are not required for portions of CERCLAactions taken entirely on-site. Therefore, administrativeRCRA requirements ( i .e. reporting, record Keeping, etc.)are not "applicable" or "relevant and appropriate" for on-site activities. However, all hazardous wastes disposedoff-site are required by CERCLA 121 (d) (3) to be incompliance with all pertinent RCRA requirements.

RCRA Treatment Reouirements - CERCLA 121 establishes apreference for remedial actions involving treatment thatpermanently and significantly reduces the volume, toxicity,or mobility of the hazardous substances, pollutants, andcontaminants at a CERCLA site. The RCRA requirements are"applicable" at a site if: 1) the waste is hazardous; 2)the treatment complies with the RCRA definition containedin 40 CFR 260.10; and 3) the special jurisdictional

8-20

prerequisites in the pertinent subpart for each category oftreatment are satisfied. Otherwise, the RCRA requirementsare "relevant and appropriate".

RCRA Disposal Requirements - EPA has defined disposal underRCRA to be the movement (grading, excavation, etc.) of aRCRA hazardous waste originally disposed before the 1980effective date of RCRA from within a "unit area ofcontamination" and placed in another location outside the"unit area of contamination". The RCRA requirements are"applicable" to activities of this type, and "relevant andappropriate" to similar activities.

In the case of the Sierra Blanca site, as with many CERCLAsites, there is no defined RCRA type "unit", but rather an"area of contamination" with differing waste types andlevels of contamination. Therefore, excavation, treatment,and encapsulation conducted within the site would be withinthe "area of contamination" and not conform to the RCRAdefinition of disposal. The RCRA requirements are not"applicable". Any transport of wastes off-site do fallunder the definition; the RCRA requirements are"applicable" in this case. The RCRA requirements may be"relevant and appropriate" for on-site activities. Usingthe disposal requirements in this manner requires the"design and operating" RCRA requirements. These includedesign requirements for landfills (including waste pilesduring construction), surface impoundments and landtreatment units.

Land Disposal Requirements - The disposal of RCRA hazardouswaste during the course of remedial action may also besubject to the special restrictions on land disposal ofhazardous waste established by the Hazardous and SolidWaste Amendments of 1984 (HSWA). According to HSWA, all

8-21

RCRA hazardous wastes are to be reviewed by EPA todetermine if they should be banned from land disposal.Banned waste cannot be placed in or on the land unless theyhave first been treated to levels achievable by bestdemonstrated available technology (BOAT) for each hazardousconstituent in the waste.

EPA has defined placement and disposal to be identical.Whether the land restrictions are "applicable" or "relevantand appropriate*1 depend upon the disposal factorspreviously discussed. Any on-site excavation, treatment,or encapsulation of waste at the Sierra Blanca site doesnot follow the RCRA definition of disposal. Therefore,placement does not occur and the land disposal restrictionsare not "applicable", nor are they considered "relevant andappropriate" until the EPA promulgates BOAT standards forRCRA soil and debris. However, any waste transported off-site for disposal does comply with the RCRA definition; theRCRA requirements are "applicable" in this case.

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9.0 REMEDIATION ALTERNATIVES

9.1 REMEDIAL ACTION OBJECTIVES

To meet the overall objective of protecting human health and theenvironment, specific remedial action objectives are developed forcontaminants of concern (COCs) within affected media. Remedial actionobjectives are defined in this section as either the chemical specificARAR or the risk-based action level, whichever is more stringent.Based on sampling data and the Risk Assessment presented in Section6, the contaminant of concern at Sierra Blanca is lead, with minimaladditional health concerns associated with arsenic and other metals.As discussed in Section 8 . 2 , a chemical specific action level of 500ppm for lead is considered appropriate at Sierra Blanca. Only inthose areas of the site where lead levels are high are other metalsconcentrat ions aIso elevated. Thus, by approaching the s iteremediation in a manner to address those areas where lead is found atconcentrations above 500 ppm, elevated concentrations of arsenic andother metals will also be addressed.

The contaminated areas of the site consist of material piles ofpartially processed ore and tailings, tank sediments, discharge pitsediments and surficial soils. No subsurface soils or groundwaterhave been found to be contaminated, and there is no surface water onor near the site. Remediation measures will, therefore, be limitedto the distinct on-site contaminant source areas, collectivelyreferred to as the Sierra Blanca waste material.

9 . 1 . 1 CHARACTERISTICS OF CONTAMINATED MATERIAL

Based on the results of the RI, the contaminated areas at SierraBlanca are shown in Figure 9-1, and some of the characteristics ofthose areas are presented in Table 9-1. The contaminated material islocated in five material piles of partially processed ore andtailings; sediments from three discharge pits and a cinder block

9-1

PROCESSBtDG. 1INSET

-X-MPTSSS

LEGENDWASTE MATERIAL WHICH PASSED TCLPWASTE MATERIAL WHICH FAILED TCLP FOR LEADSfTE BOUNDARYORE PILETANKCONTAMINATED SOIL FIGURE 9-1

ESTIMATED EXTENT OF AREAS WITHLEAD CONCENTRATIONS GREATER THAN 500 PPM•CAMP DRESSER & McKEE INC.-

TABLE 9-1CHARACTERISTICS OF CONTAMINATED MATERIAL

Volume Arsenic LeadUnit / Sample No. fC.Y.) mg/Kg mg/Kg

MATERIAL PILESMP-01 120 52.1 18,900MP-26 53 51 .7 18,700MP-02 4 — 18,300MP-03 2 — 16,320MP-32 3 — 13,850

DISCHARGE PIT SEDIMENTSDP-01 167 7,850DP-03 128 22.3 9,050DP-04 30 79.6 5,140

SURFICIAL SOILSCBT 21 49.2 5,420SS-02 15 25.5 10,409SS-05 5 48 1 ,360

TANK SEDIMENTSTS-01TS-02TS-03TS-04TS-05TS-06TS-07

TOTAL VOL./AVG. CONC. 570 47 8,950

311122

10

1 ,5 1051 .4

1485, 160

8366.5

143

14 , 1005,5203,728

46,40012,600

9,4901 1 ,500

trench; surficial soils in two areas where contaminated runoff orspillage occurred; and fine textured sediments from seven separatetanks.

9.2 GENERAL RESPONSE ACTIONS

The general response actions identified for the Sierra Blanca sitewhich will meet the remedial action objectives, or will provide abaseline against which actions may be compared, consist of thefollowing:

No Action. This response is identified for the purposes ofestablishing a baseline with which to compare other generalresponse actions. There are no preventative or correctiveactions taken as a result of this general response action;however, monitoring of the contamination may be prescribed.

Institutional Controls. This response utilizes actionswhich control human contact with the contamination ratherthan remediating the contamination itself. These actionsmay be physical, such as fences or barriers, as well aslegal actions and zoning actions.

Containment in Place. As a genera1 response action,containment prevents risk to human health and theenvironment by restricting contact or migration of thecontaminants via soil, water, or air pathways. A number oftechnologies and different materials are available for usein establishing migration barriers. Containment in placeis distinct from general response actions which requireexcavation of the contaminated material, such as landfilldisposal.

Treatment. This action involves removal of the contaminantfrom the contaminated media, or alteration . of the

9-4

contaminant to reduce its toxicity, mobility or volume.This general response action is usually preferred unlesssite or contaminant specific characteristics make itunrealistic.

Disposal. This action involves the transfer ofcontaminated media, concentrated contaminants, or treatedmaterial to a site reserved for long-term storage of suchmaterials. Disposal sites are strictly regulated in theoperation and types of materials they may accept.

These general response actions are developed in the followingsections.

9.3 IDENTIFICATION AND SCREENING OF REMEDIAL ACTION TECHNOLOGIES

A number of potentially effective technologies are associated with thegeneral response actions selected for the site. In this Section,remedial action technologies potentially feasible for the SierraBlanca site are identified and subjected to preliminary screening,which consists of evaluation on the basis of technical feasibilityconsidering site conditions and characteristics of the waste.

The technologies considered potentially applicable to the SierraBlanca site are listed in Table 9-2. A discussion of the technologiesand process options associated with the general response actions, andthe results of preliminary screening, are presented below.

