Focused Feasibility Study for Operable Unit 1 Colorado ...Colorado Smelter OU1 Focused Feasibility Study Report, Revision 3 Page 5 June 30, 2017 1.0 Introduction and Purpose This Focused

FOCUSED FEASIBILITY

COLORADO SMELTER SUP

PUEBLO, PUEBLO COUNT

FOCUSED FEASIBILITY STUDY FOR OPERABLE UNIT 1

COLORADO SMELTER SUPERFUND SITE

PUEBLO, PUEBLO COUNTY, COLORADO

June 30, 2017Revision 3

Prepared for:

U.S. EPA Region 8Denver, Colorado

Prepared by:

3000 Youngfield Street, Ste. 300Wheat Ridge, Colorado 80215

303-274-5400

FOR OPERABLE UNIT 1

Colorado Smelter OU1 Focused Feasibility Study Report, Revision 3 Page 2

June 30, 2017

TABLE OF CONTENTS

1.0 Introduction and Purpose .................................................................................................................. 5

2.0 Background Information.................................................................................................................... 6

2.1. Site Description and History ...................................................................................................... 6

2.2. Nature and Extent of Contamination........................................................................................ 7

2.3. Conceptual Site Model and Exposure Scenarios...................................................................... 8

2.4. Development of Preliminary Remediation Goals..................................................................... 9

3.0 Remedial Action Objectives and Applicable or Relevant and Appropriate Requirements .......10

3.1. Remedial Action Objectives for OU1 ......................................................................................10

3.2. Summary of ARARs .................................................................................................................11

4.0 Development of General Response Actions and Identification and Screening of Technologies 13

4.1. General Response Actions ........................................................................................................13

4.2. Identification and Screening of Technology Types and Process Options ............................13

4.2.1. Soil ......................................................................................................................................13

4.2.2. Dust.....................................................................................................................................16

5.0 Description of Alternatives...............................................................................................................17

5.1. Alternative 1: No Action...........................................................................................................17

5.2. Alternative 2: Soil Removal and Replacement to 12 Inches Below Ground Surface and Notto Exceed Area Remediation with Indoor Cleanups as Needed .......................................................18

5.3. Alternative 3: Soil Removal and Replacement to 18 Inches Below Ground Surface withIndoor Cleanups as Needed..................................................................................................................19

6.0 Individual and Comparative Analysis of Alternatives ..................................................................20

6.1. Alternative 1: No Action...........................................................................................................20

6.2. Alternative 2: Soil Removal and Replacement to 12 Inches Below Ground Surface and Notto Exceed Area Remediation with Indoor Cleanups as Needed .......................................................20

6.3. Alternative 3: Soil Removal and Replacement to 18 Inches Below Ground Surface withIndoor Cleanups as Needed..................................................................................................................21

6.4. Comparative Analysis...............................................................................................................22

7.0 References ..........................................................................................................................................22


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Figures

Figure 1-1 Colorado Smelter OU1 Site Location

Figure 1-2 Sampled Properties, Colorado Smelter Superfund Site OU1

Figure 1-3 2016 - 2017 Early Action Indoor Dust Emergency Removal Response

Figure 2-1 Conceptual Site Model

Figure 5-1 Alternative 2 Soil Cleanup Flowchart


Tables

Table 2.1 Preliminary PRGs for Colorado Smelter OU1

Table 3.1 State and Federal Applicable or Relevant and Appropriate Requirements

Table 4.1 Evaluation of General Response Actions and Process Options for Residential Soil

Table 4.2 Evaluation of General Response Actions and Process Options for Indoor Dust

Table 6.1 Comparison of Total Costs of Remedial Alternatives

Table 6.2 Summary of Remedial Alternative Evaluation Criteria

Appendices

Appendix A - Preliminary Identification of Chemicals of Potential Concern

Appendix B - Preliminary Remediation Goals

Appendix C - Action Memorandum – Approval and Funding for an Emergency Removal ActionInvolving the Cleanup of Lead-Contaminated Indoor Dust in Residential Areas of Pueblo, CO, as a resultof Smelting Activities at the Colorado Smelter Site

Appendix D - Bioavailability Technical Memorandum – Colorado Smelter Superfund Site, Pueblo,Pueblo County, Colorado

Appendix E – Evaluation of the Contribution of Outdoor Lead in Soil to Indoor Lead in Dust at ColoradoSmelter Superfund Site

Appendix F – Agency for Toxic Substances and Disease Registry Technical Assistance for Lead andArsenic in Indoor Dust Related to Colorado Smelter NPL Site, Pueblo, Colorado

Appendix G - American Academy of Pediatrics Recommendations on Medical Management of ChildhoodLead Exposure and Poisoning

Appendix H – Comparison of Total Cost of Remedial Alternatives


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Acronyms

ARARs Applicable or Relevant and Appropriate RequirementsATSDR Agency for Toxic Substances and Disease RegistryBTV background threshold valuesCERCLA Comprehensive Environmental Response, Compensation, and Liability ActCF&I Colorado Fuel & IronCDPHE Colorado Department of Public Health and the EnvironmentCSM conceptual site modelCOPCs contaminants of potential concernCLP contract laboratory programDMA Demonstration of Methods ApplicabilityDU Decision UnitEPA United States Environmental Protection AgencyFFS Focused Feasibility StudyGRAs General Response ActionsHHRA human health risk assessmentICs Institutional ControlsICP-MS inductively-coupled plasma mass spectrometryIEUBK Integrated Exposure Uptake Biokinetic ModelMSD Soil-to-Dust mass transfer ratioMRL Minimum Risk LevelNTE Not to ExceedOU Operable UnitPCCHD Pueblo City-County Health DepartmentPRG Preliminary Remediation GoalPWT Pacific Western Technologies, Ltd.QAPP Uniform Federal Policy Quality Assurance Project PlanRAC2 Remedial Action ContractRAOs remedial action objectivesRBA relative oral bioavailabilityRBC risk-based concentrationRBSLs Risk Based Screening LevelsRCRA Resource Conservation and Recovery ActRI Remedial InvestigationROD Record of DecisionSARA Superfund Amendments and Reauthorization Act of 1986Site Colorado Smelter Superfund site, Pueblo, Pueblo County, ColoradoXRF X-Ray Fluorescence spectrophotometry


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1.0 Introduction and Purpose

This Focused Feasibility Study for Operable Unit 1 (OU1) (FFS) is being prepared by Pacific WesternTechnologies, Ltd. (PWT) under Remedial Action Contract (RAC2) Work Assignment No. 136-RICO-08UA, U.S. EPA Contract No. EP-W-06-006 for the United States Environmental Protection Agency(EPA) Region 8. This report summarizes the Remedial Investigation (RI) data collected betweenDecember 2015 and June 2016 and documents the screening, development, and comparative analysis(nine criteria) of remedial alternatives for the Colorado Smelter Superfund site (Site) located in Pueblo,Colorado. This report also presents preliminary remedial action objectives (RAOs) and Applicable orRelevant and Appropriate Requirements (ARARs) in support of an early interim action record of decision(i-ROD) for OU1, Community Properties, of the Site. This data set and related analyses will supportremedial decision making for residential properties within the OU1.

The Demonstration of Methods Applicability (DMA) conducted in 2015 assessed soils at 12 residentialproperties and 6 select locations of the former smelter/slag area. Sampling was conducted in accordancewith the EPA-approved Uniform Federal Policy Quality Assurance Project Plan for Demonstration ofMethods Applicability at Colorado Smelter, Revision 2 (DMA QAPP) (PWT 2015a), dated May 8, 2015.Data from the DMA was used to optimize sampling strategies, sample preparation, and analyticalmethods for the larger Remedial Investigation (RI) sampling effort for residential properties at the Site.RI sampling was initiated in December 2015, in accordance with the EPA-approved Uniform FederalPolicy Quality Assurance Project Plan for OU1 Remedial Investigation at Colorado Smelter, Revision 0(RI QAPP), dated November 11, 2015 (PWT 2015b). Results from the 12 DMA properties and the first290 properties sampled as part of the RI are included in this report. Ongoing RI sampling is conducted inaccordance with Revision 3 of the RI QAPP (PWT 2016a).

Figure 1-1 shows the general location of the Site/Preliminary Study Area, and Figure 1-2 identifies thefirst 302 yards sampled during the DMA/RI. Soils and indoor dust were assessed for the potentialpresence of arsenic, lead, and other heavy metals related to the historical Colorado Smelter. Data fromthe 302 properties and 6 smelter/slag areas evaluated during the DMA and subsequent RI sampling effortwill help the EPA to determine the nature and extent of smelter related contamination at the Site and willsupport the EPA in conducting a baseline human health risk assessment (HHRA). These data havealready supported the preliminary determination of the contaminants of potential concern (COPCs)presented in the April 2017 Technical Memorandum Preliminary Identification of Chemicals of PotentialConcern (PWT 2017c), and calculation of preliminary remediation goals for the site in the May 2017Technical Memorandum Preliminary Remediation Goals for Soil (PWT 2017d). These memoranda havebeen included as appendices A and B, respectively.

The purpose of this Report is to present a focused analysis of the remedial alternatives considered, thoserejected, and the basis for the evaluation. The reason this report is being prepared in advance of thecompletion of RI sampling is that review and analysis of data to date indicate that early interim actionmay be necessary to achieve significant risk reduction quickly and to prevent further environmentaldegradation, while a final remedial solution is being developed. Specifically, indoor dust cleanups werecompleted during 2016 and 2017 at 27 homes (located on 26 separate parcels) within the OU1preliminary study area as part of an emergency removal action. This early interim action indoor dustremoval response effort was deemed necessary due to the high levels of lead in interior dust and soil andthe risk to human health predicted by the IEUBK model. Additional information on the emergencyremoval action can be found in Appendix C, Action Memorandum – Approval and Funding for anEmergency Removal Action Involving the Cleanup of Lead-Contaminated Indoor Dust in ResidentialAreas of Pueblo, CO, as a result of Smelting Activities at the Colorado Smelter Site (EPA 2016b).Residential yard soil cleanups at these locations should occur as soon as possible to prevent


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recontamination. Figure 1-3 identifies the locations of homes where indoor dust has already beenremediated. It is also critical that additional dust and soil cleanups begin as soon as possible at additionalproperties in the study area, based on RI data, the identification of elevated blood lead levels in someresidents, and community interest.

2.0 Background Information

2.1. Site Description and History

The Colorado Smelter (also known as the Colorado Smelting Company and the Eiler's Smelter) was oneof five smelters in Pueblo at the turn of the 20th century. This smelter processed silver-lead ore from theMonarch Pass area and operated from 1883 to 1908. There is a steel mill (Evraz/Rocky MountainSteel/Colorado Fuel & Iron (CF&I)) located to the south of the Site that is still operating. The ColoradoDepartment of Public Health and the Environment (CDPHE) Resource Conservation and Recovery Act(RCRA) program is the lead agency for that operating facility.

