United States

Environmental Protection

Agency EPA

1200 PennsylvaniaAvenue, N.W.

Washington, DC 20460 December 2013

O ce of Solid Waste and Emergency Response

Support Document for the 

Revised National Priorities List 

Final Rule – 

Jackpile-Paguate Uranium Mine 
Support Document for the

Revised National Priorities List

Final Rule

Jackpile-Paguate Uranium Mine

December 2013 

Site Assessment and Remedy Decisions Branch

Office of Superfund Remediation and Technology Innovation 

Office of Solid Waste and Emergency Response 

U.S. Environmental Protection Agency 

Washington, DC 20460
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

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Table of Contents

Executive Summary................................................................................................................................................ iii

Introduction ............................................................................................................................................................ iv

Background of the NPL ....................................................................................................................................... iv

Development of the NPL ..................................................................................................................................... iv

Hazard Ranking System .........................................................................................................................................v

Other Mechanisms for Listing ............................................................................................................................. vi

Organization of this Document ............................................................................................................................ vi

Glossary .............................................................................................................................................................. vii

1. List of Commenters and Correspondence .....................................................................................................1

2. Site Description ................................................................................................................................................1

3. Summary of Comments ...................................................................................................................................7

3.1 Support for Listing and Other Non-opposition Comments ......................................................................10

3.2 Accuracy of Site Summary .......................................................................................................................10

3.2.1 December 1986 Agreements............................................................................................................................11

3.2.2 Deviation from ROD Requirements................................................................................................................12

3.2.3 Site Conditions Following Reclamation..........................................................................................................12

3.3 Consideration of Manganese Secondary Drinking Water Criteria ...........................................................13

3.4 Danger to Human Health and the Environment .......................................................................................14

3.5 Evaluation of Other Pathways ..................................................................................................................16

3.6 Data Sufficiency for Listing on the NPL ..................................................................................................17

3.7 Liability ....................................................................................................................................................19

3.8 Future Remediation Effectiveness/Purpose for Listing ............................................................................20

3.9 Consideration of Response Actions/Current Conditions ..........................................................................21

3.10 Surface Water Pathway Description: Source 1 .........................................................................................24

3.11 Sources 1 and 2 Characterization: Association of Hazardous Substances ...............................................26
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3.12 Waste Quantity .........................................................................................................................................29

3.13 Other Possible Sources: Association of Hazardous Substances ...............................................................31

3.14 Surface Water Pathway Description: In-Water Segment .........................................................................33

3.15 Likelihood of Release: Background and Significant Increase ..................................................................35

3.16 Likelihood of Release: Attribution ...........................................................................................................42

3.16.1 Background Samples Screening of Natural Levels .........................................................................................46

3.16.2 Collection of Storm Runoff Background Samples ..........................................................................................48

3.16.3 Ground Water Background Samples for Overland/Flood Component............................................................49

3.16.4 Consideration of Naturally Occurring Releases ..............................................................................................53

3.16.5 Effects of Evaporation.....................................................................................................................................59

3.16.6 Effects of Wind Deposition .............................................................................................................................60

3.16.7 Attribution to a Source ....................................................................................................................................60

3.16.8 Storm Water Runoff Data................................................................................................................................61

3.17 Site Watershed/Target Distance Limit .....................................................................................................63

3.18 Human Food Chain Threat: Evidence of Fishing for Consumption .........................................................65

3.19 Human Food Chain Threat: Use of Bioaccumulation Value ....................................................................69

3.20 Human Food Chain Threat: Toxicity/Persistence/Bioaccumulation ........................................................73

3.21 Ground Water to Surface Water Migration Component: Background .....................................................74

3.22 Ground Water to Surface Water Migration Component: Presence of Water in Pits ................................78

3.23 Ground Water: Flow Direction/Targets ....................................................................................................80

3.24 Accuracy of the EPA Site Narrative .........................................................................................................82

3.24.1 Magnitude of Contamination...........................................................................................................................82

3.24.2 Post-Reclamation Releases..............................................................................................................................84

3.24.3 Potential Impacts.............................................................................................................................................85

3.24.4 List of Contaminants .......................................................................................................................................86

3.25 Waste Characteristics ...............................................................................................................................87

3.25.1 Drinking Water Threat Waste Characteristics................................................................................................. 87

3.25.2 Human Food Chain Threat Waste Characteristics...........................................................................................91

4. Conclusion ......................................................................................................................................................93
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Executive Summary 

Section 105(a)(8)(B) of CERCLA, as amended by SARA, requires that the EPA prepare a list of national 

priorities among the known releases or threatened releases of hazardous substances, pollutants, or contaminants 

throughout the United States. An original National Priorities List (NPL) was promulgated on September 8, 1983 

(48 FR 40658). CERCLA requires that EPA update the list at least annually. 

This document provides responses to public comments received on the Jackpile-Paguate Uranium Mine site, 

proposed on March 15, 2012 (77 FR 15344). This site is being added to the NPL based on an evaluation under 

EPA’s Hazard Ranking System (HRS) in a final rule published in the Federal Register in December 2013. 
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Introduction

This document explains the rationale for adding the Jackpile-Paguate Uranium Mine site (the Site) in Paguate, 

New Mexico to the National Priorities List (NPL) of uncontrolled hazardous waste sites and provides responses to 

public comments received on this site listing proposal. The EPA proposed this site to the NPL on March 15, 2012

(77 FR 15344). This site is being added to the NPL based on an evaluation under the Hazard Ranking System 

(HRS) in a final rule published in the Federal Register in December 2013. 

Background of the NPL 

In 1980, Congress enacted the Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA), 42 U.S.C. Sections 9601 et seq. in response to the dangers of uncontrolled hazardous waste sites. 

CERCLA was amended on October 17, 1986, by the Superfund Amendments and Reauthorization Act (SARA), 

Public Law No. 99-499, stat., 1613 et seq. To implement CERCLA, EPA promulgated the revised National Oil 

and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part 300, on July 16, 1982 (47 FR 31180), 

pursuant to CERCLA Section 105 and Executive Order 12316 (46 FR 42237, August 20, 1981). The NCP, further 

revised by EPA on September 16, 1985 (50 FR 37624) and November 20, 1985 (50 FR 47912), sets forth 

guidelines and procedures needed to respond under CERCLA to releases and threatened releases of hazardous 

substances, pollutants, or contaminants. On March 8, 1990 (55 FR 8666), EPA further revised the NCP in 

response to SARA.

Section 105(a)(8)(A) of CERCLA, as amended by SARA, requires that the NCP include 

criteria for determining priorities among releases or threatened releases throughout the United 

States for the purpose of taking remedial action and, to the extent practicable, take into account 

the potential urgency of such action, for the purpose of taking removal action. 

Removal action involves cleanup or other actions that are taken in response to emergency conditions or on a 

short-term or temporary basis (CERCLA Section 101). Remedial action is generally long-term in nature and 

involves response actions that are consistent with a permanent remedy for a release (CERCLA Section 101). 

Criteria for placing sites on the NPL, which makes them eligible for remedial actions financed by the Trust Fund 

established under CERCLA, were included in the HRS. EPA promulgated the HRS as Appendix A of the NCP 

(47 FR 31219, July 16, 1982). On December 14, 1990 (56 FR 51532), EPA promulgated revisions to the HRS in 

response to SARA, and established the effective date for the HRS revisions as March 15, 1991.

Section 105(a)(8)(B) of CERCLA, as amended, requires that the statutory criteria provided by the HRS be used to 

prepare a list of national priorities among the known releases or threatened releases of hazardous substances, 

pollutants, or contaminants throughout the United States. The list, which is Appendix B of the NCP, is the NPL. 

An original NPL of 406 sites was promulgated on September 8, 1983 (48 FR 40658). At that time, an HRS score 

of 28.5 was established as the cutoff for listing because it yielded an initial NPL of at least 400 sites, as suggested 

by CERCLA. The NPL has been expanded several times since then, most recently on May 24, 2013 (78 FR 

31417). The Agency also has published a number of proposed rulemakings to add sites to the NPL. The most 

recent proposal was on May 24, 2013 (78 FR 31464). 

Development of the NPL 

The primary purpose of the NPL is stated in the legislative history of CERCLA (Report of the Committee on 

Environment and Public Works, Senate Report No. 96-848, 96th Cong., 2d Sess. 60 [1980]). 
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The priority list serves primarily informational purposes, identifying for the States and the public 

those facilities and sites or other releases which appear to warrant remedial actions. Inclusion of a 

facility or site on the list does not in itself reflect a judgment of the activities of its owner or 

operator, it does not require those persons to undertake any action, nor does it assign liability to 

any person. Subsequent government actions will be necessary in order to do so, and these actions 

will be attended by all appropriate procedural safeguards. 

The NPL, therefore, is primarily an informational and management tool. The identification of a site for the NPL is 

intended primarily to guide EPA in determining which sites warrant further investigation to assess the nature and 

extent of the human health and environmental risks associated with the site and to determine what CERCLAfinanced remedial action(s), if any, may be appropriate. The NPL also serves to notify the public of sites EPA 

believes warrant further investigation. Finally, listing a site may, to the extent potentially responsible parties are 

identifiable at the time of listing, serve as notice to such parties that the Agency may initiate CERCLA-financed 

remedial action.

CERCLA Section 105(a)(8)(B) directs EPA to list priority sites among the known releases or threatened release 

of hazardous substances, pollutants, or contaminants, and Section 105(a)(8)(A) directs EPA to consider certain 

enumerated and other appropriate factors in doing so. Thus, as a matter of policy, EPA has the discretion not to 

use CERCLA to respond to certain types of releases. Where other authorities exist, placing sites on the NPL for 

possible remedial action under CERCLA may not be appropriate. Therefore, EPA has chosen not to place certain 

types of sites on the NPL even though CERCLA does not exclude such action. If, however, the Agency later 

determines that sites not listed as a matter of policy are not being properly responded to, the Agency may consider 

placing them on the NPL. 

Hazard Ranking System

The HRS is the principal mechanism EPA uses to place uncontrolled waste sites on the NPL. It is a numerically 

based screening system that uses information from initial, limited investigations – the preliminary assessment and 

site inspection – to assess the relative potential of sites to pose a threat to human health or the environment. HRS 

scores, however, do not determine the sequence in which EPA funds remedial response actions, because the 

information collected to develop HRS scores is not sufficient in itself to determine either the extent of 

contamination or the appropriate response for a particular site. Moreover, the sites with the highest scores do not 

necessarily come to the Agency's attention first, so that addressing sites strictly on the basis of ranking would in 

some cases require stopping work at sites where it was already underway. Thus, EPA relies on further, more 

detailed studies in the remedial investigation/feasibility study that typically follows listing.

The HRS uses a structured value analysis approach to scoring sites. This approach assigns numerical values to 

factors that relate to or indicate risk, based on conditions at the site. The factors are grouped into three categories. 

Each category has a maximum value. The categories are:

• likelihood that a site has released or has the potential to release hazardous substances into the 

environment; 

• characteristics of the waste (e.g., toxicity and waste quantity); and

• targets (e.g., people or sensitive environments) affected by the release.

Under the HRS, four pathways can be scored for one or more components and threats as identified below:

• Ground Water Migration (Sgw) 
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• Surface Water Migration (Ssw) 

The following threats are evaluated for two separate migration components, overland/flood migration and 

ground water to surface water.

- drinking water 

- human food chain 

- sensitive environments

• Soil Exposure (Ss) 

- resident population

- nearby population 

• Air Migration (Sa) 

- population 

After scores are calculated for one or more pathways according to prescribed guidelines, they are combined using 

the following root-mean-square equation to determine the overall site score (S), which ranges from 0 to 100: 

4

S + S + S + S = S

2

a

2

s

2

sw

2

gw

If all pathway scores are low, the HRS score is low. However, the HRS score can be relatively high even if only 

one pathway score is high. This is an important requirement for HRS scoring because some extremely dangerous 

sites pose threats through only one pathway. For example, buried leaking drums of hazardous substances can 

contaminate drinking water wells, but – if the drums are buried deep enough and the substances not very volatile 

– not surface water or air.

Other Mechanisms for Listing 

There are two mechanisms other than the HRS by which sites can be placed on the NPL. The first of these 

mechanisms, authorized by the NCP at 40 CFR 300.425(c)(2), allows each State and Territory to designate one 

site as its highest priority regardless of score. The last mechanism, authorized by the NCP at 40 CFR 

300.425(c)(3), allows listing a site if it meets the following three requirements: 

• Agency for Toxic Substances and Disease Registry (ATSDR) of the U.S. Public Health Service has 

issued a health advisory that recommends dissociation of individuals from the release; 

• EPA determines the site poses a significant threat to public health; and 

• EPA anticipates it will be more cost-effective to use its remedial authority than to use its emergency 

removal authority to respond to the site. 

Organization of this Document 

The following section contains EPA responses to site-specific public comments received on the proposal of the 

Jackpile-Paguate Uranium Mine site on March 15, 2012 (77 FR 15344). The site discussion begins with a list of 

commenters, followed by a site description, a summary of comments, and Agency responses to each comment. A 

concluding statement indicates the effect of the comments on the HRS score for the Site.
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Glossary 

The following acronyms and abbreviations are used throughout the text: 

Agency U.S. Environmental Protection Agency 

AMC Anaconda Minerals Company

ARC Atlantic Richfield Company 

ATSDR Agency for Toxic Substances and Disease Registry

BIA Bureau of Indian Affairs 

BLM Bureau of Land Management 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of 1980, 42 

U.S.C. Sections 9601 et seq., also known as Superfund 

CFR Code of Federal Regulations 

CFS Cubic feet per second 

EIS Environmental Impact Statement

EPA U.S. Environmental Protection Agency 

ESI Expanded Site Inspection 

FR Federal Register

GPM Gallons per minute 

HRS Hazard Ranking System, Appendix A of the NCP 

HRS score Overall site score calculated using the Hazard Ranking System; ranges from 0 to 100

MCL Maximum Contaminant Level 

mg/l Milligram per liter

NCP National Oil and Hazardous Substances Pollution Contingency Plan, 40 C.F.R. Part 300 

NPL National Priorities List, Appendix B of the NCP

ORP Oxidation-reduction potential 

pCi/m3 picoCuries per cubic meter

pCi/l picoCuries per liter 

pCi/kg picoCuries per kilogram

PPE Probable point of entry

QASP Quality Assurance Sampling Plan

RI Remedial Investigation

RI/FS Remedial Investigation/Feasibility Study

ROD Record of Decision

SARA Superfund Amendments and Reauthorization Act 

SCDM Superfund Chemical Data Matrix 
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SI Site Inspection

SQL Sample Quantitation Limit

TDS Total Dissolved Solids

TDL Target Distance Limit
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1. List of Commenters and Correspondence

EPA-HQ-SFUND-2012-0069-0006 Correspondence, dated November 22, 2011, from Richard B. 