9 .3 . 1 NO ACTION

The NCP (1990) requires that No Action be evaluated as a potentialremedy for all media types. The No Action alternative serves as abaseline for comparison of other alternatives. No Action means thatno remedial activities would be conducted to remove or reduce thehazards on the site. Monitoring may be conducted, however, to

9-5

TABLE 9-2

IDENTIFICATION AND SCREENING OFREMEDIAL ACTION TECHNOLOGIES

SIERRA BLANCA SITE

Remedial Technology Process Option Scrawling Status_ — _ • —— _ ——————————————————

No Action

Institutional ControlsNoneResident RelocationAccess RestrictionsUse Restrictions

NoneTemporaryFencingDeed NoticesZoning Ordinances

Required forFeasibleFeasibleFeasibleFeasible

Consideration

Containment in Place

Treatment

Capping

Dust Control

Fixation

Extraction

Reprocessing

Biological

Thermal

All Options

Vegetative Hat

NeutralizationCement SolidificationSoil Hashing

Soil Flushing

On-Site

Off-Site

Bacterial Degradation

In-Situ VitrificationPyrolysia

Hot Feasible Without PriorConsolidation Due toNumber and Character-istics of Source Areas

Not Feasible Without PriorConsolidation Due toNumber and Character-istics of Source Areas

FeasibleFeasibleNot Feasible Du« to

Complexity andInsufficient Volume

Not Feasible Due toDispersed and ShallowSource Areas

Not Feasible Due to LowGrade and InsufficientVolume

Not Feasible Due to LowGrade and InsufficientVolume

Not Feasible at This Timefor Mining and MillingSolid Wastes

Not Feasible Due toComplexity and Cost

Not Feasible Due toComplexity and cost

TABLE 9-2IDENTIFICATION AND SCfiEEHIHG OF

REMEDIAL ACTION TECHNOLOGIESSZEIUtA BUHCA SITE

(Continued)

R»spons« Action___________B*a»di<l Technology_______Process Option_________________Screening Status

Disposal On-Site Consolidation FeasibleOff-Site RCRA Subtitle D (Municipal) Feasible

LandfillRCRA Subtitle C (Hazardous Feasible

Haste) LandfillNina Shafts Not Feasible Due to

Iaple*entationDifficulties

quantify the impacts associated with no remedial response .9.3.2

9 . 3 . 2 INSTITUTIONAL CONTROLS

Institutional controls potentially feasible for the Sierra Blanca siteconsist of access restrictions, deed notices and zoning restrictions.

Access restriction is aimed at preventing human exposure tocontaminated waste material. This option typically consists ofinstallation of signs warning of the potential hazards associated withthe site, together with barriers, such as fences, to restrict siteaccess. These measures are technically feasible.

Use restrictions would involve deed notices and zoning ordinances toregulate use of the property. Deed notices would permit notificationof potential buyers of the property about past activities at the site.Zoning would allow classification of the site to restrict permissibleuses. These measures are technically feasible.

9 . 3 . 3 CONTAINMENT IN PLACE

Containment technologies are remedies that employ a barrier to limitthe mobility of a contaminant. The containment technologiesconsidered in this section are limited to those which do not requireexcavation of the material. On-site disposal alternatives consistingof excavation, consolidation and disposal are evaluated as disposaloptions in subsequent sections.

Containment in place may consist of either capping the waste materialor providing a means of preventing the spread of windblown dust.Capping controls include clay covers (RCRA cap), soil cement covers,bituminous pavement, and soil covers. Dust controls consist of avegetative mat which is established on the waste material to preventwind erosion. For tanks, capping would consist of providing a sealedcover. Waste material at the Sierra Blanca site is located in

9-8

numerous different source areas which include waste piles, open pitsand trenches, flat expanses of surface soils, and open tanks andprocess equipment. Some of these open tanks are located withinbuildings, and capping controls would be impractical or cumbersome toimplement. Due to the number, dispersal, and individualcharacteristics of the source areas, technologies that providecontainment in place without some associated excavation andconsolidation are not considered feasible, and are eliminated fromfurther consideration. Consolidation of the material and disposal on-site is feasible, however, and is discussed in subsequent sections.

9 . 3 . 4 TREATMENT

Treatment technologies that are potentially feasible for the SierraBlanca waste material are fixation, extraction, reprocessing, andbiological and thermal techniques.

fixation

Fixation technologies applicable to mining and milling wastes includeneutralization and solidification; the latter also being referred toas physical encapsulation or immobilization. Neutralization involvesthe addition of materials with large acid neutralization capacity,such as kiln dust, which raises the pH of an acidic environment withthe accompanying fixation of metals as metallic hydroxides.Solidification consists of the fixation of contaminant metals bychemical binding and physical encapsulation from the addition ofsolidification agents, which make the contaminants unavailable tooxidation and leaching.

As discussed in Sections 4 and 7, Toxicity Characteristic LeachingProcedure (TCLP) analyses was conducted on the various types of wastematerial at Sierra Blanca, as part of the XRF program. The findingsof the TCLP analyses indicate that material piles (HP-01, HP-02, HP-03, HP-26 and HP-32) which consist of crushed ore material, and

9-9

contaminated tank sediments (TS-01 through TS-07), do leachsignificant quantities of lead when subjected to TCLP test conditions.Arsenic and barium, which were also analyzed per TCLP, are far belowregulatory limits. Notably, contaminated discharge pit sediments andcontaminated soils subjected to TCLP analyses, did not result in theleaching of any of the tested constituents above regulatory limits.This indicates that contaminated discharge pit sediments and soils atSierra Blanca will not be classified as RCRA hazardous wastes, but thetank sediments and contaminated material piles do exhibit RCRAhazardous waste characteristics with respect to leaching potential.

Based on the TCLP results, fixation processes may be applicable tocontaminated material piles and tank sediment at Sierra Blanca, butmay not be necessary for the contaminated soils and discharge pitsediments.

Neutra1i z at ion

Neutralization of acid formation in the waste material, which resultsin inhibition of contaminant mobility, can be achieved through theaddition of sodium compounds, such as soda ash, or calcium containingmaterials, such as lime, cement kiln dust, or fly ash.

To determine if neutralization is a feasible response action,neutralization bench scale testing is currently being performed onrepresentative samples of the waste material. The results of thebench scale testing are to be presented as an addendum or supplementalreport. At this time, it is assumed that neutralization is a viabletreatment alternative, and this technology is retained for furtherevaluation.

Solidification

Several processes have been developed to immobilize metals in soilsby solidification. These involve mixing the contaminated soils with

9-10

cement or proprietary chemicals to solidify the mass and preventleaching of metals. In addition to Portland cement, solidificationagents include thermoplastics and organic polymers. Many of thesetreatments are combined with acid neutralization, which willimmobilize the metals through conversion to insoluble carbonate andhydroxide forms, as well as encase them in a solidified mass.

Pilot testing of solidification treatment methods are required todetermine the feasibility of this response action. If the solidifiedmaterial passes the toxicity characteristic leaching procedure (TCLP)test, then treatment is successful and the material is suitable forunclassified disposal. To assess the feasibility of solidificationas a treatment option, bench scale tests are being performed onrepresentative samples of the Sierra Blanca waste material. Since thevolume of the waste material potentially requiring solidification iscomparatively small (225 cy), the use of a proprietary solidificationprocess is not cost effective. Based on interviews withrepresentative vendors, it appears that 8 , 0 0 0 to 10 ,000 cubic yardsof material are necessary to warrant mobilization of proprietaryfixation treatment process equipment. For this reason, bench scaletesting of solidification treatment is limited to Portland cement ofvarious mix compositions.

The results of the bench scale testing will be presented as anaddendum or supplemental report. Since cement solidification isfeasible, this technology is retained for further evaluation.

Extraction

Extraction process options for Sierra Blanca waste material includesoil washing and soil flushing. Both remove leachable and/orextractable contaminants from the soil matrix. The ability of theseprocesses to lower the concentrations of metals depends on thecharacteristics of the waste material and the contaminants.Contaminants which are incorporated into the soil matrix are not

9-11

readily available for extraction processes. For example, leadcontamination in tailings from mining and milling operations iscommonly incorporated into crystal matrices, which would also be thecase for unprocessed ores. Without other physical treatment, only theamorphous form of the metals may be recovered. Since this is also theform that would leach from contaminated soils, removal of thisfraction would be protective of human health and the environment.Extraction processes may, therefore, be feasible for the material pileand tank sediment materials that failed the TCLP test.

Soil Washing

Soil washing would involve the addition of acidic or chelating agentsto excavated waste material to bind the metal contaminants. Thephysical process of mixing usually occurs in mobile units and helpsto distribute the chemicals, enhance binding, and remove the chemical-metal complex from the soil. The washed material together with liquidcontaminated with chemical-metal complexes are then separated from thesolution by pH dependent treatment processes, depending on thechemical agent used. Following dewatering of the metal complexes, asludge exists for disposal as hazardous waste. The liquid may beregenerated for further use or disposal to a Publicly Owned TreatmentWorks (POTW).