In 2006, a Colorado State University-Pueblo professor and co-authors published a paper that describedheavy metals in Pueblo surface soils. The authors found that in some areas, the topsoil in Pueblo has morearsenic, cadmium, mercury and lead than the average levels found nationally in soils. The authors of the2006 report recommended more soil sampling to identify hotspots within the city.

The CDPHE, under a cooperative agreement with the EPA, investigated the Blende Smelter, FountainFoundry, and Colorado Smelter sites in Pueblo because they were in, or close to, residentialneighborhoods, and previous soil sampling data indicated the need for more detailed sampling of theseresidential areas. The Blende Smelter was remediated using an EPA-lead removal action. One of the threeremaining smelters, Pueblo Smelter/Rockwool facility, is bordered by commercial/industrial propertiesand was addressed via a removal action in which source material was capped in place. The former NewEngland/Massachusetts Smelter and the Philadelphia Smelters were located on the eastern edge of thesteel mill facility. It is unknown if these smelters have impacted any nearby communities (CDPHE 2011).

Historical data that were collected by the CDPHE in 1994 and EPA contractors in 1995 indicated thepresence of elevated levels of lead and arsenic in soils; however, the studies were not systematic andlacked sufficient data density to clearly determine if metals posed a significant threat to residents livingnear the former smelter. In 2010, CDPHE collected 434 surface soil samples from 47 yards in the Eilers andBessemer residential neighborhoods surrounding the Colorado Smelter, including the old slag pile area andtwo background locations. The former smelter site consists of an approximate 700,000 square foot slag pilethat is 28 feet high in places. Lead levels in the slag pile ranged from 478 to 26,500 mg/kg and arsenicranged from 30 to 1,740 mg/kg as determined by inductively-coupled plasma mass spectrometry (ICP-MS).

The lead levels measured using X-Ray Fluorescence spectrophotometry (XRF) on composite samples ofresidential soils collected from the area south and east of the former smelter ranged from 300 to 785 mg/kg.The screening level benchmark that the EPA and CDPHE have typically used for lead is 400 mg/kg.Arsenic concentrations varied from 100 to 340 mg/kg range in an area immediately south of the formersmelter site. The screening level benchmark that the EPA and CDPHE have typically used for arsenic hasranged from 40 to 70 mg/kg at similar sites in Region 8. In addition, these concentrations are well abovepreliminary background levels designated for that field effort (47 mg/kg for lead and 16 mg/kg for arsenic).

In May and June of 2015, the EPA conducted a Demonstration of Methods Applicability Study (DMA),optimizing the sampling and analytical approaches to be used in the larger RI sampling effort, whichbegan in December 2015. Together, the DMA and the RI sampling efforts have characterized the


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concentrations of arsenic, lead and other metals in soil in over 300 residential yards and in indoor dust inover 100 homes. Data from this systematic sampling effort is beginning to provide a picture of the natureand extent of contamination at the Site.

2.2. Nature and Extent of Contamination

The OU1 RI sampling effort has included collection of residential soil and indoor dust samples in thepreliminary study area, which consists of a ½-mile radius area centered on the former smelter stack. Thereare approximately 1,900 parcels within the study area, approximately 1,500 of which are residentialparcels. RI soil samples were collected from four distinct depth intervals, typically 0-1, 1-6, 6-12 and 12-18 inches below ground surface, but DMA sampling did not include indoor dust sampling and someDMA soil samples were collected from 0-2 and 2-6 inches below ground surface, due to differences inyards with bare soils versus yards with grass or other cover. Soil samples were dried, disaggregated andsieved to provide reproducible results, and then analyzed by XRF for metals. XRF results for 5,828samples from 290 RI properties are presented in the Technical Memorandum titled PreliminaryIdentification of Contaminants of Potential Concern (COPCs) (PWT 2017c). As explained in the RIQAPP, Revision 1 (PWT 2016a), a subset of the RI soil samples collected from residential properties wasselected for ICP-MS confirmation analysis through the EPA contract laboratory program (CLP), and theresults compared to XRF results from the same samples. The results of this correlation, as well as theresults of the CLP analyses are discussed in more detail in the COPC technical memorandum, which isincluded as Appendix A (PWT 2017c).

The RI QAPP documents the following 17 metals that were considered COPCs: antimony, arsenic,barium, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, selenium,silver, thallium, vanadium, and zinc (PWT 2015b). Based on the analyses described and presented in theCOPC technical memorandum, 12 of the 17 metals antimony, arsenic, cadmium, cobalt, copper, lead,manganese, mercury, nickel, thallium, vanadium, and zinc were considered COPCs for OU1, because themaximum concentrations for soil samples exceeded the risk-based concentrations (RBCs) andbackground for one or more depth ranges. However, only four out of 224 samples (less than 2% of thedata set) exceeded the RBSL and all 224 samples were less than 20% of the noncancer RSL for mercury.In addition, mercury is not a known contaminant associated with the lead/silver ore smelting historicallyknown to have occurred at the Site (PWT 2017c).

At this time, arsenic and lead appear to be the main risk drivers for the Site. Indoor dust samples werecollected from homes in OU1 where the resident and the property owner granted consent for indoor dustsampling. Samples were collected using a specialized high-volume, small surface area vacuum sampler,which was designed specifically to collect indoor dust for chemical analysis. The standard operatingprocedure PWT-ENST-430 for dust sampling was developed using the American Society for Testing andMaterials protocol D5438-11, Standard Practice for Collection of Floor Dust for Chemical Analysis.Samples were collected from individual rooms, when possible, or composited over multiple rooms in theliving area, if necessary to obtain enough volume for analysis. When accessible, attics were also sampled.These dust samples were analyzed for metals with ICP-MS by EPA-assigned CLP laboratories.

Elevated concentrations of arsenic and lead were identified in residential soils and indoor dust, and asstated above, appear to be the main risk drivers for the Site. The average concentrations of lead in alldepths of soils collected from the first 302 homes sampled ranged from 7.27 to 3,910 mg/kg. Dustsamples from 102 homes were sent to an offsite laboratory and the lead concentrations in indoor dustfrom living areas have ranged from 8.2 to 2,060 mg/kg. Arsenic concentrations ranged from very lowlevels (4.3 mg/kg) to over 200 mg/kg in residential soil samples and from 1 to 47 mg/kg in indoor dustsamples (EPA 2017). Based on the results of the residential soil and indoor dust sampling, it appears that


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elevated concentrations of arsenic and lead in exterior soil are related to the elevated concentrations ofarsenic and lead measured in indoor dust. The EPA has determined that early action is needed to addressunacceptable risks from arsenic and lead in these two media.

2.3. Conceptual Site Model and Exposure Scenarios

The initial conceptual site model (CSM) developed at the beginning of the RI is periodically updated toincorporate new data about the Site. Primary sources of contamination that are considered for the Siteinclude fugitive dust and particulate air emissions from the historic main smelter stack, solid wastes suchas slag and slag-impacted soils, and liquid wastes, such as process solutions, acids, and rinsates fromhistoric facility operations. Secondary sources of non-smelter related contamination from the historic useof leaded gasoline and potential historic use of arsenical pesticides were also considered. Figure 2-1presents a graphical depiction of the conceptual site model.

Findings from previous screening investigations and early RI sampling indicate elevated concentrations ofarsenic and lead in multiple residential soil and indoor dust samples. A baseline human health riskassessment (HHRA) will be performed at a later date and will include all available sampling results,exposure assessment, toxicity assessment, risk characterization, and uncertainty analysis. The HHRA willalso quantify the risks for each complete source-pathway-receptor as appropriate.

A site-specific background study will be conducted, because multiple other sources of metals are presentin the environment both naturally and as a result of human activities. The background study results willbe used to support the HHRA for the OU1 RI and for the Site at large. The background study results alsowill be used as part of the final COPC determination.

Release mechanisms:

Through the mechanisms of air dispersion and deposition, air emissions from the former main smokestack and fugitive emissions from the slag piles had the potential to impact surface soils and surfacewater, potentially contaminating these media. Fugitive dust emissions from the former smelter sitecaused by wind or human activity may still occur. The 0.5-mile radius of the preliminary study areasurrounding the former main stack of the Colorado Smelter was based on the observation that, for mostsmelters with similar stack height, greater than 90% of particulates drop out with in 0.5 mile. It has alsobeen noted that “soil lead concentrations decrease with distance from the source and depend greatly onwind speed and wind direction (EPA, 2006b).

Site-related contaminants had (and still have) the potential to impact surface water of the Arkansas Riverthrough the mechanisms of surface runoff and erosion. Waste piles of slag have the potential to impactsurface soils through direct contact, and the potential to impact subsurface soils and groundwater underthe Site by infiltration of rain or snowmelt that leaches metals contamination out of the slag, transportingthis contamination down the soil column. Surface water and groundwater will be addressed by the OU2CSM and OU2 RI. Particulates containing site-related contaminants can also become entrained in the airas a result of wind or human activities.

Potential receptors and exposure pathways:

After site-related contamination migrated from its original sources to the outdoor exposure media beingevaluated for this RI (surface soil and subsurface soil), interactions between these media provide ongoingpathways for contaminant transport, including transport into homes, contributing to elevatedconcentrations of arsenic or lead in indoor dust.


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The exposure routes by which human receptors may come in contact with the contaminants includeinhalation of the air-entrained particles/dust; ingestion (eating or drinking); and dermal contact (directphysical contact).

Potential exposure routes and receptors will be described in more detail in the HHRA. Ecological riskassessment will be performed within the RI for OU2.

Land Use Considerations:

The preliminary study area consists of approximately 1,900 owned parcels, 1,500 residential parcels, and400 other properties (five parks, one school, alleys, and commercial properties) located within a 0.5-mileradius of the former smelter, primarily in the Eilers, Bessemer, and Grove neighborhoods. Definition ofthe preliminary study area also considered the distance between the former Colorado Smelter main stackand the edges of the neighborhoods to the north, west, south, and east. The preliminary study areaboundary and number of residences investigated may be increased or decreased as data provide moreinformation about the area affected by the Colorado Smelter.

In addition to residential properties, five parks, one school and numerous vacant lots, commercialproperties and alleys will be sampled as part of the RI. If sampling results for these properties indicatehigh levels of arsenic and lead, early interim action may be needed at these locations as well. A moredetailed CSM is presented in the revised RI QAPP (PWT 2016a).

2.4. Development of Preliminary Remediation GoalsIn order to calculate PRGs, the following general process was followed, although the method variedslightly depending on the COPC (specifically between lead and other COPCs):

• First, a risk-based concentration (RBC) was calculated using COPC-specific toxicity values andexposure parameters for a residential receptor.

• Second, the RBC was compared to background threshold values (BTV) identified for the Site(PWT, 2017c). The USGS background study, Geochemical and Mineral Data for Soils of theConterminous United States (Smith et al. 2013) was used and is representative of geogenic(naturally occurring) background, and does not include urban background, which will beevaluated in a site-specific background study to be conducted as part of the RI effort.

• Finally, the higher of the RBC and the BTV was selected as the PRG.