Luarkie, Governor, Pueblo of Laguna. 

EPA-HQ-SFUND-2012-0069-0006 Comment, dated March 27, 2012, submitted by Thomas A. 

Parkhill.

EPA-HQ-SFUND-2012-0069-0007 Comment, dated May 14, 2012, submitted by June L. and Lucy 

P. Lorenzo. 

EPA-HQ-SFUND-2012-0069-0008 Comment, dated May 14, 2012, submitted by Manuel F. Pino.

EPA-HQ-SFUND-2012-0069-0009 Comment, dated May 14, 2012, submitted by William J. Duffy, 

Counsel, Davis Graham & Stubbs LLP (DGS) on behalf of 

Atlantic Richfield Company (ARC). 

Comment attachment, submitted May 14, 2012. Atlantic 

Richfield Company’s Comments on the Hazard Ranking System 

Documentation Record for the Jackpile-Paguate Uranium Mine.

2. Site Description

The Jackpile-Paguate Uranium Mine site (the Site) presented in the HRS documentation record at proposal 

includes two pile sources contaminated with metals and radionuclides, and releases of metals and radionuclides to 

the Rio Moquino, Rio Paguate, and the Paguate Reservoir. 

Site History

The Site is located on the Laguna Indian Reservation about 40 miles west of Albuquerque in Paguate, Cibola 

County, New Mexico. The mine property is located in an area of canyons and arroyos to the east of the village of 

Paguate. The former uranium mine facility encompasses approximately 7,868 acres and includes the two pile 

sources. The Rio Moquino and Rio Paguate run through the mine and converge near the mine center; below this 

confluence, the Rio Paguate flows southeasterly into Paguate Reservoir before joining the Rio San Jose 5 miles 

south of the mine facility. (See Figure 1 of this support document for a general illustration of site layout.) 

Overburden and ore-associated waste were stockpiled within the mine area, stockpiled in an adjacent river’s (Rio 

Moquino) floodplain, or placed in the mined-out areas of the pits as backfill. For the purpose of the HRS 

documentation record at proposal, the approximate “boundaries” of the facility include approximately 2,656 acres 

which were disturbed and contained three open pits that were between 200 and 300 feet deep, 32 waste dumps, 

and 23 protore1 stockpiles. The mine was operated by Anaconda Minerals Company (AMC), a division of 

Atlantic Richfield Company. Mining operations were conducted from 1953 through early 1982, and ceased

because of depressed uranium mining conditions. During the 29 years of mining, approximately 400 million tons 

of rocks were moved within the mine area and approximately 25 million tons of uranium ore were transported via 

the Santa Fe Railroad from the mine to Anaconda’s Bluewater Mill, approximately 40 miles west of the property. 

The town of Paguate is located adjacent to and west of the property with a population of approximately 492 

persons, according to the 2000 census. The remaining surrounding area is mainly undeveloped, with a varied 

 

1 As described on page 27 of the HRS documentation record at proposal, “protore” is material that was stockpiled throughout 

the mining operation because it contained elevated but sub-economic uranium concentrations.
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topography that contains wildlife consisting of elk, antelope, goats, and mule deer. There is also a population of 

approximately 1,500 domesticated cattle on the Laguna Reservation. According to Laguna officials, contaminated 

source material is present along the river bank and would be in direct contact with surface water when the river is 

flowing. There is documentation of fishing occurring within these perennial rivers and that the fish are used for 

human consumption. 

Site Reclamation Activities

In December 1986, under a series of agreements between the Bureau of Indian Affairs (BIA) and the Pueblo of 

Laguna, it was agreed that the Pueblo of Laguna would perform the management, coordination, and 

administration of the Jackpile-Paguate Reclamation Project in accordance with the requirements set forth in the 

Jackpile-Paguate Environmental Impact Statement (EIS) and the associated Record of Decision (ROD).

Reclamation of the Jackpile-Paguate Uranium Mine commenced in 1990. The “preferred alternative” reclamation 

plan incorporated the following: backfilling of the open pit areas to at least 10 feet above projected ground water 

recovery levels using protore and waste rock dump material; slope reduction of the upper 15 feet of highwall 

slopes; recontouring and covering of remaining waste rock dumps; completion of arroyo drainage improvements 

and erosion controls; decontamination of those structures to remain, and removal/disposal of all non-essential 

structures; plugging and bulkheading of underground ventilation raises and decline portals, respectively; 

reclamation of miscellaneous features such as wells, access roads, rail spurs, drill holes, etc.; property-wide 

revegetation of disturbed areas; and provision of property security and long-term monitoring of reclamation 

success for a period of not less than 10 years. On June 10, 1995, the Laguna Construction Company, which was in 

charge of the reclamation, officially closed out the Jackpile Reclamation Project. Post-reclamation land uses for 

the property include limited livestock grazing, light manufacturing, office space, mining, and major equipment 

storage. Habitation and farming are excluded. 

Post Reclamation Evaluations 

In September 2007, a ROD Compliance Assessment for the Jackpile-Paguate Uranium Mine was completed by 

OA Systems Corporation to determine if the reclamation activities had met the requirements of the ROD. This 

report concluded that reclamation of the mine was still not complete as several non-compliant and potentially 

non-compliant issues still needed to be addressed.

As part of the ROD Compliance Assessment, surface water data were evaluated for 10 years between 1996 and 

2006. And as part of the Water Pollution Program Grants (Section 106) program, the Pueblo of Laguna 

Environmental and Natural Resources Department has been collecting surface water samples along the surface 

water pathway quarterly from 2005 through 2009. During these evaluations, several samples exhibited uranium 

and manganese contamination in the Rio Moquino, Rio Paguate, Paguate Reservoir, and Rio San Jose. These 

results indicated contamination within the surface water pathway. According to the ROD Compliance 

Assessment, several data gaps remained and it was recommended that further monitoring and evaluation be 

performed. 

To further characterize the Site, the EPA conducted a site inspection (SI) and an expanded site investigation (ESI) 

in March 2010 and April 2011, respectively. 

HRS Evaluation 

The HRS documentation record at proposal identifies two sources at the Site. Source 1 consists of waste material, 

protore, and overburden associated with three mining pits (the North Paguate Pit, the South Paguate Pit, and the 

Jackpile Pit). These materials were used to backfill the pits during the later years of mining and during 

reclamation activities following the cessation of mining activities. The EPA SI and ESI sampling identified the 
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presence of various hazardous substances associated with this mining waste, including uranium, thorium, and 

radium radionuclide isotopes (uranium-234, uranium-235, uranium-238, thorium-228, thorium-230, radium-226, 

and radium-228), and metals (chromium, cobalt, manganese, vanadium, and zinc). The three pits were aggregated 

into one source for HRS purposes in the HRS documentation record at proposal because of shared source type 

(piles), hazardous substances, HRS targets, HRS containment values, and watershed. Source 2 is a waste dump 

(identified as Waste Dump V) containing contaminated waste rock. A sample of this source collected during the 

EPA SI identified the presence of uranium isotopes (uranium-234, uranium-235, and uranium-238), manganese, 

and vanadium. Both sources were found to be uncontained to surface water for HRS purposes. (See Figure 1 of 

this support document for approximate pit and waste dump locations.) 

Surface water samples collected during the EPA SI and EPA ESI establish observed releases of uranium isotopes 

and manganese at several points in the Rio Moquino, Rio Paguate, and Paguate Reservoir. (See Figures 2 and 3 of 

this support document for EPA SI and EPA ESI sample locations, respectively.) 

For the overland/flood migration component of the surface water migration pathway, targets include a human 

food chain fishery present within the Rio Paguate, and Rio Paguate resources (i.e., the use of the water for 

irrigation, watering of livestock, and recreation). 

Additionally, although not scored, the HRS documentation record at proposal presents information showing that 

the ground water to surface water migration component of the surface water migration pathway is also of concern. 

Hydrologic observations and modeling indicate that pit waters (i.e., from Source 1) present on the property are not 

contained and flow into the surface water system via ground water pathways, carrying contaminants into that 

system. Chemical data also suggest that chemical reactions in the backfilled pits, and subsequent migration of 

contaminants to ground water, may be shifting the chemistry of surface water at, and downgradient of the 

property. 
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3. Summary of Comments

Three commenters submitted comments in support of placing the Site on the NPL. Among the reasons for 

this support were concern over the effectiveness of past reclamation activities and remaining risk posed 

by the Site, concern that all potential pathways by which contamination may migrate be addressed, and 

the desire for further investigation and remediation to take place. 

Comments were submitted in opposition to NPL listing by the Atlantic Richfield Company (hereafter 

referred to as ARC, the name the commenter used) and Mr. Thomas A. Parkhill. ARC stated that “the 

HRS Documentation Record does not conform with the HRS, or the requirements of the National 

Contingency Plan. Thus, should EPA proceed to finalize the present listing proposal, EPA’s decision to 

list the Jackpile Mine would be arbitrary and capricious, and otherwise not in accordance with law.” Mr. 

Parkhill asserted that the Site should not be a Superfund site, and cited aspects of local geology in the area 

as evidence opposing the HRS evaluation. 

ARC found fault in the Site Summary section of the HRS documentation record at proposal, asserting the 

following: 

• The Site Summary should have mentioned the December 2, 1986 agreement between the Pueblo 

of Laguna and AMC. 

• The Site Summary did not document deviation in the reclamation project from project 

requirements. 

• The Site Summary text did not accurately describe the post-reclamation condition of disturbed 

acreage, pits, waste dumps, and protore stockpiles. 

• The Site Summary text inappropriately included a comparison of surface water manganese 

concentrations to National Secondary Drinking Water Standards, as the National Secondary 

Maximum Contaminant Level (MCL) for manganese; and the human health/environmental 

concern posed by manganese is questionable. 

ARC further made several comments questioning whether the available information used in the HRS 

documentation record at proposal is sufficient for the purposes of listing a site on the NPL, including the 

following assertions: 

• Insufficient sampling was conducted to characterize background areas, source areas, surface 

waters, and other possible sources; further, there is little support for these samples, and they are 

not representative of actual site conditions. 

• Further assessment of whether runoff can migrate from Source 1 pits is needed to establish 

probable points of entry (PPEs) and whether the pits contributed to surface water contamination. 

• Further assessment of stream systems, ground water, and surface water is needed to support the 

EPA’s description of the surface water pathway and the rivers included as perennial. 

• Storm water runoff samples should have been collected to quantify source contribution of 

hazardous substances to the surface water. 

• Wind deposition should have been investigated to adequately support attribution of contamination 

to the Site. 

• Because an HRS documentation record reference stated that contribution of hazardous substances 

from natural sources at the Site could not be ruled out, it is clear the EPA has insufficient 

information for NPL designation of the Site. 
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• The EPA must present and take into account evidence of metals concentrations prior to mining 

activities in order to attribute the observed release to mining operations. 

• The EPA should have collected tissue samples to support bioaccumulation factors used. 

ARC submitted comments related to the liability for cleanup of contamination at the Site, noting that 

under previous agreements the Pueblo of Laguna was to conduct reclamation of the Site with government 

oversight, and that ARC had contributed substantial funding for reclamation activities. On this subject, 

Mr. Parkhill commented had the “Best Available Technology” been used in reclamation, the migration of 

uranium and other metals to ground or surface water would have been prevented; Mr. Parkhill asserted 

that the Pueblo of Laguna should be held responsible for any deficiencies. Mr. Parkhill also questioned 

whether there is a benefit in further remediation, claiming that because there is naturally occurring 

uranium throughout the area, no site remedies will completely eliminate the issue of uranium 

contamination.

ARC and Mr. Parkhill took issue with several aspects of the HRS evaluation related to Source 1. On the 

area of Source 1 pits scored, ARC claimed that it is inappropriate to include portions of the pits as part of 

Source 1 if runoff from those areas would not enter surface water, arguing that a drainage study should 

have been performed to evaluate this. ARC challenged the eligibility of Source 1 for the surface water 

pathway, the overland segment of hazardous substance migration from Source 1, and the probable points 

of entry of hazardous substances from Source 1 to surface water; these challenges were based on the 

assertion that runoff could not carry hazardous substances from the Source 1 pits to surface water, as the 

pits are closed basins, covered with top soil, and partially re-vegetated. Mr. Parkhill noted that in a 

previous visit to the Site, he observed the Source 1 pits to be dry; on this basis he claimed that the pits are 

above the water table and could not contribute metals to the ground water or surface water. ARC also 

asserted that it was inappropriate to rely on radium data presented (used in characterizing Source 1), 

contending that the level of validation carried out for the related analytical results was inadequate. 

ARC claimed that “background surface water sampling failed to satisfy the HRS criteria because the 

sampling design failed to support collection of data that reflect actual site conditions,” and that 

“[a]dditional background surface water sampling is necessary to properly score the Jackpile site.” ARC 

asserted that this deficiency impacts the likelihood of release factor value of 550 assigned in the HRS 

documentation record at proposal. ARC supported this claim with several arguments: 

• The number and location of surface water background samples was not adequate to determine 

background levels for the Site and not representative of Site conditions. 