Soil washing would be feasible to implement although equipmentrequirements are substantial. Equipment requirements for a soilwashing process would include a screen, chemical storage and feedingequipment, mixing tanks, clarifier, and dewatering equipment. Waterseparated from the process could be discharged to the Carrizozo POTW,and dewatered sludge containing the metal complexes would betransported to a hazardous waste landfill. The equipment requirementsfor soil washing are greater than other feasible soil treatmentprocesses, such as fixation. This process also suffers from thedisadvantage that a separate liquid waste stream is created. Also,the effectiveness of soil washing as a treatment option cannot be

9-12

properly evaluated without bench and pilot scale tests. Due to therelatively small volume of material present at the Sierra Blanca site,and the complexity associated with a soil washing process and likelyhigh costs, this technology is eliminated from further consideration.

Soil Flushing

Soil flushing uses the same processes as soil washing for chemicalbinding, treatment of the contaminated liquid, and separation of themetal complexes from the liquid. It is an in-situ process, anddiffers from soil washing in that the mixing process occurs throughinjection of the washing solution directly into the unexcavatedmaterial, rather than in mobile units or tanks. Removal of the liquidwith complexed metals is then accomplished through the use ofextraction wells and infiltration galleries. The advantage of thisoption is that excavation of the material is not required.

For the Sierra Blanca site, the waste material is located in numerousdifferent source areas, some of which are in the form of above gradematerial piles or tanks which contain contaminated sediments. Soilflushing process options would not be feasible for the above groundmaterial. The remaining waste material is characterized by relativelythin layers of surficial soils. Given the shallow depths(approximately two feet), and the fact that this material is notcontiguous, installation and operation of injection and extractionwells would not be practical. For these reasons, soil flushingprocess options are eliminated from further consideration.

Reprocessing

Reprocessing wastes to extract recoverable metals, and render thewaste non-hazardous in the process, is a response action that has beenevaluated for other EPA Superfund sites involving mining and milling

9-13

wastes. This remedial technology generally consists of establishinga milling process on-site or transporting the wastes to an operatingfacility. Processes normally considered include pyrometallurgical(smelting process) or hydrometallurgical (chemical leaching or frothflotation process).

For the Sierra Blanca site, there is insufficient volume of wastematerial to consider implementation of an on-site reprocessing option.For off-site reprocessing, the only waste material which would bepotentially suitable would be the material piles and perhaps some ofthe tank sediments. These materials contain a metals contentsufficiently high to possibly make them acceptable to a smeltingfacility. The contaminated surficial soils and discharge pitsediments have generally low level metals contamination and, ifexcavated, would contain impurities such as organic matter and debris.This material would not be acceptable to existing smelting or metalsrefining facilities for reprocessing. Although the material piles andtank sediments comprise only about 225 cubic yards of material, thistechnology is attractive since it may be very simple to implement.Additionally, this response action could work well in conjunction withanother remedial technology for the discharge pit sediments andsurficial soils.

To investigate the feasibility of off-site reprocessing of the oresand tank sediments, a survey of metals smelting and refiningfacilities was conducted. The operations manager of the nearestoperating lead smelter to the site was contacted to discuss thereprocessing option. After having a sample of the Sierra Blanca wastematerial assayed for precious metals and lead content, the operationsmanager determined that he was not interested in accepting thematerial for reprocessing.

Biological

Biological treatment technologies are commonly applied to treatment9-14

of organic contaminants. For inorganic contaminants, biologicalmethods have been used in wetlands treatment systems for acid drainagefrom tailings piles and to remove metals. For the metalscontamination in the ores, tank sediments, and surficial soils at theSierra Blanca site, biological treatment would have a very limitedpotential. One recently developed technology involves seeding thewaste material with special surfactants which inhibit the growth ofiron bacteria, the metal/pyrite oxidizers which create acids. This,in turn, enhances the growth of sulfate reducing bacteria whichconverts acids back into pyrite materials.

In this treatment method, the material is consolidated, graded, andseeded with the surfactants in capsules which provide a timed releaseover an approximate three-year period, and which should be effectivein reducing iron bacteria for seven years. After seven years,revegetation can start acting as a control on the recurrence of thebacteria by inducing genesis of a normal soil that naturally controlsthe iron bacteria. This occurs through the generation of naturalorganic acids and the presence of beneficial heterotrophic bacteriathat compete for nutrients with the iron bacteria.

While promising, biological treatment of tailings and soils withmetals contamination has not been proven in full-scale applications.Thus, the long-term effectiveness of this technology is unknown. Dueto the many uncertainties currently associated with this technology,and the small volume of waste to be treated, biological treatment ofSierra Blanca wastes is eliminated from further consideration.

Thermal

Thermal treatment process options applicable to tailings and surf icialsoils with metal contamination are in-situ vitrification andpyrolysis. In-situ vitrification is a thermal treatment process thatconverts contaminated solid material into a chemically inert andstable crystalline product. It is a technology that is potentially

9-15

applicable to immobilize contaminants in the waste material at thesite. Pyrolysis utilizes extremely high temperatures in the absenceof oxygen to dissociate wastes into their component atoms. Coolingresults in recoverable streams of metals, siliceous materials, andgases. This process option is technically feasible for the metalscontaminated waste material on the site.

Both the in-situ vitrification and the pyrolysis process would bedifficult to implement for treatment of Sierra Blanca wastes. Bothprocesses are complex to construct and operate, both have extensiveequipment requirements, and both would produce gas sidestreams whichwould require further treatment. Additionally, the availability ofservices, equipment, and skilled workers for these processes islimited. Costs to implement either option would be very high comparedto other feasible treatment technologies. For these reasons, neitherin-situ vitrification nor pyrolysis are feasible, thus thermaltreatment of Sierra Blanca wastes is eliminated from furtherconsideration.

9 . 3 . 5 DISPOSAL

Disposal technologies potentially feasible for the Sierra Blanca wastematerial include consolidation and disposal on-site, excavation andremoval to an off-site municipal or hazardous waste landfill, orexcavation and disposal in an abandoned mine shaft. These disposaloptions may be implemented in association with fixation andreprocessing options previously discussed.

On-Site

Whereas containing the wastes in place by capping, vegetative mats,or other means is not feasible due to the number and character ofindividual source areas on the site, consolidating the wastes in acentral on-site location would be feasible in conjunction withsuitable controls to prevent the spread of contamination. Disposal

9-16

of the Material on-site would be protective of human health and theenvironment with a properly designed containment cap over the pile,or with fixation processes to address leachable materials.

Given the characteristics and climate of the Sierra Blanca site, anappropriate disposal location could consist of an unlined cell witha soil cover, and monitoring wells. This design would preventintrusion of surface water into the fill, and allow for periodicmonitoring of the groundwater at the site.

If the wastes which have been found to be characteristically hazardousby the TCLP tests are not treatable by fixation or reprocessing, thena RCRA Subtitle C-compliant landfill, or RCRA vault, would be relevantand or appropriate, unless a variance to the Land Ban (40 CFR Part268) regulations were granted by EPA and the State of New Mexico.This landfill would have a double liner, leachate collection system,impermeable cap, surface water run-on/run-off controls, andgroundwater monitoring system. Due to the extensive construction andoperational standards associated with these facilities, the relativelylow volume of contaminated material present, and the availability ofother RCRA Subtitle C-compliant hazardous waste landfills withinreasonable distances, construction of an on-site RCRA vault for SierraBlanca wastes is not considered feasible, and is eliminated fromfurther consideration. However, construction of a RCRA Subtitle D-compliant landfill is feasible and is retained for furtherconsideration.

Off-site

The off-site disposal options for Sierra Blanca waste materials aremunicipal or hazardous waste landfills or abandoned mine shafts.

Municipal Landfill

The wastes may be disposed of in a municipal landfill if they are not9-17

characteristically hazardous. However, the municipal landfill mustalso be willing to accept the waste. Several landfill operators inthe vicinity of the site were contacted to determine if the sierraBlanca wastes are suitable for disposal in their facility. Eventhough much of the waste has been determined to be non-hazardous, perTCLP, and other wastes may be treatable by fixation processes priorto disposal, some operators are unwilling to accept Superfund wastesin their municipal landfills. Other operators, however, would bewilling to accept the waste provided it was certified as non-hazardous, and provided this method of disposal is acceptable to theState of New Mexico and EPA. Municipal landfill disposal, therefore,appears to be feasible and is retained for further evaluation.

Hazardous Waste Landfill

Characteristically hazardous wastes must be disposed of in a hazardouswaste landfill, unless a variance to RCRA regulations is given to thewastes by EPA and the State of New Mexico. The closest Suitablepermitted hazardous waste landfills that would accept the wastes arelocated in Nevada, Utah, and Colorado. Given the availability ofthese facilities within reasonable transportation distance from theSierra Blanca site, this disposal option is retained for furtherevaluation.