Site-specific values were developed for two exposure parameters used in the calculation of PRGs. Theseare the relative oral bioavailability (RBA) values for metals (lead and arsenic), as reported in theBioavailability Technical Memorandum (PWT, 2017a), and the mass fraction of soil in dust, as reportedin the technical memorandum, Site-Specific Soil-to-Dust Mass Transfer Ratio (MSD) CalculationColorado Smelter Superfund Site, Pueblo, Pueblo County, Colorado (PWT, 2017b), included asappendices C and D, respectively. The site-specific RBA for arsenic (0.48) is lower than the default RBA(0.60), while the site-specific RBA for lead (0.63) is slightly higher than the default RBA for lead (0.60).

A site-specific mass fraction of soil in dust (MSD) value was developed for lead from a subset of data for102 homes from OU1 with dust samples collected and analyzed for metals (PWT, 2017b). The MSD

value represents an estimate of the fraction of lead in dust that is attributable to lead in soil at a residencewithin OU1. This site-specific MSD value, which was 0.36, was used for all COPCs. In addition,modifications to the RBC calculations were made to allow for both dust and soil ingestion to be


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considered. The site-specific MSD value was used in those calculations to estimate the dust concentrationrelative to the soil concentration.

Because all the chronic RBCs calculated for lead exceed the background threshold value (BTV) of 49.8mg/kg (PWT, 2016c), the potential PRGs for chronic exposure at the Colorado Smelter site are the sameas the RBCs. Based on current defaults used in the Integrated Exposure Uptake Biokinetic (IEUBK)model, with an updated ingestion rate and site-specific values for MSD and RBA, the potential PRG forchronic exposure to lead is 740 mg/kg. Although EPA’s current policy for target blood lead is 10 µg/dL,the December 2016 Office of Land and Emergency Management (OLEM) Directive (#9200.2-167)suggests that a target blood lead level of 2-8 µg/dL may be more appropriate and considered in somecases. For example, the 2013 Integrated Science Assessment for Lead found that several studies haveobserved “clear evidence of cognitive function decrements in young children with blood lead levelsbetween 2-8 µg/dL” (EPA 2013). For this reason and to provide Colorado Smelter Superfund Site withthe most thorough and health protective lead cleanup as possible, a PRG of 350 mg/kg has been selectedfor lead. Using the IEUBK model and site-specific exposure parameters, the blood lead level predicted tobe associated with 350 mg/kg is 6.24 µg/dL. The risk management process did not make any change tothe arsenic PRG of 61. These PRGs are intended for comparison to area-weighted averaged results foreach property.

Because all the acute RBCs calculated for lead exceed the background threshold value (BTV) of 49.8mg/kg (PWT, 2017c), the potential PRGs for acute exposure at the Colorado Smelter site are the same asthe RBCs. Based on current defaults used in the IEUBK model, with an updated ingestion rate and site-specific values for MSD and RBA, the PRG for acute exposure to lead in residential yard soil is 1,918mg/kg. This PRG is intended for comparison to specific Decision Unit (DU) and depth results and wouldbe applied as a not-to-exceed value to protect against acute exposure effects.

The risk management soil PRGs of 61 mg/kg for arsenic and 350 mg/kg lead have been used for this FFS.Preliminary indoor dust PRGs were recommended in the Technical Assistance for Lead and Arsenic inIndoor Dust Related to Colorado Smelter NPL Site, Pueblo, Colorado letter report provided by theAgency for Toxic Substances and Disease Registry (ATSDR) as 275 mg/kg lead and 160 mg/kg arsenic(minimum risk level [MRL]) (ATSDR 2016). This letter report is included as Appendix F to this report.However, the noncarcinogenic RBC of 61 mg/kg was selected as the indoor dust PRG for arsenic. Thislevel of 61 mg/kg was selected because the cancer risk (RBC) of 12 mg/kg is lower than the naturalbackground (BTV) (12.7 mg/kg). It is also expected to be below the site-specific urban background. Thislevel, 61 mg/kg is protective and conservative when compared to 120 mg/kg, which is the cancer risk ofapproximately 1 additional instance of cancer in 10,000 people (10-4), or when compared to the ATSDRvalue (See Appendix A for more information). PRGs for all COPCs are presented in Table 2.1 of thisFFS. Final residential soil and indoor dust cleanup numbers will be established in the proposed plan andearly interim action ROD.

3.0 Remedial Action Objectives and Applicable or Relevant and Appropriate Requirements

3.1. Remedial Action Objectives for OU1Remedial Action Objectives (RAOs) are developed by the EPA to protect human health and theenvironment at the Site. The overall OU1 RAO is to protect human health from Site-relatedcontaminants.

EPA considers current and future use of the site when determining RAOs. Based on current zoning of thesite, plausible future uses at most properties include residential use. Thus, the EPA has determined thatresidentially zoned property within OU1 should be remediated to meet residential land use criteria. Non-


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residential properties within OU1, (i.e., parks, a school, unpaved streets/alleys, and commercialproperties) will be evaluated as part of future response actions. Institutional controls (ICs) will be neededfor properties where waste is left in place above levels safe for unlimited use and unrestricted exposure.The need for ICs at specific properties and what kind of ICs may be needed will be developed duringimplementation of the early interim action residential property cleanups, and the public will have anopportunity to review and comment on that portion of the remedy as part of the final ROD for OU1.Institutional controls developed for OU1 will comply with the Colorado Environmental Covenant Statute,C.R.S. §§ 25-15-317 et seq.”

The following OU1-specific (Community Properties) RAOs were developed for arsenic and lead inresidential soil and indoor dust.

RAOs for Arsenic and Lead in Soil• Reduce exposure to soils exceeding health based PRGs for arsenic and lead. The arsenic PRG is

61 milligrams per kilogram (mg/kg) and the lead PRG is 350 mg/kg.

RAOs for Arsenic and Lead in Indoor Dust• Reduce exposure to indoor dust exceeding the health based PRGs for arsenic and lead in indoor

dust. The indoor dust arsenic PRG is 61 mg/kg and the indoor dust lead PRG is 275 mg/kg.

A critical and ongoing component of the OU1 RI includes EPA providing funding for the Pueblo City-County Health Department (PCCHD) to establish and carry out a lead screening, health education andoutreach program. Their program will receive ongoing annual support throughout the RI to screenresidents for elevated blood lead, conduct healthy home risk assessments and reports, provide healtheducation and outreach materials to homeowners, residents, and physicians, and respond to priorityproperties identified by the EPA through the property-specific evaluation of indoor dust and outdoor soillevels.

RAOs have not been developed for animals, plants and other such ecological receptors at the Site at thistime. They will be developed as part of the Operable Unit 2 (OU2 – Former Smelter Area) RI anddocumented in a future OU-specific ROD.

Media of Concern:

At this time, both residential soil and indoor dust are media of concern at some properties within OU1.

Areas of Concern:

The areas of concern covered by these alternatives are residential properties in OU1 where concentrationsof arsenic and/or lead in soil and/or indoor dust exceed the Site PRGs.

3.2. Summary of ARARsThe Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) as amendedby the Superfund Amendments and Reauthorization Act of 1986 (SARA), requires that all remedialactions comply with, or justify the waiver of, the applicable or relevant and appropriate requirements(ARARs) of other federal and state environmental and public health statutes. Applicable or relevant andappropriate requirements (ARARs) necessitate a two-part analysis: first, a determination is made whethera given requirement is applicable; then, if not applicable, a determination must be made whether it is bothrelevant and appropriate.


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Identification of ARARs is done on a site-specific basis and they are categorized as being chemical-,action, or location-specific requirements.

Chemical-specific requirements are usually health- or risk-based numerical values that maydefine acceptable exposure levels. These values establish the acceptable amount/concentration ofa chemical that can be discharged or left in the environment.

Action-specific requirements are usually technology- or activity-based requirements pertaining toa particular treatment or disposal method.

Location-specific requirements are restrictions placed on the concentration of hazardoussubstances or the conduct of activities solely because they occur in special locations, such aswetlands or floodplains.

A requirement under other laws may be either “applicable” or “relevant and appropriate”, but it cannot beboth.

As stated in EPA guidance, “Applicable” requirements are those which specifically address hazardoussubstances, pollutants, contaminants, remedial action, or other circumstances or situations found atComprehensive Environmental Response, Compensation, and Liability Act (CERCLA) sites. “Relevantand appropriate” requirements are not “applicable”, but address situations similar enough to thoseencountered at CERCLA sites that their use is well suited to the Site. This similarity is determined usingbest professional judgment, taking into account the:

1. purpose of the requirement;

2. medium, substance and action regulated; and

3. use or potential use of affected resources, relative to the nature of these factors at the Site.

Only applicable requirements are evaluated for off-site actions, whereas both applicable and relevant andappropriate requirements are evaluated for on-site actions. In addition, on-site actions must comply withsubstantive requirements of ARARs but not the related administrative and procedural requirements. Forexample, remedial actions conducted on-site would not require a permit but would be conducted in amanner consistent with the permitted conditions. In some cases, a requirement may be relevant but notappropriate, given a site-specific circumstance; such a requirement is therefore not an ARAR for the Site.Both “applicable” and “relevant and appropriate” requirements were considered in screening anddeveloping the range of remedial alternatives for the Site.

In addition to ARARs, to-be-considered (TBC) materials are evaluated and used to determine thenecessary level of cleanup for protection of health or the environment. TBCs are non-promulgatedadvisories, guidance, criteria, and proposed standards issued by Federal, State, and public health agenciesthat are not legally binding and do not have the status of potential ARARs. However, they may beconsidered along with ARARs as part of the site risk assessment and may be used in determining thenecessary level of cleanup for protection of health or the environment.

Table 3.1 presents ARARs for the OU1 proposed remedial alternatives at the Site. The ARARs arepresented by media of concern and by Federal or State requirements that may apply at the Site. As workprogresses and more information is gathered, the list of ARARs may be modified. In addition to ARARs,TBCs are included where the source of information was deemed useful.


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4.0 Development of General Response Actions and Identification and Screening of Technologies

The purpose of this section is to present General Response Actions (GRAs) which may be implementableat OU1 and to identify and screen technology types and process options for inclusion in remedialalternatives for the Site.

4.1. General Response ActionsA variety of engineering controls were considered as GRAs for the Site, including containment controls,migration controls, removal, and chemical and physical treatment.

4.2. Identification and Screening of Technology Types and Process OptionsProcess options for implementing the engineering controls and technology types associated with theGRAs identified in the previous section were screened for effectiveness, implementability, and cost inaccordance with EPA guidance (EPA 1988). The screening of technology types and process options isdetailed in the following narrative and summarized for soil in Table 4.1 and for indoor dust in Table 4.2.

• Effectiveness – The effectiveness evaluation focuses on the potential effectiveness of the processoptions in handling the estimated volume of soils or areas of concern and meeting the RAOs, thepotential risk to human health and the environment during implementation, and how proven orreliable the technology and process is for handling the contaminants and conditions at the Site.

• Implementability – The implementability evaluation examines the technical and administrativefeasibility of implementing a technology and process option.

• Cost – The cost evaluation looks at relative capital costs rather than detailed estimates.Engineering judgment is used to determine whether the costs associated with each process optionare high, medium, or low relative to other process options under that technology type.