• The background samples do not adequately address the metals contributed to surface water by 

naturally occurring rock formations in the area. 

• Background samples should have been collected during rain events to address contaminants 

contributed by runoff. 

• Surface water background samples did not adequately account for contaminant contributions 

from ground water. 

• The possibility of wind-transported hazardous substances has not been accounted for. 

ARC and Mr. Parkhill challenged the attribution of the significant increase in hazardous substances found 

in surface water observed releases to the Site. These challenges were based on several assertions:
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• ARC and Mr. Parkhill claimed metals found in surface water are more likely due to natural rock 

formations in the area rather than the sources at the Site. 

• ARC contended that proper background levels have not been established for uranium-bearing 

ground water discharging from the underlying Jackpile sandstone and mixing with the surface 

water. 

• ARC reasoned that the HRS documentation record should have documented uranium and 

manganese levels before mining operations began to show that observed releases are due to 

mining and not natural sources. 

• Mr. Parkhill noted that in prior decades there was no water in the pits, indicating that the mine is 

above the water table and could not have contaminated ground water or surface water. 

• Mr. Parkhill posited that elevated metals concentrations in surface water may be due to high 

evaporation rates in the area. 

• ARC generally challenged whether the observed release was effectively attributed to sources at 

the Site. 

• ARC claimed that storm water runoff data should have been collected to adequately determine the 

contaminants contributed from any sources. 

Mr. Parkhill claimed that the mine is too far from Rio San Jose to have any effect on that water body. 

ARC challenged several aspects of the human food chain threat evaluation. ARC asserted that EPA’s 

documentation of fishing is inadequate. ARC similarly felt that evidence of traditional/cultural use of the 

rivers was lacking. ARC claimed that the use of bioaccumulation values is inappropriate without fish 

tissue data to support the values. Finally, ARC noted that there are errors in the calculations of 

toxicity/persistence/bioaccumulation values presented in the HRS documentation record at proposal. 

On the information presented for the non-scored ground water to surface water migration component in 

the HRS documentation record at proposal, ARC took issue with the background ground water samples 

shown. ARC asserted that an examination of uranium-234/uranium-238 ratios indicates that the source of 

the uranium in these background samples is different than that for the ground water release samples below 

the mine; therefore, ARC reasoned that the background samples are not representative of actual 

background conditions for the mine and are inappropriate for use. On the subject of the same ground 

water to surface water migration component, Mr. Parkhill claimed that any contaminants in ground water 

would flow north-northwest, away from the Pueblo of Laguna. 

ARC submitted comments related to the EPA NPL Site Narrative document, stating that it “contains 

statements that ARC believes are misleading, unsupported by the record and/or incorrect.” ARC claimed 

that the EPA NPL Site Narrative statements regarding high levels of uranium in surface water 

downstream of the mine and post-reclamation releases are inaccurate, based on ARC’s assertions 

questioning the establishment of an observed release at the Site. ARC found an EPA NPL Site Narrative 

statement discussing Site impacts on fishing and traditional/cultural use of surface water to be inaccurate 

based on those same challenges to the observed release establishment, and challenges to documentation of 

these surface water uses. Finally, ARC disputed the EPA NPL Site Narrative list of contaminants 

associated with the Site.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

10 

3.1 Support for Listing and Other Non-opposition Comments 

Comment: Richard B. Luarkie, Governor of the Pueblo of Laguna expressed support for placement of the 

Site on the NPL, stating 

Reclaiming a mine of this size proven to be no easy task and the Pueblo of Laguna is still 

coping with many side effects of mining. The legacy issues include, but are not limited 

to, elevated to highly elevated levels of isotopic uranium in surface water below the mine 

area in Rio Paguate and Rio San Jose. The water is our most valuable natural resource, 

and surface water is a primary source for irrigation, livestock and wildlife on the 

reservation. There is also a very important factor, with direct impact to human health, of 

protecting the traditional and cultural uses of surface water. 

Additionally, three commenters (June L. Lorenzo, Lucy P. Lorenzo, and Manuel F. Pino) submitted 

comments in support of placing the Site on the NPL. The reasons for this support included: 

• The need for further investigation/remediation at the Site. 

• Concern regarding the effectiveness of past remediation. 

• Concern for health effects posed by the Site. 

• Concern over site impacts on cultural, agricultural, and economic use of the Rio Paguate and Rio 

Moquino. 

• Involvement of the public in future remedies for the Site. 

• A request that the Site be dealt with before any other new mines or mills are allowed to operate in 

the Grants Mineral Belt. 

Response: The Jackpile-Paguate Uranium Mine site has been added to the NPL. Listing makes a site 

eligible for remedial action funding under CERCLA. The Jackpile-Paguate Uranium Mine site will be 

further investigated during the remedial investigation/feasibility study (RI/FS) phase of the Superfund 

process to determine what response, if any, is appropriate. Actual funding may not necessarily be 

undertaken in the precise order of HRS scores, however, and upon more detailed investigation may not be 

necessary at all in some cases. EPA determines the need for using Superfund monies for remedial 

activities on a site-by-site basis, taking into account the NPL ranking, State priorities, further site 

investigation, other response alternatives, and other factors as appropriate. 

3.2 Accuracy of Site Summary 

Comment: ARC made multiple comments on aspects of the Site Summary section of the HRS 

documentation record at proposal, including the following: 

• The Site Summary should have mentioned the December 2, 1986 agreement between the Pueblo 

of Laguna and AMC. 

• The Site Summary did not document deviation in the reclamation project from project 

requirements. 

• The Site Summary text did not accurately describe the post-reclamation condition of disturbed 

acreage, pits, waste dumps, and protore stockpiles. 

• The Site Summary text on page 7 of the HRS documentation record inappropriately included a 

comparison of surface water manganese concentrations to National Secondary Drinking Water 

Standards, and the human health/environmental concern posed by manganese is questionable. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

11 

Response: The site summary as written meets its purpose. The Site Summary section of the HRS 

documentation record at proposal is meant to present sufficient information for the public to understand 

the history and conditions of the site sufficient to introduce the HRS scoring approach for the site; the Site 

Summary itself is not used to directly determine any HRS factor values used to calculate the HRS site 

score. As presented below, the revisions suggested by ARC result in no revision to the HRS evaluation or 

the NPL listing decision. However, as the comments, this support document, and the discussion of the 

proposed additions are part of the public record for the Site, the information in ARC’s comments have 

also been added to the public record for the Site.

Regarding the comparison of manganese concentrations to secondary drinking water criteria, as explained 

in section 3.3, Consideration of Manganese Secondary Drinking Water Criteria, of this support document, 

the comparison of manganese concentrations in surface water samples to the EPA’s National Secondary 

Drinking Water standards is presented as background information for the public and was not used for 

HRS scoring purposes. And, as explained in section 3.4, Danger to Human Health and Environment, of 

this support document, manganese qualifies as a hazardous substance under the HRS; therefore, the 

analytical data used to establish an observed release by chemical analysis for manganese are eligible for 

consideration due to the relative risk it poses to human health and the environment. 

Furthermore, the Site Summary section and other sections of HRS documentation record at proposal did 

address the commenter’s specific points as explained in the following subsections:

• 3.2.1 December 1986 Agreements

• 3.2.2 Deviation from ROD Requirements 

• 3.2.3 Site Conditions Following Reclamation

3.2.1 December 1986 Agreements

Comment: ARC asserted that the Site Summary was incomplete, as it did not mention the December 2, 

1986 agreement between the Pueblo of Laguna and AMC “to terminate all then-existing mine site leases 

for the Jackpile Mine.” Under this agreement, approved by the United States Department of the Interior, 

the Pueblo of Laguna “agreed to perform the final reclamation of the mine site under federal government 

oversight.” This reclamation project was called the Jackpile-Paguate Reclamation Project. ARC also 

noted that AMC provided the Pueblo of Laguna with funds “that substantially exceeded the Bureau of 

Land Management reclamation estimate for this purpose.” 

Response: The HRS documentation record did note a series of agreements in December 1986 between the 

Bureau of Indian Affairs and the Pueblo of Laguna – this is mentioned in the Site Summary section on 

page 6 of the HRS documentation record at proposal:

In December 1986, under a series of agreements between the Bureau of Indian Affairs 

(BIA) and the Pueblo of Laguna, it was agreed that the Pueblo of Laguna would perform 

the management, coordination, and administration of the Jackpile-Paguate Reclamation 

Project in accordance with the requirements set forth in the Jackpile-Paguate 

Environmental Impact Statement (EIS) and the associated Record of Decision (ROD) 

(Ref. 5, p. 184). 

In any case, the terms of the agreements are not relevant to the HRS score. Also, to the extent this 

comment involves liability at the Site, as explained in section 3.7, Liability, of this support document, 

liability for a potentially responsible party is not considered in an HRS evaluation. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

12 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL. 

3.2.2 Deviation from ROD Requirements

Comment: ARC asserted that the Site Summary did not provide an analysis or description of any 

deviation in the reclamation project (conducted by the Pueblo of Laguna with involvement of the federal 

government) from “DOI–approved reclamation requirements.” 

Response: The HRS documentation record at proposal did mention that there were deviations from the 

ROD requirements for reclamation. Page 7 of the HRS documentation record at proposal, Site Summary 

section, notes that

[i]n September 2007, a ROD Compliance Assessment for Jackpile-Paguate Uranium 

Mine was completed by OA Systems Corporation to determine if the post-reclamation 

had met the requirements of the ROD. This report concluded that reclamation of the mine 

was still not complete as several non-compliant and potentially non-compliant issues still 

needed to be addressed (Ref. 5, pp. 80 to 92). 

As further detailed in section 3.9, Consideration of Response Actions/Current Conditions, of this support 

document, Reference 5 cited in the quoted text above is the September 2007 ROD Compliance 

Assessment; pages 80 to 92 of that document summarize the conclusions and recommendations of the 

assessment related to issues found to be not compliant with the 1986 ROD. In any case, the deviations 

from the ROD are not relevant to the HRS score.

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.2.3 Site Conditions Following Reclamation

Comment: ARC commented that the Site Summary text on page 6 of the HRS documentation record at 

proposal describing disturbed acreage, pits, waste dumps, and protore stockpiles accurately described Site 

conditions before the reclamation work, but not afterwards. ARC stated that the site description would 

need to be corrected to depict current site conditions following reclamation activities implemented by the 

Pueblo of Laguna, with the approval of federal agencies. 

Response: The HRS documentation record at proposal did provide descriptions of effects of reclamation 

activities. The specific text in question on page 6 of the HRS documentation record at proposal states that 

the mine property consisted of “approximately 2,656 acres of the facility which were disturbed and 

contained three open pits that were between 200 and 300 feet deep, 32 waste dumpsand [sic] 23 protore 

stockpiles.” [emphasis added] And, page 7 of the HRS documentation record at proposal went on to state: 

Reclamation of the Jackpile-Paguate Uranium Mine commenced in 1990. The “preferred 

alternative” reclamation plan incorporated the following: backfilling of the open pit areas 

to at least 10 feet above projected ground water recovery levels using protore and waste 

rock dump material; slope reduction of the upper 15 feet of highwall slopes; recontouring 

and covering of remaining waste rock dumps; completion of arroyo drainage 

improvements and erosion controls; decontamination of those structures to remain, and 

removal/disposal of all non-essential structures; plugging and bulkheading of 

underground ventilation raises and decline portals, respectively; reclamation of 

miscellaneous features such as wells, access roads, rail spurs, drill holes, etc.; property-
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

13 

wide revegetation of disturbed areas; and provision of property security and long-term 

monitoring of reclamation success for a period of not less than 10 years (Ref. 5, p. 12). 

In discussing the waste dumps and protore piles as other possible sources at the Site, page 26 of the HRS 

documentation record at proposal further explains the reclamation activities:

The mine contained 32 waste dumps that account for approximately 48 percent of the 

disturbed area (Ref. 4, p. 61). 

The tops of 17 waste dumps were reclaimed between 1976 and 1979. The tops were 

contoured to a slight slope, water spreading berms were constructed, large boulders were 

pushed into piles, 18 to 24 inches of soil were spread, and the dumps were seeded (Ref. 4, 

p. 69). In later years, as part of the mine reclamation project, the waste dumps were resloped, with those containing Jackpile Sandstone at the surface covered with 3 feet of 

overburden and 16 inches of topsoil. Waste dumps that did not contain Jackpile 

Sandstone were covered with 18 inches of topsoil (Ref. 5, pp. 7, 8). . . . Approximately 

21 million tons of protore, containing 0.02 to 0.059 percent uranium exist at the mine. 

This material was located on the surface in 23 stockpiles dispersed throughout the mine 

(Ref. 4, p. 74). Between 1989 and 1993, these protore stockpiles were moved into the pits 

(North Paguate Pit , South Paguate Pit, and Jackpile Pit) and used as backfill (Ref. 5, pp. 

31, 32). 

As stated above, the wastes and protore generated at Jackpile-Paguate Uranium Mine 

were not removed from the property but left in place and covered. There was no 

impermeable cap placed on top of the backfill other than overburden (material removed 

during surface mining and stockpiled), shale, and topsoil (Ref. 4, p. 64; Ref. 5, pp. 8, 31, 

32). 

Regarding the waste dumps and protore piles, page 26 of the HRS documentation record at proposal also 

makes clear that “these other possible sources were not evaluated separately or used in the scoring of 

the site.” [emphasis added] That is, these waste dumps and piles were not used to directly determine any 

HRS factor values used to calculate the HRS site score. 

Further, as explained in section 3.9, Consideration of Response Actions/Current Conditions, of this 

support document, reclamation or other activities (various mitigation/improvement measures that have 

taken place at the Site) not described in the HRS documentation record at proposal do not affect the HRS 

site score. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.3 Consideration of Manganese Secondary Drinking Water Criteria 

Comment: ARC questioned the inclusion of a comparison of surface water sample results to the EPA’s 

National Secondary Drinking Water standards for manganese in the Site Summary on page 7 of the HRS 

documentation record at proposal. ARC argued the following:

• The National Secondary Drinking Water standard is a “non-enforceable limit intended as a 

guideline to protect aesthetic qualities of drinking water” (citing the CERCLA Compliance with 

Other Laws Manual, pp. 4-8 [August 1988]). 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

14 

• Thus, the manganese concentrations do not pose a threat to human health or the environment. 