Abandoned Mine

Another possible disposal option consists of excavating the wastematerial and disposing of it in an abandoned mine in the vicinity ofthe site. An initial criterion for the acceptability of a potentialmine disposal site is that the proposed repository should be aboveseasonal high groundwater levels in the mine to prevent thepossibility of leaching.

To assess the feasibility of this approach, the New Mexico AbandonedMine Lands Bureau was contacted, as this agency would have regulatory

9-18

authority over any potential mine disposal site. After consideringthis method of disposal, the Abandoned Mines Bureau determined thatthey would not be able to accept Superfund wastes at their abandonedmines sites. Disposal of Sierra Blanca waste material in an abandonedmine is therefore eliminated from further consideration.

9.4 CRITERIA FOR ALTERNATIVES DEVELOPMENT

In evaluating and screening technologies, the process optionsassociated with the technology types determined to be potentiallyfeasible are evaluated and screened in terms of relativeeffectiveness, implementability, and cost. Primary emphasis of theevaluation is placed on effectiveness in protecting human health andthe environment; however, implementability and cost evaluations arealso important. Each of these three evaluation criteria are describedbriefly below.

EffectivenessSpecific process options that have been identified shouldbe evaluated with respect to their effectiveness relativeto other process options within the same technology type.This evaluation should focus on the following (U.S . EPA,1988) :1) The potential effectiveness of process options inhandling the estimated areas or volumes of media andmeeting the contaminant reduction goals identified inthe general response actions;2) The effectiveness of the process options in protectionof human health and the environment during theconstruction and implementation phase; and3) How proven and reliable the process is with respect to

the contaminants and conditions at the site

Implementabi1itvImplementability encompasses both the technical andinstitutional feasibility of implementing a technologyprocess. Technical implementability is used as an initial

9-19

screen of technology types and process options to eliminatethose that are clearly ineffective or unworkable at thesite. Therefore, this subsequent, more detailed evaluationof the process options places greater emphasis on theinstitutional aspects of implementability, such as theability to obtain necessary permits for off -site actions,the availability of treatment, storage, and disposalservices (including capacity), and the availability ofnecessary equipment and skilled workers to implement thetechnology.

costCost plays a limited role in the screening of processoptions. Relative capital and operations and maintenance(O&M) costs are used rather than detailed estimates at thisstage in the process. The cost analysis is based onengineering judgment, and each process is evaluated as towhether costs are high, low, or medium relative to otherprocess options in the same technology type that achievethe same degree of protectiveness.

Screening of the feasible technology process options on the abovebasis is conducted in order to identify processes representative ofthe particular response action. This screening process isillustrated in Table 9-3.

9.5 DEVELOPMENT OF REMEDIATION ALTERNATIVES

In developing remediation alternatives for the Sierra Blanca Site,general response actions were combined using technologies developedand summarized in Table 9-3. The Alternatives considered feasible andsuitable for continued evaluation are described below.

Although No Action does not achieve the remedial action objectives,this alternative is required for consideration. No action, while notinvolving remediation of the waste material, will require some levelof cost to implement which are evaluated in Section 10.

Of the Institutional Controls available, only access, land use, anddeed notices are considered appropriate. These restrictions will be

9-20

TA3LE 9-3SIERRA 8LANCA SITE

EVALUATION OP FEASIBLE REMEDIATION TECHNOLOGIES

ResponseAction

RemedialTechnology

ProcessOption Effectiveness Implementafaility Cost

Ho Action Nona None Does not achieve r«objectives

tdial action Requires administrative,legal, and regulatoryefforts

None

Institutional Resident Temporary Would reduce exposure threatControls relocation during remediation; would not be

necessary with appropriate con-trols during Material excavation

Permanent Would remove exposure threat tonearby residents; would notreduce contamination

Access Fencing Would •ininize exposure threatsRestrictions by limiting accessUse Deed Notices Depends on intensity of futureRestrictions enforcement; would not reduce

potential exposure risksZoning Latitude allowed by regulationsOrdinances may limit effectiveness; would

not reduce potential exposurerisks

Few residents torelocate; may belocally unpopular

Few residents torelocate; may belocally unpopularReadily implementable

Readily implementable

Readily implementable

Low capital,no out

Moderate capital,no OUf

Low capital,low outNegligible

Negligible

Treatment Fixation

Disposal

Reprocessing

Oo-Site

Off-Site

Neutralization

Solidification

off-Site

RCRA Subtitle DLandfill

RCRA Subtitle D(Municipal)LandfillRCRA Subtitle C(HazardousWatte) Landfill

Effective in reducing toxicityand mobility of contaminants

Effective in reducing toxicityand mobility of contaminantseffective in rendering wastesnon-hazardous and in recoveringmetals; not effective forsurficial soilsEffective in reducing mobilityof contaminants

Effective in reducing mobilityof contaminants

Effective in reducing mobilityof contaminants

Readily implementable;would require crushingof oresReadily implementable

Readily implementablefor ores and tanksediments

Xmplementable if wastesare not characteristi-cally hazardousXmplementable if wastesare not characteristi-cally hazardousReadily implementable

Moderate capital,low O&M

Moderate capital,low O&MLow capital,no out

Moderate capital,moderate OfcM

Moderate capital,no out

High capital,no 0(M

relatively simple to implement, as zoning regulations already existin Carrizozo, and adding access controls and deed notices should notbe difficult. Relocation of residents, either on a temporary orpermanent basis, should not be necessary, as adequate measures can beprovided to protect nearby residents during site remediationactivities.

Feasible treatment alternatives for this site are limited, and onlysolidification fixation using Portland cement or similar compoundsappears feasible at this time. Results of bench scale tests onneutralization processes, currently underway, may also demonstrate thesuitability of this approach. Both neutralization and solidificationrequire similar remediation activities, and are expected to providea similar level of treatment at similar costs. Thus, for the purposeof development and detailed evaluation of alternatives, only one ofthese treatment methods is evaluated. Cement solidification isselected for more detailed evaluation; chemical neutralization willnot be further considered unless the bench scale test results indicatethat greater treatment efficiency or equivalent treatment efficiencyand cost advantages are possible using this technology.

Disposal alternatives include on-site disposal in an RCRA Subtitle D-compliant landfill, which would require treatment of the leachablematerial (material piles and tank sediments) prior to disposal. Off-site disposal in a municipal landfill would be feasible provided theleachable material is first treated. Otherwise, the material wouldrequire disposal in a hazardous waste landfill.

Considering the above requirements, the feasible treatment anddisposal technologies are combined into Alternatives 3, 4, and 5, asshown on Table 9-4. These alternatives are evaluated in detail inSection 10.

9-22

TABLE 9-4SIERRA BLANCA SITE

REMEDIATION ALTERNATIVES

Alternative Description

No Action

2. Institutional Controls3. Cement Solidification / On-Site

Disposal

Cement Solidification / Off-SiteMunicipal Landfill Disposal

Off-Site Municipal and HazardousWaste Landfill Disposal

No action to reduce the toxicity, mobility,or volume of contaminantsAccess, land use, and deed restrictionsExcavate contaminated material; treatteachable material piles and tanksediments by cement solidification;dispose on-siteExcavate contaminated material; treatteachable material piles and tanksediments by cement solidification;transport to and dispose in municipallandfillExcavate teachable material piles andtank sediments; transport to a permittedhazardous waste disposal facility.Excavate non-leachable surficial soilsand discharge pits; transport to anddispose in municipal landfill

10 .0 DETAILED EVALUATION OF ALTERNATIVES

A total of five alternatives for the sierra Blanca site remediationare analyzed in detail in this section. The alternatives that areevaluated consist of the following:

Alternative 1 - No ActionAlternative 2 - Institutional ControlsAlternative 3 - Cement Solidification/On-Site Landfill

DisposalAlternative 4 - Cement Solidification/Off-Site Municipal

Landfill DisposalAlternative 5 - Off-Site Municipal and Hazardous Waste

Landfill Disposal

10 . 1 EVALUATION CRITERIA

Each of the above alternatives are described in this Section byproviding the following information, as appropriate:

Detailed description of remediation activitiesTreatment schematicSize and configuration of remediation componentsTreatment ratesSpace requirementsSite layoutOn-site and off-site activitiesRequired permitsTime frame required to achieve remediation goalsDetailed capital and O&M costsPresent worth of remediation costs

The detailed evaluation process is a structured format, designed toprovide relevant information needed to adequately compare and evaluate

10-1

feasible alternatives to allow selection of an appropriate remedy forthe site by EPA through the Record of Decision (ROD) process. Theremedy must meet the following statutory requirements:

Be protective of human health and the environment;

Attain ARARs (or provide grounds for invoking a waiver);

Utilize permanent solutions and alternative treatmenttechnologies or resource recovery technologies to themaximum extent practicable;

Satisfy the preference for treatment that reduces toxicity,mobility, or volume as a principal element, or provide anexplanation in the ROD as to why it does not; and

Be cost effective.