4.2.1. Soil

Containment controls are engineered barriers which limit exposure to and the potential mobility of soil orwaste. Typical process options for containment include engineered soil cover, soil-clay cover, asphaltcover, concrete cover, and synthetic membrane cover. Soil and soil-clay covers are somewhat effectiveprovided they are appropriately maintained. Asphalt, concrete and synthetic membrane covers may behighly effective when long term maintenance is applied. Covers are difficult to install and maintain oversmall, non-contiguous areas such as residential yards or portions of yards, making the implementability ofthese options low for this Site. Cost to construct and maintain soil covers is relatively low, costs for soil-clay covers are medium, and costs to install and maintain asphalt, concrete or synthetic covers arerelatively high. Although there are advantages and disadvantages to each of these containment processoptions, all require significant long term maintenance to be effective. Because of this, covers are notretained for further consideration.

Migration controls reduce the movement of contamination from source areas into the surrounding soils.Surface controls are the only migration control technology considered. Process options for surfacecontrols include grading, revegetation, and erosion protection. These options are generally employed inconcert at larger sites, to reduce the amount of precipitation coming in contact with contaminated soils orwastes. Grading, erosion control and revegetation can be effective in reducing the migration ofcontaminants away from source areas, however, the soil disturbance associated with grading and


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establishing new vegetation could expose workers or neighbors to airborne dust containing unacceptablelevels of arsenic and/or lead. Storm water flow must be considered when grading is employed both toprotect the replaced soil from erosion and to ensure there are not negative impacts to neighboringproperties. Storm water drainage controls may be required as part of this response action. Surfacecontrols require ongoing maintenance in order to remain effective in the long term. These considerationsmake the effectiveness of surface controls low when considered as a stand-alone option. Grading,revegetation and erosion control are retained to be used in conjunction with soil removal and replacementoptions for residential areas.

Soil removal and replacement is a three stage process involving excavation of contaminated soils,disposal of excavated materials, and replacement with clean soils. In some cases, where contamination isleft in place below the depth of the excavation, a visible barrier material will be placed, such as snowfence or geotextile. Conventional earth moving refers to the variety of excavation techniques which maybe employed for moving soil utilizing hand tools and/or heavy equipment as space allows. Removal andreplacement is highly effective at preventing or reducing long term exposures to soils containingunacceptable levels of lead and or arsenic, even though excavation activities may result in short termimpacts such as dust generation and disturbance to vegetation. At some properties, exterior painting maybe appropriate to encapsulate peeling or chipping lead paint which has the potential to impact the soilremedy. If smelter-related contamination exceeding soil PRGs is removed, there are no ongoingoperation or maintenance requirements which must be considered for soil removal and replacement.However, if sampling data indicate that some contamination will be left in place at depths greater than theprescribed excavation depth, there may be ongoing operation or maintenance requirements andinstitutional controls (i.e. placement of snow fence or geotextile barrier) to be considered for soil removaland replacement. Soil removal by excavation is readily implementable and is retained for furtherconsideration.

Process options for disposal of contaminated soils or wastes are onsite disposal and offsite disposal.Onsite disposal involves building a waste repository near the location of original waste generation andmoving contaminated soils to that repository. Designing and building a waste repository can be a verylong process, which lowers the short term effectiveness of this option. When construction of an onsiterepository is a viable option, it can be highly effective at reducing exposures to waste in the long term andcan be less costly than offsite disposal. Whether onsite disposal is a viable option depends on current siteownership, land use, topography, the volume of waste to be disposed of and the available area(s) onsiteappropriate for a waste repository. The former facility property which is considered the source area forthe Site is currently owned by several parties. Multiple commercial operations are located on the flat andaccessible portions of the former facility property. Remedial investigation of this property has not yetbegun, and the final fate of the waste located there is not currently known. Significant time and effortwould be required to identify an area suitable for a waste repository, and to negotiate with landowners forconsent for EPA to design and build a repository at a given location. These factors would likely preventonsite disposal from being implemented in a timely manner. For these reasons, onsite disposal of waste isnot implementable from a technical or administrative standpoint and is not retained for furtherconsideration.

Offsite disposal at a landfill is a protective option for disposing of wastes which pose an unacceptable riskto human health or the environment. Landfills may be RCRA facilities or sanitary landfills depending onthe nature of the waste to be disposed. Waste taken offsite will be managed in accordance with allapplicable federal and state requirements. Offsite disposal is an effective, proven, and reliable option forreducing human contact with soils containing unsafe levels of arsenic and/or lead. Offsite disposal isreadily implementable and is retained for further consideration.


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Two primary treatment technologies were evaluated for potential use at the Site, including chemicaltreatment (soil amendment) and physical treatment (soil tilling). The process option considered forchemical treatment is the application of phosphate soil amendments. Phosphate stabilization is aprocedure in which phosphate salts or acids are physically mixed into soil. This chemical additive canreduce the bioavailability of lead in soil below levels which are unsafe for human exposure. However,phosphate would not impact the bioavailability of arsenic or other metals in soil. Phosphate addition hasthe potential to increase the solubility of some metals, most notably arsenic, as discussed in the EPA’sJune 2015 Phosphate Amendment Fact Sheet (EPA 2015). Phosphate stabilization is moderatelyeffective and moderately implementable; however, because of the tendency to mobilize arsenic, it is notretained for further consideration.

The process option evaluated for physical treatment is soil tilling. Soil tilling involves the physicalturning over and mixing of the soil column. Tilling the surficial 12 inches of the soil column may reducesurface concentrations of arsenic and lead below risk based clean-up levels. Soil tilling with revegetationis a viable stand-alone alternative when surficial soil concentrations are close to cleanup levels andconcentrations of contaminants are much less deep in the soil column. However, soil tilling is not anoption when contaminant concentrations are similar throughout the soil column, or when very highconcentrations exist within the depth interval to be tilled. Soil tilling is typically used in large areas suchas agricultural fields where heavy equipment can maneuver easily. For small areas such as the residentialyards in OU1 of the Site, soil tilling may be impractical to implement. Soil tilling overall is considered tobe a moderately effective process option because it can be highly effective in certain cases, but ineffectivein others. Due to the small size of the majority of properties within the study area, it is not retained for usein conjunction with other approaches.

Institutional Controls (ICs) are non-engineering mechanisms which may be employed to reduce humanexposure to media of concern. ICs are not typically implemented as a stand-alone action, but aregenerally utilized together with engineering controls to form a protective remedy. The three types of ICsconsidered are governmental controls, proprietary controls, and information devices.

• Governmental controls include zoning regulations, local ordinances, building permits or otherprovisions imposed by the state or local government to restrict land or resource use and ensurethat a remedy is protective. Governmental controls are somewhat effective in reducing exposureto contamination, but they can be difficult and costly to implement over the long term.Governmental controls are generally considered appropriate as a component of the final remedyat a site. Governmental controls are not retained for inclusion in the remedial alternatives for thisearly interim action at the Site.

• Proprietary controls are established by agreements between property owners and a second (non-governmental) party to prohibit activities or future land uses that might compromise theprotectiveness of the remedy. Proprietary controls include deed restrictions, land use covenants,and conservation easements. These types of controls are moderately effective in the short andlong term, however, they are typically not practical to implement until environmentalinvestigations at the site are complete, a risk assessment has been performed, and a final remedyhas been determined. Proprietary controls are not retained for inclusion in the remedialalternatives for this early interim action at the Site.

• Informational devices provide information and educate the community about the presence ofcontamination and measures to minimize exposure. Common informational devices are deednotices, educational advisories, and tracking systems. Deed notices are non-enforceable,informational documents filed in public land records providing important information about agiven property. Educational advisories may include public health programs, community


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protective measures programs. These programs may provide the community with presentations,fact sheets, literature about lead and arsenic contamination and good housekeeping protectivemeasures, and/ or community events aimed at increasing public awareness of contamination inthe community and resources available. A public health program could also be aimed atincreasing awareness of other resources such as blood lead testing through PCCHD.Informational devices are being implemented as part of the RI and through collaborating agenciesand are not retained for possible inclusion in remedial alternatives for this early interim action atthe Site.

4.2.2. Dust

Reducing direct human contact with arsenic and/or lead contamination in indoor dust presents a uniquechallenge in that conditions vary greatly from one home to the next. Technology types and processoptions which would be unworkable to implement at one home might be the only reasonable alternative atanother. Similarly, process options which might be completely unnecessary at one home may form a keycomponent of achieving a protective remedy at another. In all cases, indoor dust cleanups can only bemoderately effective at reducing exposures in the long-term unless the potential for recontamination isaddressed (i.e. through yard soil cleanups). Containment controls and removal are the two GRAsconsidered for indoor dust.

For indoor dust, containment controls include the process options of painting walls and applying plasticsheeting. Painting walls is highly effective in the short term at reducing exposure to contaminants on thewalls. In the long term, painting is only moderately effective, as eventually the paint will begin to peeland chip, potentially exposing residents to contamination underneath. In addition, there may beadditional exposures to contamination during painting if it is not done properly. While painting may be abeneficial containment control that has a moderate cost, Superfund is unable to address contaminants thatare part of a structure or inside a building. Therefore, painting is not retained for further consideration asa component of the indoor dust remedy.

Applying plastic sheeting to create a barrier between exposed soil and living areas (for example, in asemi-finished, inhabited basement or dirt crawlspace) is an effective short term option to reduce directhuman contact with contamination inside the home. Long term effectiveness of the option will depend onthe specifics of the house in which it is utilized and how much day to day wear/disturbance the plasticsheeting must withstand. This process option may involve increased contact with exposed soil andincreased dust generation during implementation, and so is rated as moderately effective overall. Thisoption is readily implementable and relatively low cost. Application of plastic sheeting is retained forfurther consideration as a component of the indoor dust remedy.

Removal is the other engineering control considered for indoor dust. Removal of contamination fromindoor surfaces may be accomplished by cleaning contaminated surfaces or by removing and replacingcontaminated surfaces. Cleaning interior surfaces is accomplished by a variety of conventional wetcleaning techniques, including wet mopping floors, washing walls, wiping down or washing counters andfurniture, shampooing carpets, etc. and high-efficiency particulate air (HEPA) vacuuming. Cleaninginterior surfaces is highly effective in the short term, but ineffective in the long term unless measures aretaken to prevent recontamination (i.e. yard soil cleanup). Cleaning interior surfaces is readilyimplementable from both a technical and an administrative standpoint. Cleaning interior surfaces isrelatively low cost when compared to other technologies and process options for removing contaminationfrom homes. Cleaning interior surfaces is retained for further consideration as part of the indoor dustremedy.


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Removing and replacing interior surfaces is another process option for removal of contamination frominside homes. This process option includes removing and replacing contaminated carpets or otherpermeable surfaces. This option is highly effective in the short term, even though it can increase workercontact with contamination due to dust generation during implementation. In the long term, this optioncan be highly effective if the potential for recontamination is appropriately addressed through yardcleanups or other means. Replacing carpet requires coordination for disposal of contaminated materials,selection of appropriate replacement flooring, and agreement with the residents or property owners on thereplacement flooring selected. The effectiveness of this option can be increased by replacing carpet withhard surfaces such as vinyl. A separate contractor may be required for installation of replacementflooring. For these reasons, the implementability of this option is moderate. The cost of removing andreplacing contaminated interior surfaces is moderate. Removing and replacing carpet is retained forfurther consideration as a component of the indoor dust remedy.