• The EPA was arbitrary to rely on this comparison to support listing the Site on the NPL. 

Response: The discussion in the HRS documentation record at proposal comparing previously detected 

surface water manganese levels to National Secondary Drinking Water Standards was presented only for 

the purpose of illustrating the relative magnitude of hazardous substance concentrations found in 

historical investigations at the Site, and is consistent with one of the main purposes of the NPL: to inform 

the public that a site poses sufficient threat to human health and the environment to warrant further 

investigation. These standards and comparisons to them are not relevant to generating an HRS score for 

the Site. Also, these analytical results shown on page 7 of the HRS documentation record at proposal 

were from previous investigations (conducted from 1996-2006) and were not used in establishing source 

contamination or observed releases for the Site, and therefore the EPA did not rely on these data to 

generate the HRS site score.

Furthermore, as described in section 3.4, Danger to Human Health and the Environment, manganese is 

evaluated in the HRS score for this site because manganese is considered a hazardous substance for HRS 

purposes, consistent with CERCLA. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.4 Danger to Human Health and the Environment 

Comment: ARC stated that “there is no human health (or environmental) related concern posed by 

manganese concentrations in surface water recorded at the Site.” 

Response: Inasmuch as this comment questions the inclusion of manganese as a hazardous substance 

eligible to be considered in an HRS evaluation, this implication is incorrect; as explained below, 

manganese qualifies as a hazardous substance under CERCLA and its use in this evaluation is consistent 

with the HRS. 

Demonstrated Risk

The NPL is intended primarily to guide EPA in determining which sites warrant further investigation to 

assess the nature and extent of public health and environmental risks associated with a release of 

hazardous substances, pollutants or contaminants. See 77 FR 15344 (Proposed Rule, Jackpile-Paguate 

Uranium Mine, March 15, 2012); see also 55 FR 51532 (Final Rule, Hazard Ranking System, December 

14, 1990). CERCLA § 105(a)(8)(a) requires EPA to determine NPL priorities among sites based on the 

“relative risk or danger to public health or welfare, or the environment.” The criteria EPA applies to 

determine this relative risk or danger is codified in the HRS, and is the Agency’s primary tool for deriving 

a site score based on the factors identified in CERCLA. The HRS evaluation and score above 28.50 

represents EPA’s determination that the Site may pose a relative risk or danger to human health and the 

environment and warrants further investigation under CERCLA. As part of the standard Superfund 

process, once the Site is on the NPL, the investigations performed to date to characterize the Site will be 

evaluated for completeness, further information will be collected if deemed necessary to adequately 

characterize the risks posed by the Site, and based on this information, a risk assessment decision will be 

made determining what, if any, remedial action is necessary to protect human health and the environment. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

15 

HRS Eligibility of Manganese

As explained below, the HRS identifies any substance that qualifies as a hazardous substance and meets 

eligibility requirements for evaluation under the surface water migration pathway as eligible for 

consideration in HRS scoring; manganese meets these criteria. 

Manganese is a CERCLA Hazardous Substance 

HRS Section 1.1, Definitions, defines hazardous substances as “CERCLA hazardous substances, 

pollutants, and contaminants as defined in CERCLA sections 101(14) and 101(33), except 

where otherwise specifically noted in the HRS.” CERCLA section 101(14) states: 

The term ‘‘hazardous substance’’ means (A) any substance designated pursuant to 

section 311(b)(2)(A) of the Federal Water Pollution Control Act, (B) any element, 

compound, mixture, solution, or substance designated pursuant to section 102 of this Act, 

(C) any hazardous waste having the characteristics identified under or listed pursuant to 

section 3001 of the Solid Waste Disposal Act (but not including any waste the regulation

of which under the Solid Waste Disposal Act has been suspended by Act of Congress), 

(D) any toxic pollutant listed under section 307(a) of the Federal Water Pollution Control 

Act, (E) any hazardous air pollutant listed under section 112 of the Clean Air Act, 

and (F) any imminently hazardous chemical substance or mixture with respect to which 

the Administrator has taken action pursuant to section 7 of the Toxic Substances Control 

Act. . . . [emphasis added] 

40 CFR 302.42 lists hazardous substances that qualify as such under section 102(a) of CERCLA 

as those substances are identified in the statutes referred to in CERCLA section 101(14). 

According to the 40 CFR 302.4 list, manganese compounds are hazardous substances and 

therefore eligible for HRS scoring consideration. (This list indicates that the statutory source for 

designation as a hazardous substance in this instance is section 112 of the Clean Air Act, 

consistent with CERCLA section 101(14) quoted above.) 

Manganese is an Eligible Hazardous Substance for the Surface Water Migration Pathway

For the two surface water migration pathway threats scored, the drinking water threat and human food 

chain threat, the HRS specifies which hazardous substances are eligible for evaluation. HRS Section 

4.1.2.2, Drinking water threat-waste characteristics, states to

[e]valuate the waste characteristics factor category for each watershed based on two 

factors: toxicity/persistence and hazardous waste quantity. Evaluate only those hazardous 

substances that are available to migrate from the sources at the site to surface water in the 

watershed via the overland/flood hazardous substance migration path for the watershed 

(see section 4.1.1.1). Such hazardous substances include: 

• Hazardous substances that meet the criteria for an observed release to surface water 

in the watershed.

• All hazardous substances associated with a source that has a surface water 

containment factor value greater than 0 for the watershed (see sections 2.2.2, 2.2.3, 

4.1.2.1.2.1.1, and 4.1.2.1.2.2.1). 

 

2 The 40 CFR 302.4 list is available at http://www.ecfr.gov/cgi-bin/textidx?c=ecfr&SID=eea576297c24e12601cff27d7803cffe&rgn=div8&view=text&node=40:29.0.1.1.2.0.1.4&idno=40
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

16 

Similarly, when assessing the human food chain threat, HRS Section 4.1.3.2.1, Toxicity/persistence/

bioaccumulation, refers back to HRS section 4.1.2.2 quoted above, stating to “[e]valuate all those 

hazardous substances eligible to be evaluated for toxicity/persistence in the drinking water threat for the 

watershed (see section 4.1.2.2).” 

Pages 34-36 of the HRS documentation record at proposal identify an observed release of manganese to 

surface water in the watershed at the Site. In addition, manganese has been identified in Source 2, as 

shown in analytical results presented on page 23 of the HRS documentation record at proposal3

; pages 21-

22 of the HRS documentation record at proposal show that a containment value of 10 was assigned to 

Source 2. Thus, manganese is eligible for evaluation in the drinking water and human food chain threats 

scored, as it meets both criteria described in HRS Section 4.1.2.2 above (meeting only one of the criteria 

would suffice). See also Carus Chem. Co. v EPA, 395 F.3d 434 (D.C. Cir. 2005) (holding that EPA may 

use any toxicity data from any exposure route [e.g., inhalation] in determining the toxicity factor value for 

a hazardous substance applied to scoring any HRS migration pathway [e.g., the surface water migration 

pathway]). 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.5 Evaluation of Other Pathways 

Comment: Mr. and Ms. Lorenzo commented that 

[t]he hazard ranking score for the Jackpile mine left things out. Only one exposure 

pathway was analyzed, surface water. There is a need for broader analysis, to include, 

e.g., groundwater and air exposure to contaminants. Adding Jackpile to the NPL could 

ensure that additional exposure pathways are analyzed. 

ARC asserted that distribution of contaminants by wind should have been considered at the Site. 

Response: Inasmuch as these comments involve the scoring of HRS pathways other than the surface 

water migration pathway, the HRS does not require scoring all four pathways if scoring those pathways 

does not change the listing decision. For some sites, data for scoring a pathway are unavailable, and 

obtaining these data would be time-consuming or costly. In other cases, data for scoring some pathways 

are available, but will only have a minimal effect on the site score. In still other cases, data on other 

pathways could substantially add to a site score, but would not affect the listing decision. The HRS is a 

screening model that uses limited resources to determine whether a site should be placed on the NPL for 

possible Superfund response. A subsequent stage of the Superfund process, the remedial investigation 

(RI), characterizes conditions and hazards at the site more comprehensively.

To the extent practicable, EPA attempts to score all pathways that pose significant threats. If the 

contribution of a pathway has a minimal effect on the overall score, in general, that pathway will not be 

scored. In these cases, the HRS documentation record may include a brief qualitative discussion to 

present a more complete picture of the conditions and hazards at the site. As a matter of policy, EPA does 

 

3 Manganese was also shown in Source 1 samples in the HRS documentation record at proposal. However, as 

described in section 3.10, Surface Water Pathway Description: Source 1, of this support document, Source 1 has 

been removed from the evaluation of the surface water pathway overland/flood migration component in the HRS 

documentation record at promulgation. Therefore, hazardous substances in Source 1 samples are no longer 

considered at promulgation for the drinking water threat or human food chain threat of the overland/flood migration 

component.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

17 

not delay listing a site to incorporate new data or score new pathways if the listing decision is not 

affected.

The EPA must balance the need to fully characterize a site with the limited resources available to collect 

and analyze site data. For this reason, the EPA generally will not score additional pathways upon 

receiving new data as long as the site still meets the HRS cutoff score. However, any additional data 

characterizing site conditions could provide useful information during the RI. 

At this site, the cover page of the HRS documentation record at proposal states that based on the 

information available at the time, evaluation of the air migration pathway would not affect the decision to 

place the Site on the NPL. Furthermore, it was stated that the ground water migration pathway was not 

scored because, although there was analytical data available supporting an observed release to the 

environment, there was not a sufficient number of targets present that would impact the HRS site score. 

The ground water to surface water migration component of the surface water migration pathway was not 

scored as the surface water overland/flood migration component was sufficient to support placement of 

the Site on the NPL. Therefore, that the ground water and air migration pathways were not scored in the 

HRS evaluation of the Jackpile-Paguate Uranium Mine site does not represent a decision that there is no 

risk associated with these pathways or that the EPA does not intend to investigate these pathways during 

further investigations at the Site.

The HRS is intended to be a “rough list” of prioritized hazardous sites; a “first step in a process – nothing 

more, nothing less” Eagle Picher Indus. v. EPA, 759 F.2d 922, 932 (D.C. Cir. 1985) (Eagle Picher II). 

EPA would like to investigate each possible site completely and thoroughly prior to evaluating them for 

proposal for NPL, but it must reconcile the need for certainty before action with the need for inexpensive, 

expeditious procedures to identify potentially hazardous sites. The courts have found EPA's approach to 

solving this conundrum to be “reasonable and fully in accord with Congressional intent.” Eagle Picher 

Industries, Inc." v. EPA, (759 F.2d 905 (D.C. Cir. 1985) Eagle Picher I).

To the extent that ARC’s comment implies that contamination at the Site has been affected by wind 

deposition of contaminants, this is addressed in section 3.16.6, Effects of Wind Deposition, of this 

support document. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.6 Data Sufficiency for Listing on the NPL 

Comment: ARC made several comments questioning whether the available information used in the HRS 

documentation record at proposal is sufficient for the purposes of listing a site on the NPL, including the 

following assertions: 

• Insufficient sampling was conducted to characterize background areas, source areas, surface 

waters, and other possible sources; further, there is little support for these samples, and they are 

not representative of actual site conditions. 

• Further assessment of whether runoff can migrate from Source 1 pits is needed to establish

probable points of entry (PPEs) and whether the pits contributed to surface water contamination.

• Further assessment of stream systems, ground water, and surface water is needed to support the 

EPA’s description of the surface water pathway and the rivers included as perennial.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

18 

• Storm water runoff samples should have been collected to quantify source contribution of 

hazardous substances to the surface water. 

• Wind deposition should have been investigated to adequately support attribution of contamination 

to the site. 

• Because an HRS documentation record reference stated that contribution of hazardous substances 

from natural sources at the Site could not be ruled out, it is clear the EPA has insufficient 

information for NPL designation of the Site. 

• The EPA must present and take into account evidence of metals concentrations prior to mining 

activities in order to attribute the observed release to mining operations. 

• The EPA should have collected tissue samples to support bioaccumulation factors used. 

Response: The information used to perform the HRS site evaluation is sufficient to support the HRS 

scoring of the Site and its proposal to the NPL. 

The HRS is a screening tool for identifying sites that pose sufficient actual or potential risk to warrant 

further investigation under Superfund, and further assessment will be performed as part of the Superfund 

process that occurs at a separate stage from NPL listing. And, EPA used appropriate levels of data and 

investigation in determining the HRS score for the Site and is in the spirit of the HRS regulation. As 

explained in the preamble in the Federal Register notice promulgating the present HRS (55 FR 51533, 

December 14, 1990), Congress, in discussing the substantive standards against which HRS revisions 

could be assessed, its Conference report on SARA states: 

This standard is to be applied within the context of the purpose for the National Priorities 

List; i.e., identifying for the States and the public those facilities and sites which appear 

to warrant remedial actions. . . .This standard does not require the Hazard Ranking 

System to be equivalent to detailed risk assessments, quantitative or qualitative, such as 

might be performed as part of remedial actions. This standard requires the Hazard 

Ranking System to rank sites as accurately as the Agency believes is feasible using 

information from preliminary assessments and site inspections. . . . Meeting this standard 

does not require long-term monitoring or an accurate determination of the full nature and 

extent of contamination at sites or the projected level of exposure such as might be done 

during remedial investigations and feasibility studies. This provision is intended to ensure 

that the Hazard Ranking System performs with a degree of accuracy appropriate to its 

role in expeditiously identifying candidates for response actions [H.R. Rep. No. 962, 99th

Cong. 2nd Sess. at 199-200 [1986]]. 