Nine evaluation criteria have been developed by EPA to address thestatutory requirements listed above and to address additionaltechnical and policy considerations that have proven to be importantfor selecting remedial alternatives. These criteria are listed andbriefly described below:

Overall Protection of Human Health and the Environment -How well the alternative reduces risks to human health andthe environment, through treatment, engineering orinstitutional controls.

Compliance with ARARs - How well the alternative complieswith all applicable or relevant and appropriaterequirements or, if a wa iver is required, how it isjustified.

Long-Term Effectiveness and Permanence - How well the10-2

alternative maintains long-term effectiveness in protectionof human health and the environment. Alternatives whichafford the highest degree of long-term effectiveness andpermanence are those that leave little or no waste at thesite.

Reduction of Toxicity, Mobility, or Volume throughTreatment - Anticipate performance of the specifictreatment technologies that an alternative may employ andtheir ability to destroy or irreversibly treatcontaminants.

Short-Term Effectiveness - How well the alternativeprotects human health and the environment duringconstruction and implementation of a remedy.

Implementability - Whether or not the alternative istechnically and administratively feasible, and whether ornot the required goods and services are available.

Cost - Analysis of capital and O&H costs of eachalternative to determine cost-effective remedies. Costestimates are developed with relative accuracy (-30 to+50%) and are presented as present worth costs so thatalternatives can be reasonably compared.

State Acceptance - To be completed for the most part afterthe public comment period; this criterion describes thepreference of the State or support agency.

Community Acceptance - To be completed for the most partafter the public comment period; this criterion reflectsthe preferences of the community.

Each of the five alternatives for Sierra Blanca contamination are10-3

individually evaluated then comparatively analyzed on the basis of thefirst seven of the nine criteria above. The last two criteria (Stateand community acceptance) will be fully addressed in the Record ofDecision (ROD) after the public comment period.

10 .2 ALTERNATIVE 1: NO ACTION

10 .2 . 1 DESCRIPTION

The No Action alternative (Alternative l) provides a baseline forcomparing other remedial alternatives for the Sierra Blanca site.Because no remedial activities would be implemented to mitigatecontamination present at the site under this alternative, long-termhuman health and environmental risks for the site are as presented inthe baseline risk assessment in Section 6. Although Alternative 1does not include any remediation of contamination, it would consistof continued periodic monitoring of groundwater quality so that humanhealth and environmental risks posed by site contaminants could be re-evaluated on a periodic basis.

1 0 . 2 . 2 CRITERIA ASSESSMENT

Alternative 1 is implementable; however, it provides no treatment,engineering, or institutional measures to control the exposure ofreceptors to contaminated material. No reduction in risks to humanhealth and the environment would occur.

No controls for exposure, other than the existing fence, and no long-term or short-term site management are included under Alternative 1.This alternative provides no reduction in the toxicity, mobility, orvolume of the contaminated ores, tank sediments, and surficial soilson the site. All existing and potential future risks associated withthe site would remain. With respect to groundwater, no effects fromsite contaminants have been detected. With respect to soils,quantifiable risks are present which consist of hazards arising from

10-4

potential exposure to lead, with limited additional effects from othermetals (Section 6).

Alternative 1 would not provide any increased protection to humanhealth or the environment, and it would not be in compliance withARARs due to requirements imposed by RCRA Subtitles C and D regardingdisposal of mining wastes, and due to New Mexico solid wasteregulations.

1 0 . 2 . 3 COST ESTIMATE

Although Alternative 1 is to provide no action, some expenditure ofcapital costs would be required. These would be for installation oftwo additional monitoring wells on the site. These wells would berequired together with the existing wells to allow proper long-termmonitoring of the groundwater which flows away from the site.Indirect capital costs are also required for engineering and designof the monitoring well installation, contingency funds,mobilization/demobilization costs, and associated legal and regulatorycosts. These indirect capital costs are included as an estimatedpercentage of the direct capital costs in all of the remediationalternative cost estimates.

Annual operation and maintenance (O&M) costs would include semi-annualgroundwater sampling and analysis for TAL metals for an estimated 30-year period. Indirect O&M costs include administration costs and amaintenance reserve and contingency fund.

The estimated present worth cost for Alternative 1 is $48 ,000 and isdetailed in Table 10-1. The present worth cost is based on an assumedlife of 30 years and an annual interest rate of 9 percent.

10-5

I...

TABLE 10-1ALTERNATIVE!: NO ACTION

PRELIMINARY COST ESTIMATE

Description: Periodic ground water monitoringInterest Rate: 9%Level of Accuracy: +50% to -30%DIRECT CAPITAL COSTS

COSTCOMPONENT UNIT QUANTITY

UNITCOST

CAPITALCOST

Install Additional Monitoring Wells EachTOTAL DIRECT CAPITAL COSTSINDIRECT CAPITAL COSTS1. Engineering & Design (15%)2. Contingency (25%)3. Other Indirect Costs

a. Legal (5%)b. Regulatory (5%)c. Mobilization/Demobilization (20%)

TOTAL INDIRECT CAPITAL COSTSTOTAL CAPITAL COSTS (DIRECT + INDIRECT)

$5,000 il&QQQ$10,000

$1,5002,500

500500

J2J1QQSLflQQ

$17,000

TABLE 10-1ALTERNATIVES NO ACTION

PRELIMINARY COST ESTIMATE(Continued)

DIRECT ANNUAL COSTS

COSTCOMPONENT UNIT

QUANTITYFREQUENCY (PER YR)

1. Ground Water Sampling/Analysis Ea Semi-annual

TOTAL DIRECT ANNUAL COSTSTOTAL PRESENT WORTH OF DIRECT ANNUAL COSTS

INDIRECT ANNUAL COSTS1. Administration2. Maintenance Reserve &

ContingencyEaEa

AnnualAnnual

TOTAL PRESENT WORTH OF INDIRECT ANNUAL COSTSTOTAL PRESENT WORTH (CAPITAL + ANNUAL) COSTS

UNITCOST$1 ,000

--

DIRECTANNUALCOST LIFE$2,000 30

$2.000

$ 500 30500 30

PRESENTWORTHCOSTS

$ 20.500

$ 20,500

$ 5,1005.100

$10,000£48.000

10 .3 ALTERNATIVE 2! INSTITUTIONAL CONTROLS

10 .3 . 1 DESCRIPTION

Alternative 2 consists solely of institutional control measuresdesigned to isolate receptors from site-based risks. Under thisalternative, no actual remedial measures to directly address thecontaminated material on the site are implemented; rather, legalcontrols, such as land use and access restrictions, are employed tominimize the likelihood of receptor contact with contaminated media.Continued monitoring of groundwater as described for Alternative 1 isalso included as a part of Alternative 2 to ensure that the risks tohuman health are being addressed by the institutional controls.

Institutional controls considered feasible for the Sierra Blanca siteare access and land use restrictions. Access would be restricted byprovision of new site fencing to replace the existing barbed wirefence, plus appropriate signage to warn of the hazards on the site.Land use restrictions would consist of altering the zoning inaccordance with the existing City of Carrizozo zoning ordinance tolimit permissible uses of the site. Deed notices would consist ofrecording an appropriate notice with the County of Lincoln to alertparties interested in the property of the hazards contained on thesite. These restrictive measures may also be included as elements ofother remediation alternatives.

1 0 . 3 . 2 CRITERIA ASSESSMENT

The use of institutional control measures provides a greater degreeof protection of human health than the No Action alternative alone,since institutional actions can reduce the potential exposure ofreceptors. Access and land use restrictions further limit activitieson the property which would minimize exposure risks. While somedegree of human health protect iveness would be provided by Alternative2, it would not be protective of the environment since the

10-8

contamination would remain.

Like Alternative l, Alternative 2 would not comply with ARARs due torequirements imposed by RCRA Subtitles C and D regarding disposal ofmining wastes, and due to New Mexico solid waste regulations.Although reduction in the potential for human exposure would berecognized under this alternative, only limited long-termeffectiveness would be provided due to difficulties in enforcement.Additionally, this alternative provides no reduction in the toxicity,mobility, or volume of contaminants at the site. Alternative 2 mayalso be difficult to implement, since it may be unacceptable to theState of New Mexico and to the residents of Carrizozo.