Engineering controls such as containment, migration controls and removal of contaminated soils andcontainment and/or removal of contaminated indoor dust may be combined with appropriate treatmenttechnologies, health education and institutional controls to form the basis of a range of protectiveremedial alternatives for the Site.

5.0 Description of AlternativesIn this section describes the limited alternatives that were considered for the early interim action at thesite. These alternatives are intended to represent the realistic range of remedial options which might beemployed to address contamination in residential soils and indoor dust at the site. The risk managementsoil PRGs of 61 mg/kg for arsenic and 350 mg/kg lead have been used for the comparison of remedialalternatives. Preliminary indoor dust PRGs were established as 275 mg/kg lead and 160 mg/kg arsenic.In accordance with EPAs Guide to Preparing Superfund Proposed Plans, Records of Decision, and OtherRemedy Selection Decision Documents, three alternatives, including the “No Action” alternative, wereconsidered (EPA 1999).

For clarity, the estimated number of soil and dust cleanups proposed under each of the three alternatives issummarized below.

AlternativesIndoor Dust

CleanupSoil Removal0-12 inches

Soil Removal12-18 inches

No Action 1900 Properties 0 0 0

Alternative 2 1900 Properties 578 817 0

Alternative 3 1900 Properties 578 817 195

5.1. Alternative 1: No ActionThis alternative is included as a baseline for comparison to other alternatives. Under the no actionalternative, no steps would be taken to remediate residential soils or indoor dust within the Site. Based onresults from the first 302 properties sampled, selection of this alternative would leave lead or arsenic insoil exceeding PRGs at 133 properties. Assuming that the current sample population is generallyrepresentative of the study area as a whole, approximately 43% of the 1,900 properties in the study areaare likely to have concentrations of arsenic or lead in soil exceeding PRGs. Selection of this alternativecould be expected to leave arsenic or lead in soil exceeding clean up levels in 817 of 1,900 yards. For dustcleanups, it may leave approximately 578 homes, that is, about 30% of 1,900 properties in the study areawithout a dust cleanup.


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This alternative is readily implementable, and inexpensive. However, the no action alternative is notprotective of human health and the environment, and is therefore not effective.

5.2. Alternative 2: Soil Removal and Replacement to 12 Inches Below Ground Surface and Notto Exceed Area Remediation with Indoor Cleanups as Needed

This alternative consists of two primary components including the residential soil remedy and the indoordust remedy.

Residential Soil Remedy –

Soil removal and replacement is a three stage process involving:1. Excavation of contaminated soils,2. Disposal of excavated materials at an appropriate offsite location, and3. Replacement with clean soils. In cases where contamination that exceeds the PRGs is left in place

below the depth of the excavation, a visible barrier/marker material will be placed.

Under Alternative 2, residential soils would be evaluated and removed if concentrations exceed the PRGsfor lead or arsenic. The first step is to evaluate contamination levels down to 18 inches, and look at eacharea-weighted average contamination level at 0-1, 1-6, 6-12 and 12-18 inches. Soil cleanup will be donewhen the area-weighted average for any interval from 0-12 inches exceeds the corresponding arsenic orlead PRG. If the area-weighted average contamination level for the 12-18 inch interval exceeds the leador arsenic PRG, a barrier (geotextile or snow fence) would be placed at the bottom of the 12 inchexcavation prior to covering the area with clean soils. Play areas and gardens are initially included in thearea-weighed averaging but are also evaluated separately when comparing to PRGs. If the measured soilconcentration in a garden or play area exceeds the PRGs at any depth, soils in that DU will be removeddown to the depth of contamination or up to 24 inches. Based on data to date, approximately 817 yardsout of 1,900 properties may require cleanup to 12 inches.

In addition, hotspots, or any DU having soil concentrations greater than the not to exceed (NTE) values of1,000 mg/kg arsenic or 1,918 mg/kg lead at any depth sampled, will be removed to a maximum depth of18 inches. Based on data to date, approximately 5-6 yards out of 1,900 properties may require a hotspotcleanup; however, these properties may be cleaned up anyway due to the yard average concentrationsexceeding the PRG. Subsurface soils between 12 inches below ground surface and 18 inches belowground surface with whole-yard area-weighted average concentrations that exceed the PRG but are lessthan the NTE would remain in place. A visible barrier also will be placed at the final excavation level of18 inches for NTE DUs, or 24 inches for gardens and play areas, if confirmation soil sample results aregreater than PRGs. Residents and property owners will receive a cleanup completion letter, which willdescribe the work done, whether any contamination exceeding the PRGs or Not to Exceed (NTE) levelswas left in place for any portion of the yard, the yard restoration requirements and warranty period fornew grass, trees, shrubs, other vegetation and landscaping materials, and recommendations orrequirements, if needed, to maintain long-term protectiveness of the cleanup. Institutional controls will beneeded for properties where waste is left in place above levels safe for unlimited use and unrestrictedexposure. The need for ICs at specific properties and what kind of ICs may be needed will be developedduring implementation of the early interim action residential property cleanups, and the public will havean opportunity to review and comment on that portion of the remedy as part of the final ROD for OU1.Institutional controls developed for OU1 will comply with the Colorado Environmental Covenant Statute,C.R.S. §§ 25-15-317 et seq.”

Indoor Dust Remedy – Accessible indoor dust may be remediated if it exceeds the chronic minimum risklevel (MRL) for arsenic (ATSDR 2016) or public health action levels, specifically childhood lead


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exposure intervention levels (American Academy of Pediatrics 2013). Indoor dust cleanups may benecessary at a small percentage of homes where outdoor soil concentrations do not require cleanup. It isestimated that an indoor dust cleanup will be required at approximately 30% of the properties in the studyarea, which equates to 578 homes. Figure 5-1 presents a flow diagram of the Alternative 2 decisionmaking process.

5.3. Alternative 3: Soil Removal and Replacement to 18 Inches Below Ground Surface withIndoor Cleanups as Needed

This alternative consists of two primary elements, including residential soil remedy and the indoor dustremedy.

Residential Soil Remedy –

Soil removal and replacement is a three stage process involving:1. Excavation of contaminated soils,2. Disposal of excavated materials at an appropriate offsite location, and3. Replacement with clean soils. In cases where contamination that exceeds the PRGs is left in place

below the depth of the excavation, a visible barrier/marker material will be placed,

Under Alternative 3, residential soils would be evaluated and removed if concentrations exceed the PRGsfor lead or arsenic. The first step is to evaluate contamination levels down to 18 inches, and look at eacharea-weighted average contamination level at the different sampling intervals, that is, 0-1, 1-6, 6-12, and12-18 inches. Soil cleanup will be done where the area-weighted average for any interval from 0-18inches exceeds the corresponding arsenic or lead PRG. For properties where the area-weighted averagecontamination level for any of the sampling intervals above 12-18 inches require cleanup, but the 12-18inch interval does not, excavation would extend only to 12 inches.

For properties where the area-weighted average contamination level for the 12-18 inch interval exceedsthe PRGs, excavation would extend to 18 inches. In addition, confirmation sampling would be performedat the 18 inch depth and a visible barrier (geotextile or snow fence) would be placed where concentrationsstill exceed PRGs. Play areas and gardens are initially included in the area-weighted averaging but arealso evaluated separately when comparing to PRGs. If gardens or play areas exceed the PRGs at anydepth, soils in those DUs will be removed down to the depth of contamination or up to 24 inches. Thisalternative would result in removing all soil from the 817 yards removed under Alternative 2, as well as195 yards needing an additional 6 inches of soil cleanup from 12 to 18 inches.

In addition, hotspots, or any DU having soil concentrations greater than the NTE values of 1,000 mg/kgarsenic or 1,918 mg/kg lead will be removed to a maximum depth of 18 inches. Based on data to date,approximately 5-6 yards out of 1,900 properties may require a NTE cleanup; however, these propertiesmay be cleaned up anyway due to the yard average concentrations exceeding the PRG. Individual yardcomponents other than gardens and play areas with subsurface soils that exceed the PRG for arsenic orlead but are less than the respective NTE would remain in place. A visible barrier also will be placed atthe final excavation level of 18 inches for NTE DUs, or 24 inches for gardens and play areas, ifconfirmation soil sample results are greater than PRGs. Residents and property owners will receive acleanup completion letter, which will describe the work done, whether any contamination exceeding thePRGs or Not to Exceed (NTE) levels was left in place for any portion of the yard, the yard restorationrequirements and warranty period for new grass, trees, shrubs, other vegetation and landscaping materials,and recommendations or requirements, if needed, to maintain long-term protectiveness of the cleanup.Institutional controls will be needed for properties where waste is left in place above levels safe forunrestricted use and unlimited exposure. The need for ICs at specific properties and what kind of ICs may


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be needed will be developed during implementation of the early interim action residential propertycleanups, and the public will have an opportunity to review and comment on that portion of the remedy aspart of the final ROD for OU1. Institutional controls developed for OU1 will comply with the ColoradoEnvironmental Covenant Statute, C.R.S. §§ 25-15-317 et seq.”

Indoor Dust Remedy – Accessible indoor dust may be remediated if it exceeds the chronic minimum risklevel (MRL) for arsenic (ATSDR 2016) or public health action levels, specifically childhood leadexposure intervention levels (American Academy of Pediatrics 2013). Indoor dust cleanups may benecessary at a small percentage of homes where outdoor soil concentrations do not require cleanup. It isestimated that an indoor dust cleanup will be required at approximately 30% of the properties in the studyarea, which equates to 578 homes. Figure 5-2 presents a flow diagram of the Alternative 3 decisionmaking process.

6.0 Individual and Comparative Analysis of AlternativesThe purpose of this section is to present relevant information necessary for decision makers to select aninterim remedy for the Site. To comply with the EPA’s Guidance for Conducting RemedialInvestigations and Feasibility Studies Under CERCLA (EPA 1988), the selected alternative should:

• Be protective of human health and the environment,

• Attain ARARs or provide grounds for invoking a waiver,

• Utilize permanent solutions and alternative treatment technologies or resource recoverytechnologies to the maximum extent practicable,

• Satisfy the preference for treatment that reduces the mobility, toxicity, or volume of waste as aprinciple element or provide an explanation in the ROD as to why not,

• Be effective in the short-term,

• Be implementable,

• Cost effective,

• Acceptable to the State,

• Acceptable to the community.

The detailed analysis of alternatives provides the basis for selecting the remedy by evaluating eachalternative against these nine criteria. The results of the detailed analysis of alternatives will support thefinal selection of a remedial action.

6.1. Alternative 1: No ActionThis alternative is included as a baseline for comparison to other alternatives. Under the no actionalternative, no steps would be taken to remediate residential soils or indoor dust within the Site. The noaction alternative is not protective of human health and the environment, and is therefore removed fromfurther consideration.