The Courts have supported this position in stating: 

The HRS is intended to be a “rough list” of prioritized hazardous sites; a “first step in a 

process--nothing more, nothing less” Eagle Picher Indus. v. EPA, 759 F.2d 922, 932 

(D.C. Cir. 1985) (Eagle Picher II). EPA would like to investigate each possible site 

completely and thoroughly prior to evaluating them for proposal for NPL, but it must 

reconcile the need for certainty before action with the need for inexpensive, expeditious 

procedures to identify potentially hazardous sites. The courts have found EPA's approach 

to solving this conundrum to be “reasonable and fully in accord with Congressional 

intent.” Eagle Picher Industries, Inc. v. EPA, (759 F.2d 905 (D.C. Cir. 1985) Eagle Picher 

I).
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

19 

The sample results and information gathered from the 2010 SI and 2011 ESI events and presented in the 

HRS documentation record at proposal resulted in the collection of data sufficient to evaluate the Site for 

HRS scoring purposes. 

The implications of each of ARC’s comments above as they apply to the HRS scoring of the Site are 

discussed in other sections of the support document; and in each case, the level of information used to 

generate an HRS score is shown to be sufficient and consistent with the HRS: 

• The number of samples collected to characterize sources and determine background levels for 

surface water and ground water is addressed in the following sections of this support document: 

o 3.11, Sources 1 and 2 Characterization: Association of Hazardous Substances 

o 3.12, Waste Quantity

o 3.13, Other Possible Sources: Association of Hazardous Substances

o 3.15, Likelihood of Release: Background and Significant Increase 

o 3.16.3, Ground Water Background Samples for Overland/Flood Component 

o 3.16.4, Consideration of Naturally Occurring Releases 

o 3.21, Ground Water to Surface Water Migration Component: Background 

• Whether runoff can migrate from Source 1 pits to surface water is addressed in section 3.10, 

Surface Water Pathway Description: Source 1, of this support document.

• The perennial nature of surface water at the Site is addressed in section 3.14, Surface Water 

Pathway Description: In-Water Segment, of this support document. 

• The use of storm runoff samples is addressed in sections 3.16.7, Attribution to a Source, and 

3.16.8, Storm Water Runoff Data, of this support document. 

• Wind deposition is addressed in sections 3.5, Evaluation of Other Pathways, and 3.16.6, Effects 

of Wind Deposition, of this support document. 

• The screening of natural sources of contamination and the need for metals concentrations prior to 

mining are addressed in sections 3.16.1, Background Samples Screening of Natural Levels, and

3.16.4, Consideration of Naturally Occurring Releases, of this support document.

• The use of tissue samples to support bioaccumulation factors used is addressed in section 3.19, 

Human Food Chain Threat: Use of Bioaccumulation Value, of this support document. 

These comments result in no change to the HRS score and no change in the decision to place the Site on 

the NPL.

3.7 Liability 

Comment: ARC and Mr. Parkhill made several comments related to the liability for cleanup at the Site.

ARC commented that the Site Summary of the HRS documentation record at proposal was incomplete, as 

it did not mention the December 2, 1986 agreement between the “Pueblo of Laguna (Pueblo) and 

Anaconda Minerals Company (AMC) to terminate all then-existing mine site leases for the Jackpile 

Mine.” Under this agreement, approved by the United States Department of the Interior, the Pueblo of 

Laguna “agreed to perform the final reclamation of the mine site under federal government oversight.” 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

20 

ARC also noted that AMC provided the Pueblo of Laguna with funds “that substantially exceeded the 

Bureau of Land Management reclamation estimate.” 

ARC also provided an example of the deficiencies it asserts are found in the HRS documentation record’s 

Site Summary. ARC argued that the inclusion of 31 waste dumps and 23 protore stockpiles in the Other 

Possible Sources section of the HRS documentation record exemplifies the failure to “analyze or 

describe” the extent the Pueblo managed reclamation project (with the direct involvement of the federal 

government) was consistent with or deviated from the federal government-approved reclamation 

requirements. 

Mr. Parkhill asserted that if the Laguna Pueblo had used the “Best Available Technology” and correctly 

covered the mine waste dumps, the migration of uranium and other metals to ground water or surface 

water would have been prevented. Mr. Parkhill argued that the EPA should inspect the completed 

reclamation work; if determined to be improperly carried out, Mr. Parkhill asserted that the Laguna 

Pueblo should be held responsible for further action and not the “taxpayers and companies who funded” 

the previous work. 

Response: Inasmuch as this comment concerns liability for cleanup of the contamination at this site, 

whether any party may be liable for response costs is not considered when evaluating a site under the 

HRS; liability for cleanup is not established at the time of NPL listing and does not impact the listing 

decision. The NPL serves primarily as an informational and management tool. The identification of a site

for the NPL is intended primarily to guide EPA in determining which sites warrant further investigation 

to assess the nature and extent of the human health and environmental risks associated with the site and to 

determine what CERCLA-financed remedial action(s), if any, may be appropriate. Identification of a site 

for the NPL does not reflect a judgment on the activities of the owner(s), operator(s), or generator(s) 

associated with a site. It does not require those persons to undertake any action, nor does it assign any 

liability to any person. Subsequent government actions will be necessary in order to do so, and these 

actions will be attended by all appropriate procedural safeguards. This position, stated in the legislative 

history of CERCLA, has been explained in the Federal Register (48 FR 40674, September 8, 1983 and 53 

FR 23988, June 24, 1988). 

Regarding responsibility for the selection, completion, and adequacy of past, present, and future remedial 

actions, these are also generally not factors considered in the listing decision. Previous remedial or 

removal actions are only considered in the sense that certain qualifying removals are reflected in a site 

score (see HRS Preamble Section III.Q, 55FR 51567 December 14, 1990 for further detail on what 

constitutes a qualifying removal). EPA does take into account current conditions, including changes in 

site conditions due to all removal and remedial activities, when it considers what CERCLA action, if any, 

is warranted at a site on the NPL. (See also section 3.9, Consideration of Response Actions/Current 

Conditions, of this support document.)

Regardless, the HRS evaluation of the contamination in the watershed at the Site was based on conditions 

at the time of the most recent site investigations (e.g., see References 30 and 35 of the HRS 

documentation record at proposal).

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.8 Future Remediation Effectiveness/Purpose for Listing 

Comment: Mr. Parkhill asserted that because there is natural uranium throughout the area, no site 

remedies will solve the issue of uranium contamination. Mr. Parkhill stated that:
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

21 

[r]eclamation will never completely eliminate this problem because the Morrison 

formation is present throughout the area and contains Uranium and other metals which 

are naturally occurring as small subcommercial lenses or trace amounts of Uranium 

mineralization. Natural erosion and weathering of these low grade mineral occurrences 

are probably the source of all Uranium and other metals contaminants in this area and 

there is no known way to stop this problem. 

Mr. Parkhill concluded that “[i]t appears that most of the Uranium contaminants are naturally occurring 

and that further reclamation work at the Jackpile Mine and Paguate Mine would be a huge waste of 

taxpayers' money.” 

Response: The NPL listing itself does not represent a finding that remedial action is necessary or will be 

taken; decisions on conducting response actions are made during the RI, when more information is 

collected (and contributions of hazardous substances from naturally occurring sources would be taken 

into account). Consistent with CERCLA, the Agency has in place an orderly procedure for identifying 

sites where releases of substances addressed under CERCLA have occurred or may occur, placing such 

sites on the NPL, evaluating the nature and extent of the threats at such sites, responding to those threats, 

and deleting sites from the NPL. The purpose of the initial two steps is to develop the NPL, which 

identifies for the States and the public those sites that appear to warrant remedial action (56 FR 35842, 

July 29, 1991). The evaluation or RI/FS phase involves onsite testing to assess the nature and extent of 

the public health and environmental risks associated with the site and to determine what CERCLA-funded 

remedial actions, if any, may be appropriate. After a period of public comment, the Agency responds to 

those threats by issuing a Record of Decision which selects the most appropriate alternative. The selected 

remedy is implemented during the remedial design/remedial action phase. Finally, the site may be deleted 

from the NPL when the Agency determines that no further response is appropriate. 

Also, as further explained in sections 3.15, Likelihood of Release: Background and Significant Increase, 

and 3.16, Likelihood of Release: Attribution, of this support document, an observed release of hazardous 

substances has been correctly identified, consistent with the HRS, and some portion of the significant 

increase in hazardous substances is attributable to the Site (and therefore not all naturally occurring). The 

HRS documentation record has identified that the HRS site score is sufficient to warrant NPL listing and 

further investigation. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.9 Consideration of Response Actions/Current Conditions 

Comment: ARC and Mr. Parkhill asserted that the EPA did not present the current conditions of the Site 

in the HRS evaluation, and that the EPA did not consider or correctly present in the HRS documentation 

record the various mitigation/improvement measures that have taken place at the Site.

ARC provided multiple comments related to the consideration of current conditions at the Site at 

proposal: 

• The Site Summary of the HRS documentation record at proposal was incomplete, as it did not 

mention the December 2, 1986 agreement between the “Pueblo of Laguna (Pueblo) and 

Anaconda Minerals Company (AMC) to terminate all then-existing mine site leases for the 

Jackpile Mine.” Under this agreement, approved by the United States Department of the Interior, 

the Pueblo of Laguna “agreed to perform the final reclamation of the mine site under federal 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

22 

government oversight.” This reclamation project was called the Jackpile-Paguate Reclamation 

Project. 

• AMC provided the Pueblo of Laguna with funds “that substantially exceeded the Bureau of Land 

Management reclamation estimate.” 

• The Site Summary of the HRS documentation record at proposal did not provide an analysis or 

description of whether the reclamation project was consistent with or deviated from DOIapproved reclamation requirements, and therefore is incomplete. 

• The Site Summary text on page 6 of the HRS documentation record at proposal describing 

disturbed acreage, pits, waste dumps, and protore stockpiles was noted as accurately describing 

site conditions before the reclamation work, but not afterwards. The site description would need 

to be corrected to depict current site conditions following reclamation activities implemented by 

the Pueblo of Laguna, with the approval of federal agencies. 

• The listing of 31 waste dumps and 23 protore stockpiles in the Other Possible Sources section of 

the HRS documentation record at proposal was questionable, as it appears to suggest this reflects 

current site conditions, and a “number of the protore stockpiles were placed in one or more of the 

mine pits, and 23 protore stockpiles are no longer present on the site.” 

• The Site Narrative at proposal included “unsubstantiated statements” that have the “unfortunate 

potential to exaggerate the observed level of impacts and unnecessarily alarm the public about the 

potential risks associated with the Jackpile Mine site.” 

Mr. Parkhill asserted that during a visit to the Jackpile Mine in 1981, he observed that the “open pit mine 

and all of the underground mine workings” were “completely dry.” Mr. Parkhill stated that based on the 

lack of any standing water being present, the mine “is completely above the water table and could not 

have been the source of Uranium or any other metals that were leached out of the rock to become 

contaminants of the surface or groundwater.” 

Response: The reclamation activities were considered in the HRS evaluation of the Site and in the 

decision to list the Site on the NPL. Despite movement of waste and protore during reclamation actions, 

the HRS sources, Source 1 and Source 2, of hazardous substances and releases (and threat of future 

releases) from those sources are still present at the Site and may still require remedy under CERCLA; 

and, the HRS score at promulgation based on Source 2 and related releases qualifies the Site for the NPL. 

The effectiveness of the response actions that were already undertaken will be considered at a separate 

stage of the Superfund process when determining what further actions, if any, are needed at the Site.

The EPA generally considers removal actions during the scoring process when it has documentation that 

clearly demonstrates there is no remaining release or potential for a release that could cause adverse 

environmental or human health impacts4

. This approach is reasonable as it ensures that the risk posed by 

released hazardous substances not abated by the removal action can be properly evaluated by the EPA. 

Comments regarding reclamation actions do not claim that any specific source has been completely 

removed or that releases to the surface water pathway have been addressed. Also, Source 2 is not 

completely contained in the surface water migration pathway according to the HRS (a fact not challenged 

by commenters); and, as further discussed in section 3.22, Ground Water to Surface Water Migration 

Component: Presence of Water in Pits, of this support document, were Source 1 pits and the waste within 

them evaluated in the ground water to surface water migration component of the surface water migration 

 

4 This position is consistent with OSWER Directive #9345.1-25, April 4, 1997, titled “Revision to OSWER NPL 

Policy ‘The Revised Hazard Ranking System: Evaluating Sites After Waste Removals’ Publication No. 9345.1-

03FS, October 1991.”
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

23 

pathway, they would not be considered contained according to the HRS and therefore continue to pose a 

possible threat. Therefore, risk to the public and environment still exists based on previous releases and 

the potential for future releases from the sources at the Site. Accordingly, based on the fact-specific 

circumstances in this rulemaking, consistent with its policy quoted above, the reclamation actions 

discussed by the commenter result in no change to the HRS site score. 

Furthermore, regarding the conditions at the Site and the effects of reclamation activities, page 7 of the 

HRS documentation record at proposal notes that

[i]n September 2007, a ROD [Record of Decision] Compliance Assessment for JackpilePaguate Uranium Mine was completed by OA Systems Corporation to determine if the 

post-reclamation had met the requirements of the ROD. This report concluded that 

reclamation of the mine was still not complete as several non-compliant and 

potentially non-compliant issues still needed to be addressed (Ref. 5, pp. 80 to 92). 

[emphasis added]

Reference 5 cited in the above quote is the September 2007 ROD Compliance Assessment; pages 80-92 

of that document summarize the conclusions and recommendations of the assessment related to issues 

found to be not compliant with the 1986 ROD, including – but not limited to – the following: 

• Additional water table elevations monitoring is needed to ensure pit bottoms backfill is at least 10 

feet above projected ground water recovery levels. Ponded water in the pits should be analyzed to 

assess any risk posed by hazardous substances present.

• Some long stretches of terracing in pits cause chronic blow-outs caused by the pressure head of 

built up water along terrace berms, and the issue should be evaluated for possible solutions.