1 0 . 3 . 3 COST ESTIMATE

Capital expenditures under this alternative include costs for warningsigns and additional fencing, and administrative costs for deednotices and zoning restrictions. Additionally, as continuedgroundwater monitoring is a component of this alternative, theinstallation of two additional monitoring wells is included. Indirectcapital cost items include engineering and design, contingencies,legal, regulatory, and mobilization/demobilization.

Annual costs associated with this remedial action are associated withsemi-annual groundwater sampling. Indirect annual costs includeadministration, contingency, and maintenance reserve.

The present worth cost estimate for Alternative 2 is $ 1 19 ,000 asdetailed in Table 10-2. The present worth cost is based on a life of30 years and an annual interest rate of 9 percent.

10-9

TABLE 10-2ALTERNATIVE 2: INSTITUTIONAL CONTROLS

PRELIMINARY COST ESTIMATE

Description: Access and land use restrictionsInterest Rate: 9%Level of Accuracy: +50% to -30%DIRECT CAPITAL COSTS

1.2.

3.

COSTCOMPONENT

Access Restrictiona. Fencing & SignsLand Use Restrictionsa. Deed Noticesb. Zoning RestrictionInstall Additional Monitoring Wells

UNIT

L.F.L.S.L.S.Ea

QUANTITY

2,510112

UNITCOST

$121,0001,0005.000

CAPITALCOST

$30,0001,0001,000

1Q.QQQTOTAL DIRECT CAPITAL COSTSINDIRECT CAPITAL COSTS1. Engineering & Design (7%)2. Contingency (15%)3. Other Indirect Costsa. Legal (5%)b. Regulatory (5%)c. Mobilization/Demobilization (10%)TOTAL INDIRECT CAPITAL COSTSTOTAL CAPITAL COSTS (DIRECT + INDIRECT)

$42,000

$2,9006,3002,8002.8005.500

S2Q.QQQ

$62,000

TABLE 10-2ALTERNATIVE 2: INSTITUTIONAL CONTROLS

PRELIMINARY COST ESTIMATE(Continued)

DIRECT ANNUAL COSTS

1 .

COSTCOMPONENT

Ground Water Sampling/AnalysisUNITEa

FREQUENCYSemi-annual

QUANTITY(PER YR)

2

UNITCOST

$1,000

DIRECTANNUALCOST

$2,000LIFE30

PRESENTWORTHCOSTS

$20.500

TOTAL DIRECT ANNUAL COSTSTOTAL PRESENT WORTH OF DIRECT ANNUAL COSTSINDIRECT ANNUAL COSTS

$2,000

1. Administration2. Maintenance Reserve &Contingency

EaEa AnnualAnnual

$ 500500

3030

TOTAL PRESENT WORTH OF INDIRECT ANNUAL COSTSTOTAL PRESENT WORTH (CAPITAL + ANNUAL) COSTS

$20,500

$ 5,1005.100

$10,000S93.000

10 .4 ALTERNATIVE 3: CEMENT SOLIDIFICATION/QN-SITE DISPOSAL

10 .4 . 1 DESCRIPTION

Alternative 3 involves treatment of the contaminated waste materialon the Sierra Blanca site, followed by on-site disposal. Treatmentwould be accomplished by a fixation process using Portland cement tosolidify the waste material. Non-leachable wastes (as per TCLPresults) present on the site would not require treatment. Aftertreatment, both wastes types would be disposed in an on-site landfill.A schematic of Alternative 3 is shown on Figure 10-1.

As discussed in Section 9, fixation is the only suitable treatmenttechnology that is feasible for the wastes, and the cementsolidification process appears to be the most appropriate fixationprocess. Results of ongoing bench scale studies of both Portlandcement solidification and chemical neutralization fixation processeswill likely confirm this assumption; however, in the event thatneutralization is found to be more effective, neutralization would beimplemented in lieu of cement solidification.

Treatment of Sierra Blanca waste material is applicable to only theleachable fraction, i .e. , that portion of the waste which did not passthe TCLP tests, and which therefore would be expected to leach leadto the environment. The wastes which failed the TCLP tests are thematerial piles and the tank sediments. Contaminated surficial soilsand soils within the discharge pits successfully passed the TCLP tests(although they remain hazardous due to other potential receptorexposure pathways besides leaching, such as ingestion). This non-leachable fraction, thus, does not require further treatment; however,the non-leachable wastes must be disposed in an acceptable manner.Minimum standards for land disposal of the non-leachable wastes areconsidered to be those contained in RCRA Subtitle D. After fixationtreatment, the leachable wastes will be rendered non-leachable, andmay then also be disposed in accordance with RCRA Subtitle D

10-12

t I

SUPPLEMENTALSAND/AGGREGATE

CEMENT

WATER

EXCAVATE LEACHABLECONTAMINATED MATERIAL

ORE PILES

TANK SEDIMENTS

-\_V\vM\uT\\\\u

RCRA SUBTTTLELANDFILL(ON-SITE/

EXCAVATE NO

CONCRETE BATCHPLANT

CONTAMINATED MATERIAL

DISCHARGE PITS

CONTAMINATEDSURFICIAL SOILS

FIGURE 10-1CEMEMT SOUDIFICATION FIXATION TREATMENT SCHEMATIC

CAMP DRESSER i McKEE INC.

(municipal and industrial solid waste) standards. A summary of boththe leachable and non-leachable contaminated material quantities onthe Sierra Blanca site are provided on Table 10-3.

Final disposal of the treated wastes (leachable fraction) and theuntreated wastes (non-leachable fraction) under Alternative 3 wouldbe on-site. Construction standards for the on-site landfill would bedetermined during the remedial design phase prior to implementation,and would be developed in accordance with Federal and State ARARs.

RCRA Subtitle D-compliant landfills are designed on a site-specificbasis, and for this site it is assumed that appropriate controls wouldbe provided by a simple subgrade, waste material repository, and soilcap. No impermeable liner in the landfill should be necessary as thetreated waste material would be non-leachable, and the landfill couldbe constructed well above seasonal high groundwater levels.Additionally, application of the Hydrologic Evaluation for LandfillPerformance (HELP) computer model (Section 2 .5 . 1 ) predicts minimalpercolation of precipitation to groundwater at the site. The landfillcap would consist of a layer of topsoil to prevent access to thecontaminated material within the landfill. The cap will be graded topromote runoff of stormwater, and external storm water controls, suchas drainage swales, would be constructed to keep storm water away fromthe landfill. Monitoring wells would also be provided around thelandfill to verify that leaching of contaminants is not occurringbased on periodic sampling. A representative section for a RCRASubtitle D-compliant landfill considered appropriate for the SierraBlanca site is depicted on Figure 10-2.

Implementation of Alternative 3 would consist of leasing a standardportable concrete mixer and setting it up on the site. Portlandcement of a type to be determined based on bench scale tests would bepurchased and stockpiled on-site, together with any supplemental sandor aggregate required to achieve the mix design. The contaminatedmaterial piles and tank sediments would be excavated and discharged

10-14

J

TABLE 10-3SIERRA BLANCA SITE

CONTAMINATED WASTE MATERIAL QUANTITIES

Est. Vol. EstimatedSource Area_____ fC.Y.^ S.G. Mass m

1. LEACHABLE MATERIAL*Material Piles 182 3.00 460Tank Sediments** 43 2.65 96Subtotal 225 556

2. NON-LEACHABLE MATERIAL*Discharge Pits and 345 2.65 770Surficial Soils

TOTAL 570 1,326

* Per TCLP test (see Section 4.6)** Includes cinder block trench sedimentsC.Y. = cubic yardS.G. = specific gravityT = ton

WIN.)EXISTINGGRADE EXISTING GRADE

SOIL COVER

TREATED (SOLIDIFIED)WASTE MATERIAL

NON-LEACHABLE UNTREATEDWASTE MATERIAL

MONITORINGWELL (TYP.)MONITORINGWELL (TYP.)

NOTE: THIS CROSS-SECTION ILLUSTRATES THEALTERNATIVE 3 ON-SITE DISPOSAL AREAIN DISCHARGE PIT 1.

FIGURE 10-2ON-SfTE LANDFILL

REPRESENTATIVE SECTIONCAMP DRESSER & McKEE INC.

into the cement mixer where the material would be mixed with Portlandcement, water, and any supplemental sand or aggregate required. Theresulting concrete mixture would then be deposited in the on-sitelandfill (Discharge Pit l). Non-leachable contaminated surficialsoils and sediments within the contaminated discharge pits would beexcavated and deposited directly without treatment. The discharge pitwould then be capped.