6.2. Alternative 2: Soil Removal and Replacement to 12 Inches Below Ground Surface and Notto Exceed Area Remediation with Indoor Cleanups as Needed


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Alternative 2 provides for removal of soil from the upper 12 inches below ground surface, and hotspotremoval down to 18 inches below ground surface if concentrations exceed the NTE values. The EPASuperfund Lead-Contaminated Residential Sites Handbook (Lead Handbook) suggests that 12 inches ofclean replacement fill is typically sufficient to prevent direct exposure (EPA, 2003). The rationale behindthis is that with the exception of gardening, the typical activities of children and adults in residentialproperties do not extend below 12 inches below ground surface.

This alternative can accomplish the Site RAOs and is protective of human health and the environment,satisfying the first threshold criterion. The other threshold criterion considered in the detailed analysis ofalternatives is compliance with ARARs. Alternative 2 complies with, or waives, ARARs. Long termeffectiveness of Alternative 2 is considered moderate to high, because it complies with the LeadHandbook. Although there is some residual risk due to the possibility that arsenic or lead contaminationleft in place between the 12- and 18-inch horizons could migrate upwards as a result of freeze thaw cyclesor human activity in yards, the risk is considered low due to the limited exposure time to these deepersoils. The removal and replacement of contaminated surficial yard soils only partially satisfies theregulatory preference for remedies which reduce the toxicity, mobility, or volume of contaminantsthrough permanent solutions or alternative treatments. Alternative treatments such as phosphateamendments were considered, but not retained due to technical limitations of the treatments and thepresence of both lead and arsenic in soil. For example, lead could potentially be immobilized throughphosphate treatment of the soils; however, phosphate treatment also increases the potential for leaching ofarsenic from the soils. Therefore, treatment of soils was not selected as part of Alternative 2. Short termeffectiveness of soil removal and replacement with indoor dust cleanups as necessary is high, as theremedy requires relatively little time to implement. However, there will be some dust generation andpotential for worker exposure during the removal action. Estimated costs for implementation ofAlternative 2 are detailed in Table 6.1.

State and community acceptance will be assessed following comments on the proposed plan.

6.3. Alternative 3: Soil Removal and Replacement to 18 Inches Below Ground Surface withIndoor Cleanups as Needed

Alternative 3 provides for removal of soil exceeding PRGs to the full sampled depth of 18 inches. TheEPA Lead Handbook identifies that the additional cleanup costs may be balanced by reductions in futurehealth education, maintenance, and monitoring costs. Full depth removal may also prevent the need forplacing subsurface barriers or markers, or for obtaining environmental covenants or easements. Fullremoval down to 18 inches normally allows the remediated yard to return to unrestricted use (EPA 2003).

This alternative can accomplish the Site RAOs and is protective of human health and the environment,satisfying the first threshold criterion. The other threshold criterion considered in the detailed analysis ofalternatives is compliance with ARARs. Alternative 3 can be implemented in compliance with ARARs.Long term effectiveness of Alternative 3 is considered high. The removal and replacement ofcontaminated yard soils only partially satisfy the regulatory preference for remedies which reduce thetoxicity, mobility, or volume of contaminants through permanent solutions or alternative treatments.Alternative treatments such as phosphate amendments were considered, but not retained due to technicallimitations of the treatments and the presence of both lead and arsenic in soil. Soil removal andreplacement with indoor dust cleanups as necessary is highly effective in the short term, as the remedyrequires relatively little time to implement. However, there will be some dust generation and potential forworker exposure during the activity. Estimated costs for implementation of Alternative 3 are detailed inTable 6.1.

State and community acceptance will be assessed following comments on the proposed plan.


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6.4. Comparative AnalysisTable 6.2 presents a summary of the alternatives evaluation against the nine criteria. The EPA will selectthe best alternative and carry it forward in the Proposed Plan and Interim ROD for the Site.

7.0 References

Agency for Toxic Substances and Disease Registry (ATSDR), 2016. Technical Assistance for

Lead and Arsenic in Indoor Dust Related to Colorado Smelter NPL Site, Pueblo, Colorado.

May. [Appendix F]

American Academy of Pediatrics, 2013. Recommendations on Medical Management of

Childhood Lead Exposure and Poisoning. July.

American Society for Testing and Materials, 1994. Standard Practice for Collection of Floor

Dust for Chemical Analysis. D5438-11. September.

Colorado Department of Public Health and Environment (CDPHE), 2011. Analytical Results

Report, Colorado Smelter, Pueblo, Colorado. June. CON000802700.

Pacific Western Technologies (PWT), 2015a. Uniform Federal Policy (UFP) Quality Assurance

Project Plan for Demonstration of Methods Applicability at Colorado Smelter. Rev. 2.

Document Control Number WA136-RICO-08UA DMA. May 8.

PWT, 2015b. UFP Quality Assurance Project Plan for Remedial Investigation at Colorado

Smelter. Revision 0. Document Control Number WA136-RICO-08UA OU1 RI UFP QAPP.

November.

PWT, 2016a. UFP Quality Assurance Project Plan for Remedial Investigation at Colorado

Smelter, Rev. 3. Document Control Number WA136-RICO-08UA OU1 RI UFP QAPP.

April.

PWT, 2017a. Bioavailability Technical Memorandum, Revision 1 – Colorado Smelter

Superfund Site, Pueblo, Pueblo County, Colorado. June. [Appendix D]

PWT, 2017b. Technical Memorandum - Site-Specific Soil-to-Dust Mass Transfer Ratio (MSD)

Calculation, Revision 1, Colorado Smelter Superfund Site, Pueblo, Pueblo County,

Colorado. May.

PWT, 2017c. Technical Memorandum Preliminary Identification of Chemicals of Potential Concern.May. [Appendix A]

PWT, 2017d. Technical Memorandum Preliminary Remediation Goals for Soil, Revision 2. June.[Appendix B]


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Smith, D. B., Cannon, W.F., Woodruff, L.G., Solano, F., Kiburn, J.E., and Fey, D.L., 2013.Geochemical and Mineralogical Data for Soils of the Conterminous United States. U.S.Geological Survey Data Series 801. 19 p.

United States Environmental Protection Agency (EPA), 1988. Guidance for Conducting RemedialInvestigations and Feasibility Studies under CERCLA (EPA/540/G-89/004).

EPA, 1999. Guide to Preparing Superfund Proposed Plans, Records of Decision, and Other RemedySelection Decision Documents.

EPA, 2003. Superfund Lead-Contaminated Residential Sites Handbook. (OSWER 9285.7-50).August.

EPA, 2006a. Guidance on Systematic Planning Using the Data Quality Objectives Process. EPAQA/G-4. EPA/240/B-06/001. February. http://www.epa.gov/quality/qs-docs/g4-final.pdf

EPA, 2006b. Air Quality Criteria for Lead Final Report. Volume 1, page 3-21. EPA/600/R-05/144aF-bF. November. https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=158823

EPA, 2013. Integrated Science Assessment (ISA) for Lead (Final Report). Washington, DC,EPA/600/R-10/075F, July.

EPA, 2015. Scheckel, K.G., Diamond, G., Maddaloni, M., Partridge, C., Serda, S., Miller,

B.W., Klotzbach, J. and Burgess, M. 2013. Amending soils with phosphate as means to

mitigate soil lead hazard: A critical review of the state of the science. J. Toxicol. Environ.

Health B 16(6): 337–380.

EPA, 2016a. Evaluation of the Contribution of Outdoor Lead in Soil to Indoor Lead in Dust at

Colorado Smelter Superfund Site. June. [Appendix E]

EPA, 2016b. Action Memorandum – Approval and Funding for an Emergency Removal Action

Involving the Cleanup of Lead-Contaminated Indoor Dust in Residential Areas of Pueblo,

CO, as a result of Smelting Activities at the Colorado Smelter Site. July. [Appendix C]

EPA, 2016c. Office of Land and Emergency Management (OLEM) Directive (#9200.2-167).

December.

EPA, 2017. EPA Region 8 Colorado Smelter Lead Consultation Technical Review Workgroup

For Lead Documentation, May 5.

http://www.epa.gov/quality/qs-docs/g4-final.pdf

https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=158823

Colorado Smelter OU1 Focused Feasibility Study Report, Revision 3

June30, 2017

Figures

Sources: Esri, HERE, DeLorme, USGS, Intermap, INCREMENT P, NRCan,Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand),MapmyIndia, NGCC, © OpenStreetMap contributors, and the GIS UserCommunity

PATH: K:\GIS Library\Projects\Colorado Smelter\Maps\Figure_1.1_General_Site_Location_20170601.mxd

Colorado SmelterOU1 Site Location

Colorado

FIGURE 1-1Colorado Smelter OU1

Site Location

³Projection: NAD 1983 StatePlane Colorado South FIPS 0503 Ft USImage: ESRI 2014

Data: City and County of PuebloSource: Focused Feasibility Study

Pueblo

0 21 Miles

Map Created: 6/01/2017Map Created By: DM

Pueblo Wes t

McCulloch Blvd

La1<e ueb o

q,

l 1 :

I I

I ~-/

Lahe PU(>blo State Park

~<,,, ... ....

E Platteville Blvd

Goodnight Ave

W 11th St

Puabb C,tyPark Poobb

Zoo

Bridle Tr\ fan1baug'I Ln

0

. i . i f u

w20;s1 ,. "' i

W 24th St .;; g •

W181hSt W 171h St :

0

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Lakeview Ave

I W Northern Ave

""" ' , .. ,.,

M•nn• a Inclan,;, Av

I

""'

-~

Walk.-.g Std Golf

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Cobtad:> State UnP-Jers1ty•Puebb

Roael~·n Cermte,y

•

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µ0 1,000500 Feet

NAD 1983 StatePlane Colorado South FIPS 0503 FeetImagery: Google Earth dated August 2013

Data: City and County of PuebloSource: Focused Feasibility Study

Legend Sampled PropertiesColorado Smelter Superfund Site OU1

Figure 1-2

Soil Sampled Only

Smelter Site Boundary

Preliminary Study Area

Dust and Soil Sampled

Map Created: 6/01/2017Map Created By: DM

Path: K:\GIS Library\Projects\Colorado Smelter\Maps\Figure_1.2_Sampled_Properties_Res_Soil_Indoor_Dust_20170601.mxd

CJ 1111

·- - ' D r=>Vv"'T PACIFICWESTERNTI".CHNOLOGIES,LTD. @ " .