• Fencing is not sufficient to prevent sheep grazing at the pit bottoms (where there may be risk of 

radionuclide/heavy metal uptake into plants). Additional pit bottom monitoring and risk 

assessment should be performed to identify any effects on the natural resources for grazing of 

domestic animals and wildlife. 

• Although not indicative of non-compliance with the ROD, erosion occurring at the toes of several 

waste piles moved back from the rivers may expose waste material, posing a risk to humans, 

animals, and water quality in the Rio Moquino. A hydraulic analysis and erosion study should be 

performed to identify areas requiring additional protection. 

• Blocked drainages north of the FD-I and F dumps remained blocked, consistent with the ROD. 

However, resulting ponded water may present a physical and/or chemical/radiological threat to 

grazing animals; the water should be sampled and related threats assessed.

• To comply with the ROD, a final gamma radiation survey should be conducted. 

• Heavy metal uptake by vegetation should be monitored in the pit bottoms. 

• A downgradient boundary well in the Jackpile Sandstone specified by the ROD was not installed.

• Data gaps exist in various water monitoring activities specified by the ROD.

• A risk assessment should be carried out to evaluate threats from gross-alpha, radium-226, and 

uranium in water samples before resource and land use planning takes place.

Thus, information concerning past reclamation activities was contained in the HRS documentation record

package, and was considered by EPA; in addition, several aspects of the Site which may pose a risk (and 

for which remedies were prescribed in the 1986 ROD) have not been addressed. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

24 

Regarding the presence of water in the pits, as mentioned in section 3.22, Ground Water to Surface Water

Migration Component: Presence of Water in Pits, of this support document, the HRS documentation 

record at proposal clearly identifies that since the end of mining activities, ground water levels in the pits 

have rebounded. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.10 Surface Water Pathway Description: Source 1 

Comment: ARC and Mr. Parkhill questioned the inclusion of Source 1 as a source of hazardous 

substances to surface water via overland runoff. Specific arguments presented included: 

• An assertion by ARC that the pits are closed basins and cannot release contaminants to surface 

water via runoff. 

• ARC’s comment that the EPA has not included drainage studies to evaluate runoff from the pits 

to surface water. 

• An observation by ARC that the open pits have been covered with fill, top soil and to some extent 

have been re-vegetated. 

• A question by ARC on the applicability of the overland flow segments and probable points of 

entry for Source 1, based on the pits’ nature as closed basins. 

• An assertion by Mr. Parkhill that the pits were dry in the past, and therefore unlikely to contribute 

uranium to surface water. 

• Pointing to statements in HRS documentation record Reference 35 (indicating gross alpha, gross 

beta, and radium analytical data were not fully validated – radium results are used in the 

association of hazardous substances with Source 1), ARC challenged the legitimacy of use of this 

data in the HRS evaluation for the Site. 

Response: After consideration of these comments, the EPA has determined that currently available data 

do not document an overland flow migration path from the Source 1 pits to the rivers. Documenting such 

a path would require further data collection. Because removing Source 1 from scoring does not affect the 

Site score, the EPA has decided not to pursue further data collection at this time, and to instead remove 

Source 1 from scoring evaluations for the overland/flood component of the surface water pathway in the 

HRS documentation record at promulgation. The EPA believes this is reasonable because the HRS is 

primarily a screening tool for identifying sites that pose sufficient actual or potential risk to warrant 

further investigation. Questions concerning a possible overland flow migration path from the Source 1 

pits to the rivers may be investigated at the RI/FS stage of the Superfund process. 

Source 1 therefore no longer contributes to any of the scoring factors used in evaluating the Site score in 

the HRS documentation record at promulgation. However, Source 1 remains an eligible source for the 

ground water to surface water migration component of the surface water migration pathway, which is 

described but not scored in the HRS documentation record at promulgation (i.e., the ground water to 

surface water component and Source 1 are detailed in the HRS documentation record at promulgation, but 

do not contribute to any scoring factors or the Site score). 

As Source 1 is no longer scored for the overland/flood migration component, the Source 1 source 

hazardous waste quantity value and hazardous substances (including radium) available to migrate from 

Source 1 to surface water via the overland/flood component are no longer considered in the calculation of 

the waste characteristics factor category values for the drinking water threat or human food chain threat. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

25 

See section 3.12, Waste Quantity, of this support document for an explanation of the effects on waste 

quantity. As explained in sections 3.25.1, Drinking Water Threat Waste Characteristics, and 3.25.2, 

Human Food Chain Threat Waste Characteristics, of this support document, this results in no change to 

waste characteristics factor category values and no change to the Site score at promulgation. As shown in 

these sections, the Site score remains above 28.50 based only on Source 2 evaluated for the surface water 

pathway overland/flood migration component (along with the observed release by direct observation at 

Source 2 and the observed release by chemical analysis downstream of Source 2), qualifying the Site for 

listing on the NPL. 

Because Source 1 is no longer evaluated for the overland/flood migration component, PPEs from Source 

1 to surface water described on page 32 of the HRS documentation record at proposal (PPEs 1, 2, and 4) 

have been removed from the HRS evaluation at promulgation. Only PPE 3 from Source 2 remains, and 

the resulting target distance limit (TDL) has been reduced to reflect this (as detailed on page 32 and 

Figure A-4 of the HRS documentation record at promulgation). The 15-mile TDL measurement at 

promulgation begins at PPE 3 for Source 2, and the end of the TDL at promulgation is approximately 1.1 

miles upstream of the end of the TDL at proposal (i.e., the difference between the point from which the 

beginning of the 15 miles was measured at proposal – PPE4 – and the point from which it is measured at 

promulgation – PPE 3). This change has no effect on the targets evaluated (i.e., targets evaluated as 

subject to actual Level II contamination and targets evaluated as subject to potential contamination in the 

HRS documentation record at proposal remain the same in the HRS documentation record at 

promulgation). 

Also, as Source 1 is no longer evaluated for the overland/flood migration component, the release samples 

RP-JM-SW and RP-JM-SW-110420 (in the Rio Paguate, upstream of the rivers’ confluence) are no 

longer considered in the scoring evaluation of the overland/flood migration component. These samples

were previously scored observed release samples in the HRS documentation record at proposal, but are 

now only described as non-scored elements in the HRS documentation record at promulgation as part of 

the non-scored ground water to surface water migration component. However, if the ground water to 

surface water migration component were scored, these samples would represent an observed release for 

that component; the significant increase in hazardous substances identified in those samples would be 

attributable to Source 1 North and South pits, waste materials in contact with the Rio Paguate5

, and 

historical runoff from the North and South pits over the course of their mining. The removal of samples 

RP-JM-SW and RP-JM-SW-110420 from evaluation as evidence of an observed release for the 

overland/flood migration component means that the segment of Rio Paguate from those samples to the 

confluence of the rivers is no longer considered part of the zone of actual contamination for the 

overland/flood migration component. This change results in no effects on targets scored for the 

overland/flood migration component. 

Source 1 remains an eligible source for the ground water to surface water migration component of the 

surface water migration pathway (a component described in the HRS documentation record at proposal, 

but not scored); there is ample evidence presented in the HRS documentation record at proposal to show 

that there is interchange between water in the pits, ground water, and surface water bodies. Therefore, 

Source 1 remains described and characterized in the HRS documentation record at promulgation as an 

eligible site source.

 

5 See page 13 of Reference 7 of the HRS documentation record at proposal, which explains that within the mine 

boundaries, the Rio Paguate was relocated and the new channel was constructed of compacted backfill. See also, 

page 2838 of Reference 35 of the HRS documentation record at proposal, which notes that the Rio Paguate flows 

over waste rock between the North and South Paguate pits. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

26 

As shown in the sections of this support document discussed above, these comments and the resulting 

changes in the HRS evaluation of the Site result in no change to the Site score, and no change in the 

decision to place the Site on the NPL. 

3.11 Sources 1 and 2 Characterization: Association of Hazardous 

Substances

Comment: ARC asserted that inadequate samples were collected from source areas to sufficiently 

represent actual site conditions. Specifically, ARC challenged the collection and use of one solid waste 

sample from each of the three pits and the waste dump to characterize more than 300 acres of “source”.

ARC stated that further background and source area sampling must be conducted to develop a 

“technically valid HRS score”. 

Response: Sources 1 and 2 are adequately characterized in the HRS documentation record at proposal, 

meet the HRS definition of a source, and have been shown to have associated hazardous substances, 

consistent with the HRS6

. The HRS does not specify the number of samples required to characterize the 

hazardous substances present within a source. In fact, sampling is not required. Instead, as explained 

below, the HRS only requires the following: identifying the sources at the site containing hazardous 

substances, and documenting the hazardous substances associated with a source. 

HRS section 1.1, Definitions, defines a source for HRS purposes as

[a]ny area where a hazardous substance has been deposited, stored, disposed, or placed, 

plus those soils that have become contaminated from migration of a hazardous substance. 

Sources do not include those volumes of air, ground water, surface water, or surface 

water sediments that have become contaminated by migration, except: in the case of 

either a ground water plume with no identified source or contaminated surface water 

sediments with no identified source, the plume or contaminated sediments may be 

considered a source.

In identifying sources at a site, HRS Section 2.2.1, Identify sources, states:

For the three migration pathways, identify the sources at the site that contain hazardous 

substances.

HRS Section 2.2.2, Identify hazardous substances associated with a source, states:

For each of the three migration pathways, consider those hazardous substances 

documented in a source (for example, by sampling, labels, manifests, oral or written 

statements) to be associated with that source when evaluating each pathway.

Page 14 of the HRS documentation record at proposal describes Source 1 as follows: 

Mining operations at the Jackpile-Paguate Uranium Mine resulted in approximately 2,656 

acres of surface disturbance, of which the open pits accounted for approximately 1,015 

 

6 Note that, as explained in section 3.10, Surface Water Pathway Description: Source 1, of this support document, 

although Source 1 and hazardous substances associated with Source 1 are no longer evaluated for the purposes of 

the surface water migration pathway overland/flood component, Source 1 remains an eligible source for the ground 

water to surface water migration component of the surface water pathway.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

27 

acres (Ref. 4, pp. 24, 59). The location of this source is depicted on Figure A-2 and 

features of the open pit can be found in References 28 and 29. 

Mining operations were conducted from 1953 through early 1982 from three open pits, 

Jackpile, North Paguate, and South Paguate that were between 200 and 300 feet deep. 

Open pit mining was conducted predominantly with large front-end loaders and haul 

trucks. The uranium ore was segregated according to grade and stockpiled for shipment 

to the mill. Overburden and ore-associated waste was placed in the mined-out areas of the 

pits as backfill (Ref. 4, p. 21; Ref. 5, p. 184; Ref. 28). 

The Jackpile, North Paguate, and South Paguate open pits make up approximately 40 

percent of the total disturbed acreage at the mine (see Figure A-2 and References 28 and 

29). During the later years of mining, some overburden was placed into the mined-out 

portions of the pits. Approximately 101 million tons of backfill composed principally of 

ore-associated waste with some overburden have been returned to the pits (Ref. 4, p. 56, 

69). The southern portion of the Jackpile Pit and the South Paguate Pit received most of 

this material. There were no requirements to keep records on the radiological content of 

the backfill material (Ref. 4, p. 69). 

Page 21 of the HRS documentation record at proposal describes Source 2 as follows: 

Mining operations at the Jackpile-Paguate Uranium Mine resulted in approximately 2,656 

acres of surface disturbance (Ref. 4, pp. 56, 59). The only waste dump sampled and 

evaluated for this source is identified as Waste Dump V (Ref. 29). The mine contained 32 

waste dumps that account for approximately 48 percent of the disturbed area (Ref. 4, p. 

61). The location of Waste Dump V is depicted on Figure A-2 and the location of all the 

waste dumps can be found in References 28 and 29. 

The tops of 17 waste dumps were reclaimed between 1976 and 1979. The tops were 

contoured to a slight slope, water spreading berms were constructed, large boulders were 

pushed into piles, 18 to 24 inches of soil were spread, and the dumps were seeded (Ref. 4, 

p. 69). In later years, as part of the mine reclamation project, the waste dumps were resloped, with those containing Jackpile Sandstone at the surface covered with 3 feet of 

overburden and 16 inches of topsoil. Waste dumps that did not contain Jackpile 

Sandstone were covered with 18 inches of topsoil (Ref. 5, pp. 7, 8). 

As stated above, the wastes generated at Jackpile-Paguate Uranium Mine were not 

removed from the property but left in place and covered with overburden. There was no 

impermeable cap placed on top of the backfill other than overburden (material removed 

during surface mining and stockpiled) and topsoil (Ref. 4, p. 64; Ref. 5, p. 8). In addition, 

radiological analytical results from the ESI show elevated concentrations of gross alpha 

and gross beta (Ref. 35, pp. 3, 30, 33). 

Pages 15-18 of the HRS documentation record at proposal identify several hazardous substances in 

Source 1 (chromium, cobalt, manganese, radium-226, radium-228, thorium-230, uranium-234, uranium235, and uranium-238, vanadium, and zinc). The following samples are presented:
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

28 

Source 1 Characterization Samples

Sample Description

JM-SED-02 North Paguate Pit solid waste sample, March 2010

JM-SW-02 North Paguate Pit liquid waste sample, March 2010

NPOP20E North Paguate Pit subsurface source sample, April 2011

JM-SS-01 South Paguate Pit solid waste sample, March 2010

SPOP35 South Paguate Pit subsurface source sample, April 2011

JM-SS-05 Jackpile Pit solid waste sample

JPOP41S Jackpile Pit subsurface source sample, April 2011

Pages 22-23 of the HRS documentation record at proposal identify hazardous substances in Source 2 

(manganese, uranium-234, uranium-235, uranium-238, and vanadium) in March 2010 sample JM-SS-03. 