1 0 . 4 . 2 CRITERIA ASSESSMENT

Alternative 3 would be highly protective of human health and theenvironment, since the wastes would be treated to the extentpracticable. Additionally, this alternative would achieve compliancewith all ARARs. Long-term effectiveness and permanence would also beachieved. Durability tests are being conducted on the solidifiedmaterial as part of the bench scale treatability tests. Thisinformation will be helpful in further evaluating the long termeffectiveness of this option.

Alternative 3 would reduce the toxicity and mobility of the wastesthrough treatment; however, the volume of the wastes would not bereduced. Implementation of this alternative should provide a highdegree of short-term effectiveness, provided appropriate precautionsand control measures such as dust control are instituted during theremediation phase.

Implementation of this alternative is possible without undue technicalor administrative difficulty.

1 0 . 4 . 3 COST ESTIMATE

Capital expenditures under this alternative include costs for leasinga cement mixer, solidification materials costs, and remediation sitework. Additionally, as continued groundwater monitoring is acomponent of this alternative, the installation of two additional

10-17

monitoring wells is included. Indirect capital cost items includeengineering and design, contingencies, legal, regulatory, andmobilization/demobilization.

Annual costs associated with this remedial action are associated withannual groundwater sampling for the first five years after remedialsite work, then continued groundwater sampling once every five yearsfor twenty five years. This lesser amount of long-term groundwatermonitoring than assumed for Alternatives 1 and 2 is considered forAlternative 3 since the contaminated source material will beremediated under Alternative 3. Indirect annual costs includeadministration, contingency, and maintenance reserve.

The present worth cost estimate for Alternative 3 is $79,000 asdetailed in Table 10-4. The present worth cost is based on a life of30 years and an annual interest rate of 9 percent.

10 .5 ALTERNATIVE 4: CEMENT SOLIDIFICATION/OFF-SITE MUNICIPALLANDFILL DISPOSAL

10 .5 . 1 DESCRIPTION

Alternative 4 involves cement solidification fixation treatment of theleachable fraction of the Sierra Blanca waste material, followed bytransportation together with excavated non-leachable wastes to asuitable off-site RCRA Subtitle D-compliant landfill for finaldisposal. Alternative 4 is similar to Alternative 3, except thatfinal disposal of the wastes would be in an off-site landfill. Asdiscussed in Section 9, one qualified off-site landfill which appearswilling to accept the wastes is located 160 miles from the SierraBlanca site near Albuquerque, Transportation of the wastes would beaccomplished in standard public highway-approved bulk carrier trucks,of approximately 40 ,000 Ib. capacity, which would be covered toprevent generation of airborne contaminants. After disposal of thewastes in the landfill, management of the wastes would become the

10-18

TABLE 10-4ALTERNATIVE 3: CEMENT SOLIDIFICATION / ON-SITE DISPOSAL

PRELIMINARY COST ESTIMATE

Description: Excavate waste material, solidify teachable fraction with Portland cement, dispose on-siteInterest Rate: 9%Level of Accuracy: +50% to -30%DIRECT CAPITAL COSTS

COSTCOMPONENT

1 . Cement Mixer Lease2. Purchase Portland Cement3. Excavate LeachaWe Waste Material4. Solidify Leachabte Material with

Cement; Place in On-Site Landfill5. Excavate Non-Leachabte Material;Place Directly into On-Site Landfill

6, Earthwork/Grading7. Install Additional Monitoring Wells

TOTAL DIRECT CAPITAL COSTSINDIRECT CAPITAL COSTS1. Engineering & Design (20%)2. Contingency (15%)3. Other Indirect Costs

a. Legal (5%)b. Regulatory (5%)c. Mobilization/Demobilization (10%)TOTAL INDIRECT CAPITAL COSTSTOTAL CAPITAL COSTS (DIRECT +

UNIT QUANTITYMonth 1Bags 1 ,350C.Y. 225C.Y. 225C.Y. 178*L.S. 1Ea 2

INDIRECT)

UNITCOST

$5,0005

163020

5,0005,000

CAPITALCOST

$5,0006,8003.6006,8003,6005,000

10.000

$41 ,000

$ 8,2006,2002,1002,1004.100

£23000$64,000

* Material in discharge pit 1 will not be excavated since discharge pit 1 will be the on-site landfill location.

TABLE 10-4ALTERNATIVE 3: CEMENT SOLIDIFICATION / ON-SfTE DISPOSAL

PRELIMINARY COST ESTIMATE(Continued)

DIRECT ANNUAL/PERIODIC COSTS

1.

COSTCOMPONENT

Ground Water Sampling/AnalysisUNITEa

QUANTITYFREQUENCY (PER YR)Semi-annual*

UNITCOST

$1 ,000

DIRECTPERIODIC

COST$1,000

LIFE30

PRESENTWORTHCOSTS$5,000

TOTAL DIRECT PERIODIC COSTSTOTAL PRESENT WORTH OF DIRECT PERIODIC COSTSINDIRECT ANNUAL/PERIODIC COSTS1. Administration2. Maintenance Reserve &

ContingencyEaEa

AnnualAnnual

TOTAL PRESENT WORTH OF INDIRECT ANNUAL/PERIODIC COSTSTOTAL PRESENT WORTH (CAPITAL + ANNUAL/PERIODIC) COSTS

$1,000

$ 500500

3030

$5,000

$ 5,1005.100

$10,000

* Semi-Annual groundwater sampling for five years, then once every five years for 25 years.

responsibility of the landfill operator. For this reason, theoperator has stated that the landfill would accept the wastes only ifapproved by EPA and the state of New Mexico, and only if the wastesare certified as non-hazardous as per RCRA.

1 0 . 5 . 2 CRITERIA ASSESSMENT

As with Alternative 3, Alternative 4 would be highly protective ofhuman health and the environment since the wastes would be treated,and compliance with ARARs would be achieved. A high degree of long-term effectiveness and permanence would be provided since anappropriate municipal landfill is frequently monitored. Additionally,this alternative would achieve a high degree of permanence.

Alternative 4 would reduce the toxicity and mobility of the wastesthrough treatment. Implementation of this alternative should providea reasonable degree of short-term effectiveness, provided appropriateprecautions and control measures are instituted during the remediationphase. These measures would be those that minimize or preventexposure hazards to on-site workers and nearby residents duringremediation activities.

1 0 . 5 . 3 COST ESTIMATE

Capital costs for Alternative 4 include excavation of the contaminatedmaterial and associated site grading, on-site cement solidificationfixation treatment of the leachable fraction of the wastes, andtransportation of the material to a municipal landfill. Estimatedtipping fees required by the landfill are also included.Additionally, as continued groundwater monitoring is a component ofthis alternative, the installation of two additional monitoring wellsis included. Indirect capital cost items include engineering anddes ign , con t i ngenc i e s , legal , regu latory , andmobilization/demobilization.

10-21

Annual costs associated with this remedial action are associated withannual groundwater sampling for the first five years after remedialsite work, then continued groundwater sampling once every five yearsfor twenty five years. This lesser amount of long-term groundwatermonitoring than assumed for Alternatives 1 and 2 is considered forAlternative 4 since the contaminated source material will beremediated and removed from site under Alternative 4. Indirect annualcosts include administration, contingency, and maintenance reserve.

The present worth cost estimate for Alternative 4 is $235 ,000 asdetailed in Table 10-5. The present worth cost is based on a life of30 years and an annual interest rate of 9 percent.

10 ,6 ALTERNATIVE 5: OFF-SITE MUNICIPAL AND HAZARDOUS WASTELANDFILL DISPOSAL

10 ,6 . 1 DESCRIPTION

In lieu of treatment of the leachable fraction of the Sierra Blancawaste material, an alternate approach would be to dispose of it in ahazardous waste landfill. Alternative 5, therefore, consists ofexcavating the leachable wastes and transporting them withouttreatment to a suitable hazardous waste landfill. Because there isno requirement to dispose of the non-leachable wastes in a hazardouswaste landfill, these wastes would be excavated, kept segregated fromthe leachable wastes, and transported to a municipal landfill forfinal disposal.

Suitable hazardous waste landfills are available in Nevada, Utah, andColorado. A preliminary estimate of hazardous waste landfill disposalcosts was developed based on the Colorado facility, as it is theclosest to the Sierra Blanca site. When contacted, the hazardouswaste landfill in Colorado expressed an interest in accepting thewastes and provided a budget estimate for tipping fees.