2016-2017 Early Action Indoor DustEmergency Removal ResponseLegendColorado Smelter Superfund Site OU1

Figure 1-3

µ0 1,000500 Feet

NAD 1983 StatePlane Colorado South FIPS 0503 FeetImagery: Google Earth dated August 2013

Data: City and County of PuebloSource: Focused Feasibility Study Map Created: 6/01/2017

Map Created By: DM

Smelter Site Boundary

Preliminary Study Area

Accelerated Indoor DustRemediation Property

Path: K:\GIS Library\Projects\Colorado Smelter\Maps\Figure_1.3_2017_Early_Action_Indoor_Dust_20170608.mxd

1111 D .. , L ,

r->~T PACIFICWESTERNTECHNOLOGIES,LTD

Revision Date: 6/1/2017Focused Feasibility StudyFIGURE 2-1

COLORADO SMELTER OPERABLE UNIT 1Conceptual Site Model Revision: 1

Author: MUChecked: SS

ForMer Qnci current Qlr/wlnci dispersion

/ M~ / - ----i r- - ~

~orMer 7": 1 I I I I Coloro.do I 1 I I I I \./Qste piles

Tro.nsport of slo.g to neighborhoods o.s fill

o.s

SMel ter eMlsslons In soil

SM el ter \./Qste piles

ForMer stQck eMlsslons

Leo.d po.Int In soil

Residentio.l neighborhoods

Canto.Mino. tlon froM leo.d pipes

I _ ____,....__

Canto.Mino. tlon brought Inside by pets

AutoCAD SHX Text

Former and current air/wind dispersion

AutoCAD SHX Text

Waste piles

AutoCAD SHX Text

Former Colorado Smelter

AutoCAD SHX Text

Former stack emissions

AutoCAD SHX Text

Residential neighborhoods

AutoCAD SHX Text

Transport of slag to neighborhoods as fill

AutoCAD SHX Text

Peeling lead paint

AutoCAD SHX Text

Lead paint in soil

AutoCAD SHX Text

Contamination brought inside by pets

AutoCAD SHX Text

Contamination from lead pipes

AutoCAD SHX Text

Slag used for Driveways

AutoCAD SHX Text

Slag used as fill material

AutoCAD SHX Text

Waste piles

AutoCAD SHX Text

Smelter emissions in soil


June 30, 2017


Alternative 2

, "'I r "'I Is the area-

Is the area-weighted average

Yes weighted average concentration for Yes 0-1, 1-6, or6-12 - concentration for

12-18 inches inches above the

above the PRG? PRG?

\... '-No Nol

Excavate the entire Excavate the entire property to 12

property to 12 inches depth and inches depth place a barrier at 12

inches.

, I" "" I" "'I

Is the

Does the property Yes concentration of a Excavate garden or

garden or play Yes play area DUs have a garden or

area DU above exceeding PRG to play area DU?

the PRG at any 24 inches depth. depth?

'-- \... No No I

r 'I Is the

concentration of Yes Excavate those any DU and depth ~ DUs to 18 inches exceed the NTE depth . !

PRG? \,. .J

Cover any No excavated areas - with clean soil and

revegetate.

Equation for calculation of area-weighted average concentration:

Where

(Cvu1 XAuu1 +CvLuXAuu:L+···+Cvun XAvun) (Am11 +Am12+···+Aoun)

CAA= the area-weighted average concentration for a property with n DUs Coux = the concentration of the DU, where Xis 1, 2, etc. up ton Aoux = the surface area of the DU, where X is 1, 2, etc. up to n


June 30, 2017


Alternative 3

, "'I /' "'I Is the area- Is the area-

Excavate the entire property to 18

weighted average Yes weighted average 1

Yes • inches depth and concentration for . concentration for

collect confirmation any depth above 12-18 inches

samples at 18 inch the PRG? above the PRG?

depth. \... ./ \. ./

No No 1 ! / "I

Are the

Excavate the entire confirmation Yes property to 12 sample ~

inches depth concentrations above the PRG?

\.. .)

Nol

, ....... , "'I Is the

Does the property concentration of a Excavate garden or

Yes garden or play Yes play area DUs have a garden or .

area DU above 1-----+

exceeding PRG to play area DU?

the PRG at any 24 inches depth.

\. \. depth?

./

No No I I r "I

Is the concentration of Yes Excavate those

any DU and depth - DUs to 18 inches above the NTE depth. ! PRG?

\... ./

No Cover any excavated areas

with clean soil and revegetate.

Equation for calculation of area-weighted average concentration:

Where

C . = (Cou1 XADu1 + Cou2XADu2+ .. ·+CounXADu,i) AA (Avu1 +Anu2+ .. ·+Avun)

CAA= the area-weighted average concentration for a property with n DUs Coux = the concentration of the DU, where Xis 1, 2, etc. up ton Aoux = the surface area of the DU, where X is 1, 2, etc. up to n

Place a barrier at 18 inches.

I


June 30, 2017

Tables

Colorado Smelter OU1 Focused Feasibility Study Report

June 30, 2017

Table 2.1 Preliminary PRGs for Colorado Smelter OU1

COPCRSL

(mg/kg)Chronic Exposure PRG

(mg/kg) aAcute Exposure PRG

(mg/kg) b

Antimony 39 48 NA d

Arsenic c 0.68 61 1,000

Cadmium 160 100 43,000

Cobalt 23 36 NA

Copper 3,100 4,800 1,200

Lead 400 350e 1,918

Manganese 1,800 2,800 NA

Nickel 1,500 2,400 280,000

Thallium 0.78 1.2 NA

Vanadium 390 600 NA

Zinc 23,000 36,000 NA

Notes:a PRG is intended for comparison with area-weighted average concentrations for each property.b PRG is intended as a not-to-exceed value for a specific DU and depth.c Arsenic PRG range is based on the risk management range and backgroundd Calculated RBC exceeds the highest physically possible concentration of 1,000,000 mg/kge The Chronic Exposure PRG for lead is lower than the RBC of 740 mg/kg and was selected based

on a risk management decision.COPC Contaminant of potential concernPRG Preliminary remediation goalRSL Regional Screening Level

Table 3.1State and Federal Applicable or Relevant and Appropriate Requirements


June 30, 2017 Page 1 of 8

ARARType

AuthorityMedium/Activity

Citation Status Synopsis of RequirementAction to be Taken toAttain Requirement

SURFACE WATERChemical-specific

StateRegulatoryRequirement

DischargeWater

ColoradoDischargePermit SystemRegulations, 5CCR 1002-61,RegulationNo. 61, pursuantto CRS § 25-8-501 to 509

Applicable Establishes program forpermitting discharges ofcontaminants into watersof the United Stateswithin Coloradoincluding discharges ofstormwater duringconstruction activities.

The substantiverequirements of theseregulations will be metfor any potentialstormwater dischargesduring construction.Under Section 121(e)(1)of CERCLA a permit isnot required.

Action-specific StateRegulatoryRequirement Discharge

Water

Colorado WaterQuality ControlActStormwaterDischargeRegulations, 5CCR 1002.2

Applicable Establishes stormwatercontrol requirementsfor constructionactivities.

Potentially applicable ifconstruction activitiesinvolve stormwaterdischarges as part of theremedial action.

Location-specific FederalRegulation

Wetlands Clean Water ActSection 404(33 USC 1251, etseq; 40 CFR 230,231)

Applicable Requires Federalagencies to avoid, to theextent possible, adverseimpacts associated withdestruction or loss ofwetlands. Regulates thedischarge of dredged orfill material into watersof U.S. Consultation withthe Regional ResponseTeam required.

Wetlands may be presentin OU1. Regulations areapplicable only ifremedial activitiesimpact the wetlandsareas. Remedial designwill avoid, to the extentpossible, impacts to anywetlands, if present.

Location-specific FederalExecutiveOrder andRegulation

Wetlands (i) ExecutiveOrder No. 11990Protection ofWetlands

(i) TBC Requires Federalagencies to avoid, to theextent possible, theadverse impactsassociated with the

If wetlands are presentand impacted, mitigationactions will beconducted.




ARARType



destruction or loss ofwetlands. The ExecutiveOrder is TBC because itis not a promulgatedregulation. Nonetheless,EPA is required tocomply with theExecutive Order.

Location-specific FederalExecutiveOrder andRegulation

Floodplains (i) ExecutiveOrderNo. 11998FloodplainManagement

(i) TBC Requires Federalagencies to evaluate thepotential effects ofactions they may take ina floodplain to avoid, tothe extent possible, theadverse impactsassociated with direct andindirect development of afloodplain.

Remedial design willavoid, to the extentpossible, impacts to anyfloodplains, if present.

AIRAction-specific State

RegulatoryRequirement

Construction Colorado AirQuality ControlAct(5 CCR § 1001-1, 2, 3, 4, 5, 8,10)

Applicable Establishes emissionsstandards for PM10 andlead. Pursuant to theColorado Air PollutionPrevention and ControlAct, applicants forconstruction permits arerequired to evaluatewhether the proposedsource will exceedNAAQs. Applicants arealso required to evaluatewhether the proposedactivities would cause the

Compliance withapplicable provisions ofthe Colorado Air Qualityrequirements will beachieved by adhering toa fugitive emissionscontrol plan prepared inaccordance withRegulation No. 1. Theremedial actionsconsidered in this FFSare not expected toexceed the emissionlevels for lead, although




ARARType



Colorado ambientstandard for PM10 to beexceeded. Coloradoregulates fugitiveemissions throughRegulation No. 1.Regulation 8 setsemission limits for lead.Applicants are requiredto evaluate whether theproposed activities wouldresult in the Regulation 8lead standard beingexceeded.

some lead emissionsmay occur. Compliancewith Regulation 8 will beachieved by adhering toa fugitive emissionscontrol plan prepared inaccordance withRegulation No. 1. Thesubstantive requirementsof Regulation 3 arepotentially applicable.

Action-specific StateRegulatoryRequirement

Construction ColoradoFugitive DustControlPlan/Opacity,Regulation No.1., 5 CCR 1001-3, pursuant toColorado AirPollutionPrevention andControl Act,CRS § 25-7-101et. seq.

Applicable Establishes regulationsconcerning fugitiveemissions fromconstructionactivities, storage andstockpiling activities, andhaul trucks.

Dust suppression will beused as needed duringconstruction andmaintenance of theremedy.


Construction Colorado AirPollutionPrevention andControl Act,APENs

Applicable Establishes emissionscontrol regulations forconstruction ormodification ofstationary

Substantive requirementsof an Air PollutionEmission Notice (APEN)are applicable if theremedial actions disturb




ARARType



Regulation No.3, 5 CCR 1001-5,Regulation 3

sources. contaminated soil. AnAPEN will be filed,although under Section121(e)(1) underCERCLA a permit is notrequired.


Construction Colorado AirPollutionPrevention andControl Act,Odors,Regulation No.2, 5 CCR 1001-4

ApplicableApplies to any remedialaction that may createregulated odors; e.g.,diesel equipment

Planned remedial actionsare not expected tocreate regulated odors.

SOLID AND HAZARDOUS WASTE MANAGEMENTAction-specific State


HazardousWaste

ColoradoHazardousWasteRegulations, 6CCR 1007-3,Part264: Section264.301, (g), (h),(i) and (j);Section 264.310(a)(1)through (a)(4);Section 264.310,(b)(1) and (b)(5)

Applicable Specific provisions ofSection 264.301 concernrun-on control, run-offcontrol, management ofrun-on and run-offcontrolsystems and winddispersal. Specificprovisions of Section264.310 concernplacement of a cover tominimize infiltration,minimize maintenance,promote drainage andminimize erosion andaccommodate settling.