Furthermore, although not required by the HRS, at least two samples were collected from each Source 1 

pit as shown in Source 1 characterization data in the HRS documentation record at proposal. And, several 

hazardous substances were detected across multiple Source 1 samples. For example: 

• Chromium was detected in 4 of 7 samples, and in all 3 pits 

• Cobalt was detected in 2 of 7samples, both in the North Paguate Pit

• Manganese was detected in 5 of 7 samples, and in all 3 pits

• Vanadium was detected in 3 of 7 samples, in the North Paguate Pit and Jackpile Pit 

• Zinc was detected in 2 of 7 samples, both in the North Paguate Pit

And, uranium isotopes (234, 235, and 238) were detected in all 7 Source 1 samples presented. This 

indicates that the combined waste materials and overburden placed in the Source 1 pits is similar across 

the pits (which is reasonable given these materials came from similar historical processes at the facility).

Thus, samples from each Source 1 pit and the Source 2 waste dump were presented, documenting the 

presence of hazardous substances in these sources, consistent with HRS requirements; moreover, both 

sources meet the HRS definition of source as an “area where a hazardous substance has been deposited, 

stored, disposed, or placed.” The characterization of Source 1 and Source 2 in the HRS documentation 

record at proposal is consistent with the HRS; further determination of the exact nature and extent of the 

sources will be carried out in other stages of the Superfund process following NPL listing. 

Regarding background samples, if the commenter was implying background samples should have been 

used in associating hazardous substances with Source 1 and Source 2, there is no such HRS requirement. 

Pages 14 and 21 of the HRS documentation record at proposal identify the contents of the Source 1 piles 

as protore and waste and the contents of Source 2 as waste rock. These sources are classified as piles, and 

pages 15-16 and 22 of the HRS documentation record at proposal describe samples used to characterize 

the sources as waste samples; background samples are not needed for waste samples when associating 

hazardous substances with a source. The HRS only requires background samples to identify background 

levels for the purposes of establishing an observed release (see HRS Table 2-3) – not for the association 

of hazardous substances with a source. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

29 

3.12 Waste Quantity 

Comment: ARC challenged the hazardous waste quantity factor value of 1,000,000 assigned for the 

drinking water and human food chain threats of the overland/flood migration component as an 

overestimate. This comment was based on ARC’s other assertions that

• too few samples have been collected to adequately characterize the sources; and, 

• it is inappropriate to include portions of the pits as Source 1 if runoff from those areas may not 

enter surface water. 

Response: The overland/flood migration component waste quantity value has been revised at 

promulgation to reflect the removal of the consideration of Source 1 from this component (as explained in 

section 3.10, Surface Water Pathway Description: Source 1, of this support document). However, the 

waste quantity for Source 2 is estimated consistently with the HRS. The resulting overland/flood 

migration component waste quantity factor value for the drinking water threat and human food chain 

threat becomes 10,000. 

As detailed in section 3.11, Sources 1 and 2 Characterization: Association of Hazardous Substances, of 

this support document, Source 2 is adequately characterized in the HRS documentation record at 

proposal, meets the HRS definition of a source, and is shown to have associated hazardous substances, 

consistent with the HRS. 

HRS section 4.1.2.2.2, Hazardous waste quantity, states to “[a]ssign a hazardous waste quantity factor 

value for the watershed as specified in section 2.4.2.” HRS section 2.4.2, Hazardous waste quantity, 

contains the directions used to determine waste quantity for the dump: 

Evaluate the hazardous waste quantity factor by first assigning each source (or area of 

observed contamination) a source hazardous waste quantity value as specified below. 

Sum these values to obtain the hazardous waste quantity factor value for the pathway 

being evaluated. 

HRS Section 2.4.2.1, Source hazardous waste quantity, states:

For each of the three migration pathways, assign a source hazardous waste quantity value 

to each source (including the unallocated source) having a containment factor value 

greater than 0 for the pathway being evaluated . . . 

For all pathways, evaluate source hazardous waste quantity using the following four 

measures in the following hierarchy:

• Hazardous constituent quantity. 

• Hazardous wastestream quantity.

• Volume. 

• Area.

HRS Section 2.4.2.1.4, Area, gives direction on determining the area value for a source: 

Evaluate the area measure using the area of the source (or the area of the area of the 

observed contamination). Based on this area, designated as A, assign a value to the area 

measure as follows:
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

30 

• For the migration pathways, assign the source a value for area using the 

appropriate Tier D equation of Table 2-5. . . . 

HRS Section 2.4.2.1.5, Calculation of source hazardous waste quantity value, states to: 

Select the highest of the values assigned to the source (or area of observed 

contamination) for the hazardous constituent quantity, hazardous wastestream quantity, 

volume, and area measures. Assign this value as the source hazardous waste quantity 

value. Do not round to the nearest integer.

HRS Section 2.4.2.2, Calculation of hazardous waste quantity factor value, then states to:

Sum the source hazardous waste quantity values assigned to all sources (including the 

unallocated source) or areas of observed contamination for the pathway being evaluated 

and round this sum to the nearest integer, except: if the sum is greater than 0, but less 

than 1, round it to 1. Based on this value, select a hazardous waste quantity factor value 

for the pathway from table 2–6. 

The estimate of waste quantity for Source 2 is based on the area of the pile – not on the amount and 

location of hazardous substances. Regarding the level of sampling and characterization of Source 2 and 

effects on waste quantity, if there is enough information available to determine the mass of all CERCLAeligible hazardous substances in a source, the hazardous constituent quantity measure may be evaluated 

(as shown in the quote from HRS Section 2.4.2.1, Source hazardous waste quantity, above, and detailed 

further in HRS Section 2.4.2.1.1, Hazardous constituent quantity). However, page 23 of the HRS 

documentation record at proposal explains that this is not possible: 

Information on the exact measure (in pounds) of individual hazardous substances in this 

source is not available to evaluate Tier A, hazardous constituent quantity. The number of 

samples collected is not statistically representative of the range of concentrations 

throughout the source. Therefore, it is not possible to adequately determine a hazardous 

constituent quantity for Source 2 with reasonable confidence (Ref. 1, Section 2.4.2.1.1). 

Scoring proceeds to the evaluation of Tier B, hazardous wastestream quantity (Ref. 1, 

Section 2.4.2.1.2). 

Similarly, page 23 of the HRS documentation record at proposal explains that there is insufficient 

available information to evaluate the two other measures (hazardous wastestream quantity and volume) of 

source hazardous waste quantity offered by HRS Section 2.4.2.1, Source hazardous waste quantity. 

Therefore, Source 2 is evaluated on the basis of the area measure, consistent with the HRS.

For Source 2, pages 24-25 of the HRS documentation record at proposal assign an area of 566,280 square 

feet, an area assigned value of 43,560, and a source hazardous waste quantity value of 43,560 (these 

values were not challenged by ARC). 

As shown on pages 48 and 50 of the HRS documentation record at promulgation, and as further detailed 

in section 3.25, Waste Characteristics (and its subsections), of this support document, the hazardous waste 

quantity factor value at promulgation is therefore assigned as 10,000, based on Source 2, which is 

consistent with the HRS. (See sections 3.25.1, Drinking Water Threat Waste Characteristics, and 3.25.2, 

Human Food Chain Threat Waste Characteristics, of this support document, which explain that this 

hazardous waste quantity factor value results in no change to waste characteristics factor category values

or the Site score at promulgation.) 
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31 

 

This comment results in no change to the HRS site score and no change in the decision to place the Site 

on the NPL. 

3.13 Other Possible Sources: Association of Hazardous Substances 

Comment: ARC asserted that insufficient sampling was conducted to adequately characterize the other 

possible sources identified in the HRS documentation record at proposal. 

ARC took issue with the following statement on page 26 of the HRS documentation record at proposal: 

Other possible sources associated with the Jackpile-Paguate Uranium Mine site include 

31 waste dumps and 23 protore stockpiles. Due to the large area of the Jackpile mine, 

individual samples could not be collected from these possible source areas. Therefore, 

these other possible sources were not evaluated separately or used in the scoring of the 

site. However, the hazardous substances associated with these possible sources are 

expected to be the same as the scored sources as they resulted from the same mining 

activities.

ARC asserted that the EPA’s expectation that the 31 other waste dumps “contain the same hazardous 

substances as the one sampled waste dump” is “unfounded and should be deleted.” ARC further stated 

that the content of a waste dump can vary; therefore, it is critical to understand the variability to evaluate 

a release. ARC continued that “[l]imited data may not reflect the actual variation and could incorrectly 

indicate a possible release”. 

ARC also challenged the context of the placement of this statement, as it “suggests 31 waste dumps and 

23 protore stockpiles are present at the Jackpile Mine today.” ARC questioned whether this reflects 

current conditions at the Site, noting “that a number of the protore stockpiles were placed in one or more 

of the mine pits, and 23 protore stockpiles are no longer present on the site.” 

Response: The information presented in the “Other Possible Sources” section of the HRS documentation 

record at proposal is sufficient to identify that the sources listed in this HRS documentation record section 

meet the HRS definition of a source, as is discussed below. Additionally, these possible sources were not 

used in the HRS scoring evaluation. Instead, the information conveyed in the section is meant to inform 

the public about additional possible non-scored sources of hazardous substances connected with the Site, 

and which may be investigated later in the Superfund process. 

Section 1.1, Definitions, of the HRS defines a source as:

Any area where a hazardous substance has been deposited, stored, disposed, or placed, 

plus those soils that have become contaminated from migration of a hazardous substance. 

Sources do not include those volumes of air, ground water, surface water, or surface 

water sediments that have become contaminated by migration, except: in the case of 

either a ground water plume with no identified source or contaminated surface water 

sediments with no identified source, the plume or contaminated sediments may be 

considered a source.

Thus, for a source to be identified for HRS purposes the HRS does not require the source to still be 

present – only that a hazardous substance “has been” deposited, stored, disposed, or placed in that area. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

32 

HRS Section 2.2.2, Identify hazardous substances associated with a source, gives instructions for 

associating a hazardous substance with a source. It does not require sampling each source. It states: 

For each of the three migration pathways, consider those hazardous substances 

documented in a source (for example, by sampling, labels, manifests, oral or written 

statements) to be associated with that source when evaluating each pathway. In some 

instances, a hazardous substance can be documented as being present at a site (for 

example, by labels, manifests, oral or written statements), but the specific source(s) 

containing that hazardous substance cannot be documented. For the three migration 

pathways, in those instances when the specific source(s) cannot be documented for a 

hazardous substance, consider the hazardous substance to be present in each source at the 

site, except sources for which definitive information indicates that the hazardous 

substance was not or could not be present. 

The HRS documentation record at proposal does clearly provide a rationale for associating hazardous 

substances with these other possible sources. Page 26 of the HRS documentation record at proposal states 

that “the hazardous substances associated with these possible sources are expected to be the same as the 

scored sources as they resulted from the same mining activities.” Thus, although the concentrations of 

hazardous substances in the combined materials in each dump/pile may vary, it is reasonable that the 

hazardous substances associated with the waste dumps and protore stockpiles may be the same as those 

found in Sources 1 and 2. 

Furthermore, the Other Possible Sources section on page 26 of the HRS documentation record at proposal 

makes clear that these sources have no effect on HRS site score, noting:

Due to the large area of the Jackpile mine, individual samples could not be collected from 

these possible source areas. Therefore, these other possible sources were not evaluated 

separately or used in the scoring of the site. [emphasis added]

Regarding the comment that the HRS documentation record at proposal mistakenly implies that “31 waste 

dumps and 23 protore stockpiles are present at the Jackpile Mine today,” this is not correct. On the subject 

of the waste dumps, page 26 of the HRS documentation record at proposal states: 

The mine contained 32 waste dumps that account for approximately 48 percent of the 

disturbed area (Ref. 4, p. 61). 

The tops of 17 waste dumps were reclaimed between 1976 and 1979. The tops were 

contoured to a slight slope, water spreading berms were constructed, large boulders were 

pushed into piles, 18 to 24 inches of soil were spread, and the dumps were seeded (Ref. 4, 

p. 69). In later years, as part of the mine reclamation project, the waste dumps were resloped, with those containing Jackpile Sandstone at the surface covered with 3 feet of 

overburden and 16 inches of topsoil. Waste dumps that did not contain Jackpile 

Sandstone were covered with 18 inches of topsoil (Ref. 5, pp. 7, 8). [emphasis added] 

And on the subject of the protore piles, page 26 of the HRS documentation record at proposal states:

Approximately 21 million tons of protore, containing 0.02 to 0.059 percent uranium exist 

at the mine. This material was located on the surface in 23 stockpiles dispersed 

throughout the mine (Ref. 4, p. 74). Between 1989 and 1993, these protore stockpiles 

were moved into the pits (North Paguate Pit, South Paguate Pit, and Jackpile Pit) and 

used as backfill (Ref. 5, pp. 31, 32). [emphasis added] 
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33 

The HRS documentation record at proposal clearly acknowledges that the materials from the waste dumps 

and protore piles have been modified and moved to other on-site locations during reclamation activities. 

However, the materials contained within the original 31 waste dumps and 23 protore stockpiles were not 

removed from the property, but instead were modified in some way (e.g., covered with overburden and 

topsoil and slopes were modified), or used as backfill in the Source 1 pits. (Page 26 of the HRS 

documentation record at proposal notes that “the wastes and protore generated at Jackpile-Paguate 

Uranium Mine were not removed from the property but left in place and covered.”) Therefore, the 

potential threat from a release of hazardous substances from these “other possible sources” materials may 

not have been completely addressed, and may still pose a risk at the Site. Additionally, it is not 

demonstrated that remediation carried out at the Site has addressed all hazardous substance migration 

from these sources that may have occurred prior to the modification of these sources, and this previously 

migrated contamination may still pose a risk.

Further investigation at a separate step in the Superfund process (such as the Remedial 

Investigation/Feasibility Study) will determine the need, if any, for additional remediation of these “other 

possible sources.”