10-22

TABLE 10-5ALTERNATIVE 4: CEMENT SOLIDIFICATION / OFF-SITE MUNICIPAL LANDFILL DISPOSAL

PRELIMINARY COST ESTIMATE

Description: Excavate waste material, solidify teachable fraction with Portland cement, transport to and dispose in municipal landfillInterest Rate: 9%Level of Accuracy: +50% to -30%DIRECT CAPITAL COSTS

COSTCOMPONENT UNIT QUANTITY

UNITCOST

1. Cement Mixer Lease Month 12. Purchase Portland Cement Bags 1,3503. Excavate Waste Material C.Y. 5704. Solidify Leachabte Material with C.Y. 225

Cement5. Transport to Landfill" $/ton-mite 1,882*(160 miles)6. Municipal Landfill Tipping Fee $/ton 1,8827. Earthwork/Grading L.S. 18. Lead & TCLP Analyses Ea 209. Install Additional Monitoring Wells Ea 2TOTAL DIRECT CAPITAL COSTSINDIRECT CAPITAL COSTS1. Engineering & Design (7%)2. Contingency (15%)3. Other Indirect Costsa. Legal (5%)b. Regulatory (5%)c. Mobilization/Demobilization (10%)TOTAL INDIRECT CAPITAL COSTSTOTAL CAPITAL COSTS (DIRECT + INDIRECT)

$5,0005

1630

0.2015

5,0001,2005,000

CAPITALCOST

$5,0006,8009,1006,800

60,20028,200

5.00024,00010.000

$155.000

$ 10,90023,300

7,8007,800

15.500£ 65.000$220,000

* Assumes landfill in AlbuquerqueNote: It is assumed that the

mass of the solidified wasteswould approximately doubleafter treatmentTotal mass = 41OT (leachablefraction) x 2 + 817T (non-teachabte fraction) = 1,637T

L -*

TABLE 10-5ALTERNATIVE 4: CEMENT SOLIDIFICATION / OFF-SITE MUNICIPAL LANDFILL DISPOSAL

PRELIMINARY COST ESTIMATE(Continued)

DIRECT ANNUAL/PERIODIC COSTS

1 .

COSTCOMPONENT

Ground Water Sampling/AnalysisUNITEa

QUANTITYFREQUENCY (PER YR)Semi-annual*

UNITCOST

$1 ,000

DIRECTPERIODIC

COST$1 ,000

LIFE30

PRESENTWORTHCOSTS$5.000

TOTAL DIRECT PERIODIC COSTSTOTAL PRESENT WORTH OF DIRECT PERIODIC COSTSINDIRECT ANNUAL/PERIODIC COSTS1. Administration2. Maintenance Reserve &

ContingencyEaEa Annual

Annual

TOTAL PRESENT WORTH OF INDIRECT ANNUAL/PERIODIC COSTSTOTAL PRESENT WORTH (CAPITAL + ANNUAL/PERIODIC) COSTS

$1,000

$ 500500

3030

$5,000

$ 5,1005.100

$10,000£235.000

* Semi-Annual groundwater sampling for five years, then once every five years for 25 years.

1 0 .6 . 2 CRITERIA ASSESSMENT

Alternative 5 would be protective of human health and the environmentsince the contaminated material would be removed from site and safelydisposed of. Compliance with ARARs would be achieved as disposal ofthe wastes would be permitted under current regulations. A similardegree of long-term effectiveness and permanence would be providedwith this alternative compared to on-site landfill disposal. Althoughtreatment would be provided prior to disposal in an on-site landfill,the continuous monitoring and active waste management present in apermitted hazardous waste landfill should provide a comparable levelof protectiveness. The long-term effectiveness and permanence of off-site hazardous waste landfill disposal would be less than treatmentand disposal in a municipal landfill, since treatment of the wasteswould be provided prior to disposal in the municipal landfill.Additionally, the level of waste management and waste monitoringprovided is comparable at both facilities. This alternative wouldachieve a high degree of permanence since the wastes are removed fromthe Sierra Blanca site.

Alternative 5 would reduce the mobility of the wastes as a result ofdisposal in a hazardous waste landfill. However, the toxicity andvolume of the wastes would not be affected. Implementation of thisalternative should provide a reasonable degree of short-termeffectiveness, provided the appropriate precautions and controlmeasures are instituted during the remediation phase involvingexcavation of the contaminated material.

10 .6 .3 COST ESTIMATE

Capital costs for Alternative 5 include excavation of the contaminatedmaterial and associated site work, transportation of the leachablefraction of the wastes to a hazardous waste landfill, andtransportation of the non-leachable fraction to a municipal landfill.Confirmation of total waste removal would be conducted by analyses of

10-25

lead in post-remediation surficial soils samples. Additionally, ascontinued groundwater monitoring is a component of this alternative,the installation of two additional monitoring wells is included.Indirect capital cost items include engineering and design,contingencies, legal, regulatory, and mobilization/demobilization.

Annual costs associated with this remedial action are associated withannual groundwater sampling for the first five years after remedialsite work, then continued groundwater sampling once every five yearsfor twenty five years. This lesser amount of long-term groundwatermonitoring than assumed for Alternatives 1 and 2 is considered forAlternative 5 since the contaminated source material will beremediated and removed from site under Alternative 5. Indirect annualcosts include administration, contingency, and maintenance reserve.

The present worth cost estimate for Alternative 5 is $344 ,000 asdetailed in Table 10-6. The present worth cost is based on a life of30 years and an annual interest rate of 9 percent.

Table 10-7 provides a cost summary of the five remediationalternatives for the Sierra Blanca Operable Unit (OU2) of the CimarronMining Corporation NPL site.

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TABLE 10-6ALTERNATIVE 5: OFF-SITE MUNICIPAL AND HAZARDOUS WASTE LANDFILL DISPOSAL

PRELIMINARY COST ESTIMATE

Description:Interest Rate:Level of Accuracy: +50% to -30%

Excavate waste material, dispose teachable fraction in hazardous waste landfill, dispose non-teachable fraction in municipal landfill9%

DIRECT CAPITAL COSTSCOST

COMPONENT1. Excavate Waste Material2. Transport Leachable Fraction

to Hazardous Waste Landfill*3. Hazardous Waste LandfillTipping Fee4. Transport Non-LeachabteFraction to Municipal Landfill"

5. Municipal Landfill Tipping Fee6. Earthwork/Gradity7. Lead & TCLP Analysis8. Install Additional Monitoring WellsTOTAL DIRECT CAPITAL COSTSINDIRECT CAPITAL COSTS1 . Engineering & Design (5%)2. Contingency (15%)3. Other indirect Costs

a. Legal (5%)b. Regulatory (5%)c. Mobilization/Demobilization (5%)TOTAL INDIRECT CAPITAL COSTSTOTAL CAPITAL COSTS (DIRECT

UNIT QUANTITYC,Y.

$/ton-miie(500 miles)$/ton$/ton-mite

$/tonL.S.EaEa

+ INDIRECT)

5705565567707701

202

UNITCOST

$160.202060.20

155,0001,2005,000

CAPITALCOST

$9,10055,600

114,50024,60011,5005,000

24,00010.000

$244,000

$ 12,20036,60012,20012,20012.200

£ 85.000

$329,000

* Assumes Facility in Colorado* Assumes Facility in Albuquerque

TABLE 10-6ALTERNATIVE 5: OFF-SITE MUNICIPAL AND HAZARDOUS WASTE LANDFILL DISPOSAL

PRELIMINARY COST ESTIMATE(Continued)

DIRECT ANNUAL/PERIODIC COSTS

COSTCOMPONENT

1 . Ground Water Sampling/AnalysisUNITEa

FREQUENCYSemi-annual*

QUANTITY(PER YR)

-•

UNITCOST$1 ,000

DIRECTPERIODIC

COST$1 .000

LFE30

PRESENTWORTHCOSTS$5,000

TOTAL DIRECT PERIODIC COSTSTOTAL PRESENT WORTH OF DIRECT PERIODIC COSTSINDIRECT ANNUAL/PERIODIC COSTS1. Administration2. Maintenance Reserve &Contingency

EaEaAnnualAnnual

TOTAL PRESENT WORTH OF INDIRECT ANNUAL/PERIODIC COSTSTOTAL PRESENT WORTH (CAPITAL + ANNUAL/PERIODIC) COSTS

$1,000

$ 500500

3030

$5,000

$ 5,1005.1 QQ

$10,000

* Semi-Annual groundwater sampling for five years, then once every five years for 25 years.

TABLE 10-7COST SUMMARY OF REMEDIATION ALTERNATIVES

PresentAlternative_____ Worth Cost

1. No Action $ 48,0002. Institutional Controls 93,0003. Cement Solidification / On-Site 79,000

Disposal4. Cement Solidification / Off-Site 235,000

Municipal Landfill Disposal5. Off-Site Municipal and 344,000

Hazardous Waste LandfillDisposal