These specific provisionsof the hazardous wasteregulations may berelevant and appropriatein certain circumstancesdepending on sitespecific conditions (e.g.,if hazardous waste isencountered). Thedetermination of whethersuch requirementswill be both relevant andappropriate to theactivities to beundertaken in OU1 willbe based on bestprofessional judgmentand isconducted on a site




ARARType



specific basis taking intoaccount the physicalnature and location ofthe media involved,whether therequirements are wellsuited to the siteconditions, and otherfactors.

Action-specific FederalRegulation

HazardousWaste

HazardousMaterialsTransportationAct, Regulations,49 USC Sect.1801 - 1813, 49CFR Parts 107,171-177

Comply with offsiterequirement

Regulates transportationof hazardousmaterials.

Applicable only if theremedial action involvesoff-site transportation ofhazardous materials. Theregulations affectingpackaging, labeling,making, placarding,using proper containers,and reporting dischargesof hazardous materialswould be potentialARARs.

MINING RECLAMATIONAction-specific State


Soil ColoradoNoxious WeedAct andregulations, CRS§ 35-5.5-101-119; 8 CCR1203-19

Applicable Colorado regulationsaddressing managementof noxious weeds.

Revegetated areas andother areas impacted bythe cleanup will bemonitored for thepresence of noxiousweeds and weedmanagement will beused if needed.

ENVIRONMENTAL COVENANTS




ARARType



Location-specific State StatutoryRequirement

Sitewide ColoradoEnvironmentalCovenants, CRS§§ 25-15-317 etseq

Applicable Requires environmentalcovenants (ECs) or noticeof environmental userestrictions (RNs)whenever residualcontamination is left inplace at properties and atlevels above unlimiteduse and unrestrictedexposure or anengineered feature orstructure that requiresmonitoring,maintenance, oroperation is included inthe remedy.

The substantiveprovisions of CRS §§25-15-317, et seq. areARARs. Creation of alegal EC or RN isdependent oncompliance withprocedural oradministrative provisionsand the discretion ofCDPHE. CDPHE statesthrough concurring onthis Interim ROD that ifthe EC or RN presentedto CDPHE foracceptance or approvalincludes the Land UseRestrictions set forth inthis Interim ROD, issigned or approved bythe landowner, andfollows the provisions ofthe ColoradoEnvironmental CovenantStatute, CDPHE willaccept the EC. Further,CDPHE states throughconcurrence on thisInterim ROD that ECsand RNs will only bemodified or terminatedto reflect changes madeto the Superfund remedy.




ARARType



NOISE CONTROLAction-specific State Construction Colorado Noise

AbatementStatute, CRS §§25-12-101-109

Applicable Establishes maximumpermissible noise levelsfor particular timeperiods and land usezones.

Noise restrictions will befollowed as neededduring construction andmaintenance of theremedy.

HISTORIC AND CULTURAL RESOURCES

Location-specific State Construction ColoradoHistorical,Prehistorical, andArchaeologicalResources Act,ColoradoRevisedStatutes (CRS)§§24-80-401 to411,24-80-1301 to1305

Applicable Establishes proceduresand requires a permit forinvestigation, excavation,gathering, or removalfrom the natural state ofanyhistorical, prehistorical,or archaeologicalresources on state landsfor the benefit ofrecognized scientific oreducational institutions.Also requires anexcavationpermit and notification ifhuman remains are foundon state land.

May be applicable ifarchaeological resourcesare removed or humanremains discoveredduring remedialactivities; coordinationwith statearchaeologist required,but no permit is neededwithin the Superfundsite.

Location-specific State Construction ColoradoRegister ofHistoric Places,CRS §§ 24-80-101 to108

Applicable Establishes requirementsfor protecting propertiesof historical significance.

May be applicable ifremedial actions impactany property listed onthe Register of HistoricPlaces.

Location-specific FederalExecutiveOrder and

Construction (i) ExecutiveOrderNo. 11593

TBC Requires federal agenciesto institute procedures toensure programs

May be applicable ifremedial actions impactany property affected by




ARARType



Regulation Protection andEnhancement ofthe CulturalEnvironment;(ii) 16 USC 470

contribute to thepreservation andenhancement of non-federally owned historicresources. Consultationwith the AdvisoryCouncil on HistoricPreservation required.

this regulation.


Construction National HistoricPreservation Act(NHPA), 16USC § 470 etseq.; 40 CFR §6.301(b); 36CFR Part 63,Part 65, Part 800

Applicable Expands historicpreservation programs tominimize harm toNational HistoricLandmarks;requires preservation ofresources included in oreligible for listing on theNational Register forHistoric Places (NRHP).

May be applicable ifremedial actions impactany property affected bythis regulation.


Construction The Historic andArchaeologicalDataPreservation Actof 1974, 16 USC469 40 CFR §6.301(c)

Applicable Establishes procedures topreserve historical andarcheological data thatmight be destroyedthrough alteration ofterrain as a result of afederal constructionproject or a federallylicensed activityprogram.

Remedial Activities mayaffect historical and/orarcheological data. Acultural resources surveywill be performed toidentify and evaluate allhistoric properties, ifany, which may beaffected by remedialactivities.

Table 4.1

Evaluation of General Response Actions and Process Options for Residential Soil

General Response

Actions for Residential

Soil

Remedial Technology

Types (For General

Response Actions)

Process Options

Short and Long

-Term

Effectiveness

ImplementabilityRelative

CostOption Retained?

Soil cover Moderate Low Moderate No

Soil-clay cover Moderate Low Moderate No

Asphalt cover High Low High No

Concrete cover High Low High No

Synthetic membrane High Low High No

Migration Controls Surface ControlsGrading, revegetation,

erosion controlsLow Moderate Moderate

Retained for use in

conjunction with other

process options

ExcavationConventional earth

movingHigh High Moderate Yes

On-Site DisposalConstruct on-site waste

repositoryModerate Low Low No

Off-Site DisposalDispose at appropriate

landfillHigh High Moderate Yes

Chemical Treatment Soil amendments Moderate Moderate Low No

Soil Removal /

Replacement

Containment Controls Engineered Cover


June 30, 2017

Physical Treatment Soil tilling Moderate Moderate Low No

Soil Treatment


June 30, 2017

Table 4.2

Evaluation of General Response Actions and Process Options for Indoor Dust

General Response

Actions for Indoor Dust

Remedial Technology

Types (For General

Response Actions)

Process Options

Short and Long

-Term

Effectiveness

ImplementabilityRelative

CostOption Retained?

Wet mopping floors Moderate High Low

Retained for use in


process options

Washing walls Moderate High Low

Retained for use in


process options

Vacuuming carpets Moderate High Low

Retained for use in


process options

Replace interior

surfaces

Remove and replace

flooringHigh Moderate Moderate

Retained for use in


process options

Painting Walls,

windowsills, etcModerate High Moderate

Retained for use in


Clean interior surfaces

Removal


June 30, 2017

windowsills, etcModerate High Moderate conjunction with other

process options

Install Plastic sheeting Moderate High Low

Retained for use in


process options

Cover interior surfacesContainment


June 30, 2017

Table 6.1

Colorado Smelter Superfund Site; Operable Unit 1

Comparison of Total Cost of Remedial Alternatives

Site: Colorado Smelter Operable Unit 1 Base Year: 2017

Location: Pueblo County, Colorado

Phase: Comparative Analysis if Remedial Alternatives

Alternative 1 Alternative 21,3 Alternative 32,3

No Action

12-inch Soil Removal at 817

Properties and Indoor Dust

Cleanup at 578 Properties

12-inch Soil Removal at 622

Properties, 18-inch Soil at 195

Properties and Indoor Dust

Cleanup at 578 Properties

Duration 0 9 9

Capital Cost $0 $41,196,100 $43,828,600

Annual O&M Cost $0 $1,792,000 $1,792,000

Total Constant Dollar Cost $0 $42,987,270 $45,619,770

Total Present Value of Alternative

(assuming 7% discount factor) $0 $34,371,000 $36,463,000

Present Value of Alternative Range

(assume accuracy of estimate -30%

+50%) $0

$24,059,700 to

$51,556,500

$25,524,100 to

$54,694,500

Notes:1Alternative 2: The 9-year duration, assumes 12-inch soil removal at 817 properties and dust cleaning at 578 properties.2Alternative 3: The 9-year duration, assumes soil removal of 12-inch at 622 properties and 18-inch at 195 properties, and dust cleaning at 578 properties.3Cost details in 2016 dollars for a typical 5,000 square foot property undergoing 12- and 18-inch soil removals

and dust cleaning for a typical 1,500 square foot house plus basement are tabulated in Appendix H.

DESCRIPTION

6/13/2017Pacific Western Technologies, Ltd.

Page 1 of 1

Table 6.2

Summary of Remedial Alternative Evaluation Criteria

Criterion Description

1

No Action

2

(Soil Removal to 12")

3

(Soil removal to 18")

Overall Protection of

human health and

the environment

Does an alternative

eliminate, reduce or control

threats to public health and

the environment through

ICs, engineering controls, or

treatment?

Not

ProtectiveProtective Protective

Compliance with

ARAR's

Does an alternative meet

Federal, State and Tribal

environmental statutes,

regulations, and other

requirements relevant to

the site, or is a waiver

justified?

Complies with, or

waives ARARsComplies with ARARs

Long Term

Effectiveness and

Performance

Does an alternative

maintain protection of

human health and the

environment over time?

Moderately to highly

effectiveHighly effective

Reduction of toxicity,

Does an alternative use

treatment to reduce a

contaminants harmful

Alternative1

Thre

sho

ldC

rite

ria

Reduction of toxicity,

mobility, or volume

through treatment

contaminants harmful

effects or ability to move in

the environment and the

amount of contamination

remaining after cleanup?

No No

Short-Term

Effectiveness

How much time is needed

to implement an alternative

and the risk the alternative

poses to workers, residents

and the environment during

implementation?

Highly effective Highly effective

Implementability

What is the technical and

administrative feasibility of

implementing the

alternative, including factors

such as availability of

materials and services?

Readily implementable Readily implementable

Bal

anci

ng

Cri

teri

a


June 30, 2017

Table 6.2

Summary of Remedial Alternative Evaluation Criteria

Criterion Description

1

No Action

2

(Soil Removal to 12")

3

(Soil removal to 18")

Alternative1

Cost

What are the estimated

capital and annual

operations and maintenance

costs, as well as present

value cost?

Capital Cost:

$41,196,000

Present Value:

$34,371,000

Capital Cost:

$43,829,000

Present Value:

$36,463,000

State / Support

agency acceptance

Does the State agree with

EPA's analyses and

recommendations?To Be Determined2 To Be Determined2

Community

Acceptance

Doest the community agree

with EPA's analyses and

preferred alternative?To Be Determined2 To Be Determined2

1 - Indoor dust cleanups are included as components of Alternatives 2 and 3.

2 - State and Community Acceptance will be evaluated after receipt of comments on

the Proposed Plan.

Mo

dif

yin

gC

rite

ria

Notes:


June 30, 2017