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.14 Surface Water Pathway Description: In-Water Segment 

Comment: ARC asserted that a statement on page 31 of the HRS documentation record describing the Rio 

Paguate as an ephemeral stream that is intermittently dry conflicts with the last paragraph of Section 1.1 

of the ESI Revised Conceptual Site Model (included in Reference 35 of the HRS documentation record at 

proposal), which describes the Rio Paguate and Rio Moquino as perennial water bodies. ARC stated, 

“[t]hese conflicting descriptions related to basic site hydrology appear in two documents, written in the 

same month.” ARC asserted that this “highlights EPA’s lack of understanding of the hydrology of these 

two stream systems,” requiring “further technical assessment of the stream systems and the interaction of 

groundwater and surface water . . . to support HRS scoring and potential NPL designation.” 

Response: The HRS documentation record at proposal is correct in its description of the streams; the Rio 

Moquino and Rio Paguate are perennial at and upstream of the mine, and the Rio Paguate becomes an 

ephemeral stream south of the mine.

In describing surface water bodies eligible for evaluation in the HRS surface water migration pathway, 

HRS Section 4.0.2, Surface water categories, states in relevant part: 

For HRS purposes, classify surface water into four categories: rivers, lakes, oceans, and 

coastal tidal waters.

Rivers include: 

• Perennially flowing waters from point of origin to the ocean or to coastal tidal 

waters, whichever comes first, and wetlands contiguous to these flowing waters. . 

. . 

• Intermittently flowing waters and contiguous intermittently flowing ditches only 

in arid or semiarid areas with less than 20 inches of mean annual precipitation.

HRS Section 4.0.2, Surface water categories, considers water bodies as either perennial or intermittent, 

and does not further classify some intermittent streams as ephemeral. As set out below, the HRS 
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34 

documentation record in this case describes the Rio Paguate as ephemeral and intermittent. Thus, 

“ephemeral” streams are reasonably considered “intermittent” for HRS evaluation purposes for this site; 

this is consistent with the HRS concern regarding surface water as a migration pathway to carry 

hazardous substances (even if ephemeral streams only flow for limited periods, they may still transmit 

hazardous substances).

Page 31 of the HRS documentation record at proposal describes the Rio Moquino and Rio Paguate, 

stating:

The mine facility and surrounding areas are drained by Rio Paguate and Rio Moquino. 

The Rio Paguate flows from headwaters located approximately 10 miles above the mine 

facility, through Bear Canyon, into the watershed that covers much of the eastern flank of 

Mt. Taylor. The source waters originate through seeps from Quaternary basalts capping 

Mesa Chivato, as well as Quaternary alluvium along the canyon. The Rio Moquino flows 

from headwaters located approximately 3.5 miles above the mine facility in Seboyeta 

Canyon. Like the Rio Paguate, the source waters originate through seeps from Cretaceous 

sandstones, Quaternary basalt and alluvium in the upper reaches of the watershed (Ref. 

35, pp, 2753, 2813, and 2877). The Rio Paguate is joined by the Rio Moquino near the 

center of the mine facility. Below this confluence, the Rio Paguate flows southeasterly 

into Paguate Reservoir before joining the Rio San Jose 5 miles south of the mine facility 

(Ref. 4, p. 101). The Rio Paguate has been rechanneled for more than 2,000 feet 

downstream of its entrance to the mine facility (Ref. 4, p. 101). The Rio Moquino has 

been extensively modified over a 4,000-foot segment immediately above its confluence 

with the Rio Paguate. Waste material has been dumped into the original channel on both 

sides, straightening the course of the meandering stream (Ref. 4, p. 102). At the mine 

facility, both streams usually flow all year (perennially); however, south of the mine 

facility, the Rio Paguate acts as an ephemeral stream becoming intermittently dry

(Ref. 4, p. 103). [emphasis added]

For HRS purposes, in areas in which the average annual rainfall is less than 20 inches, 

eligible rivers include those that have been determined to be intermittently flowing water 

and contiguous intermittently flowing ditches (Ref. 1, Sec. 4.02). The average annual 

rainfall at the Jackpile-Paguate Uranium Mine facility is approximately 9 to 12 inches 

(Ref. 22, pp. 15-16). 

Thus, the Rio Moquino and Rio Paguate – both the perennial and intermittent (including ephemeral) 

portions – qualify as rivers eligible for HRS scoring, consistent with the HRS. 

Section 1.1 of the ESI Revised Conceptual Site Model included in Reference 35 mentioned by the 

commenter does indeed generally refer to the streams as perennial, stating:

The perennial rivers Rio Moquino and Rio Paguate bisect the site near its center. The Rio 

Moquino flows southeasterly into the Rio Paguate within the site, and the Rio Paguate 

continues to flow south of the site through the Paguate Reservoir and joins the Rio San 

Jose approximately one mile southwest of the reservoir. 

However, pages 102 and 103 of Reference 4 (a 1986 Jackpile-Paguate Uranium Mine Reclamation 

Project Environmental Impact Statement from the U.S. Department of the Interior) cited in the quoted text 

of the HRS documentation record at proposal confirm specifically that the Rio Paguate becomes 

intermittently dry south of the mine, stating that: 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

35 

The mean daily discharge of the Rio Paguate at the south end of the mine is 1.2 cubic feet 

per second (cfs), about half of which is supplied by surface discharge of ground water 

(base flow). Both the Rios Paguate and Moquino lose water from the points where they 

enter the mine to near their confluence. This loss is probably a response to dewatering of 

the mine. In the area of the confluence, both streams gain water from ground water 

discharge. Measurements at various times have shown that the streams gain between 43 

and 135 gallons per minute (gpm) as they run through the minesite, while at other times 

they show a net loss of 83 gpm. . . . At the minesite, both streams usually flow all year 

(perennially); however, below the minesite, the Rio Paguate becomes intermittently dry 

(it is ephemeral).

Furthermore, text from the same ESI Revised Conceptual Site Model included in Reference 35 mentioned 

by the commenter supports the intermittent nature of the Rio Paguate south of the mine. Page 2772 of 

Reference 35 (in section 2.5.2 of the ESI Revised Conceptual Site Model) notes that: 

Cross section J-J’ intersects Rio Paguate just inside the southern site boundary, near the 

RP-02 sampling point [about halfway between the southern mine border and the Paguate 

Reservoir as shown on page 41 of Reference 35]. Wells MW-2 and MW-6 are screened 

in the Alluvial Aquifer, which rests against Bushy Basin bedrock through this area. The 

wells are far enough from the intersection of the river to make it difficult to determine 

from the cross section whether the river is gaining or losing water; however, the surface 

water sampling team reported that Rio Paguate was dry at this location during the 

2011 ESI event7

. It is therefore probably reasonable to state that Rio Paguate loses water 

through this interval, at least in the waning stages of the high-flow season. [emphasis 

added] 

Therefore, the HRS documentation record at proposal is correct in describing the streams as perennial 

upstream of the site and Rio Paguate as ephemeral and intermittent south of the mine.

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.15 Likelihood of Release: Background and Significant Increase 

Comment: ARC asserted that the number and location of surface water background samples was not 

adequate to determine background levels for the Site and did not accurately represent site conditions. 

ARC claimed that “HRS requirements for establishing background concentrations have been largely 

ignored,” referring to the draft HRS Guidance Manual, Interim Final, November 1992, Section 5.1, 

Establishing an Observed Release and Observed Contamination, Consideration for Background, and 

Section 5.2, Selecting Appropriate Background Samples. ARC contended that “there is no evidence in the 

HRS Documentation Record that proper background surface water sampling was performed to determine 

if an observed release of Isotopic U or Mn from the mine site has occurred.” 

 

7 See also pages 41, and 57-58 of Reference of the HRS documentation record at proposal, which show photographs 

of sampling location RP-02 (at Rio Paguate about halfway between the southern mine boundary and the Paguate 

Reservoir), documenting a dry streambed in April 2011. And, see the field data entry sheet on page 9 of Reference 

36 of the HRS documentation record at proposal, showing a note that the stream was dry at location RP-02 in April 

2011. 
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ARC concluded that the observed release factor category value of 550 is an “overestimation based on 

limited sampling and does not represent actual site conditions.” ARC argued that further background 

sampling is needed to generate a technically valid HRS score. 

Response: EPA applied the HRS to determine background levels. The HRS documentation record at 

proposal contains sufficient background sample data to determine background levels for the purpose of 

establishing an observed release of manganese and uranium isotopes in surface water, consistent with the 

HRS and its purpose as a screening tool. Three valid background samples for each sampling event were 

used to establish observed releases for the Site. In its comments regarding the number of background 

samples, ARC appears to have confused the purpose of a background sample in establishing an observed 

release by chemical analysis, assuming the purpose of the background samples is to show the increase in 

contaminant levels is not due to other sources (i.e., establish attribution). One purpose of establishing a 

background level is to establish that there is a significant increase in contaminant concentrations between 

the background levels and that in release samples. Background samples may also be (but are not 

necessarily) used to establish attribution, which is a separate step in the HRS evaluation process.

These points are detailed in the following subsections:

• HRS Requirements 

• HRS Documentation Record Evaluation 

o Description and Number of Background Samples 

o Background Similarity to Observed Release Samples

o Similar Background Samples’ Concentrations Indicate They Are Representative of the 

Area

• Summary

Comments regarding the cause of the significant increase are addressed in section 3.16, Likelihood of 

Release: Attribution, of this support document and its subsections. 

HRS Requirements

The HRS does not identify requirements (such as specific numbers of background samples) or define 

conditions for establishing background levels of contaminants. The HRS addresses background only in 

the context of identifying an observed release of a hazardous substance to the environment by chemical 

analysis. HRS Section 4.1.2.1.1, Observed release, contains the directions used to establish an observed 

release:

Establish an observed release to surface water for a watershed by demonstrating that the 

site has released a hazardous substance to the surface water in the watershed. Base this 

demonstration on either: 

• Direct observation:

.... 

• Chemical analysis:

- Analysis of surface water, benthic, or sediment samples indicates that the 

concentration of hazardous substance(s) has increased significantly 

above the background concentration for the site for that type of sample 

(see section 2.3).

- Limit comparisons to similar types of samples and background 

concentrations – for example, compare surface water samples to 

surface water background concentrations.
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37 

- For benthic samples, limit comparisons to essentially sessile 

organisms.

- Some portion of the significant increase must be attributable to the site to 

establish the observed release, except: when the site itself consists of 

contaminated sediments with no identified source, no separate attribution 

is required. 

If an observed release can be established for a watershed, assign an observed release 

factor value of 550 to that watershed, enter this value in Table 4-1, and proceed to section 

4.1.2.1.3. 

HRS Section 2.3, Likelihood of release, states in relevant part:

Establish an observed release either by direct observation of the release of a hazardous 

substance into the media being evaluated (for example, surface water) or by chemical 

analysis of samples appropriate to the pathway being evaluated (see sections 3, 4, and 

6). The minimum standard to establish an observed release by chemical analysis is 

analytical evidence of a hazardous substance in the media significantly above the 

background level. Further, some portion of the release must be attributable to the site. 

Use the criteria in Table 2–3 as the standard for determining analytical significance.

HRS Table 2-3 states that if a sample measurement is greater than or equal to the SQL, an observed

release is established:

• If the background concentration is not detected (or is less than the detection 

limit), an observed release is established when the sample measurement equals or 

exceeds the sample quantitation limit.

• If the background concentration equals or exceeds the detection limit, an 

observed release is established when the sample measurement is 3 times or more 

above the background concentration. 

Specific to identifying an observed release of radionuclides, HRS Section 7.1.1, Observed 

release/observed contamination, states:

For radioactive substances, establish an observed release for each migration pathway by 

demonstrating that the site has released a radioactive substance to the pathway (or 

watershed or aquifer, as appropriate); establish observed contamination for the soil 

exposure pathway as indicated below. Base these demonstrations on one or more of the 

following, as appropriate to the pathway being evaluated: 

. . . 

Analysis of radionuclide concentrations in samples appropriate to the pathway (that is, 

ground water, soil, air, surface water, benthic, or sediment samples):

-For radionuclides that occur naturally and for radionuclides that are ubiquitous in the 

environment: 

--Measured concentration (in units of activity, for example, pCi per kilogram 

[pCi/kg], pCi per liter [pCi/1], pCi per cubic meter [pCi/m3 ]) of a given 

radionuclide in the sample are at a level that:

---Equals or exceeds a value 2 standard deviations above the mean sitespecific background concentration for that radionuclide in that type of 

sample, or 

---Exceeds the upper-limit value of the range of regional background 

concentration values for that specific radionuclide in that type of sample.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

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--Some portion of the increase must be attributable to the site to establish the 

observed release (or observed contamination), and

--For the soil exposure pathway only, the radionuclide must also be present at the 

surface or covered by 2 feet or less of cover material (for example, soil) to 

establish observed contamination. 

Thus, background levels are used for the purpose of identifying a significant increase in hazardous 

substances. The HRS also specifies, as shown in above quotes, that background samples should be similar 

in type to release samples. 

HRS Documentation Record Evaluation 

At this site, as discussed below, background samples were used to establish the background levels. The 

locations of the background samples were chosen to be upstream of the mine operations, or far 

downstream8

 of the mine operations, and thus representative of conditions if the mining area were not 

present. (The EPA agrees, however, that these background samples do not reflect natural levels of the 

released substances in that the natural sources are collocated with the mine operations; thus, attribution is 

not established solely by these background samples.) 

Pages 34-38 of the HRS documentation record at proposal contain the rationale for establishing 

background levels and a significant increase in hazardous substance concentrations in surface water at the 

Site. Pages 39-42 of the HRS documentation record establish an observed release in several samples – 

that these sample concentrations meet arithmetic HRS significant increase criteria was not challenged by 

the commenter. 

Description and Number of Background Samples 

Page 34 of the HRS documentation record at proposal discusses the background samples used in 

establishing an observed release by chemical analysis for the Site: 

Background sediment and surface water samples were collected from the locations listed 

below to investigate whether a release from the facility could be established (Ref. 8, Ref. 

19; Ref. 35, p. 118). 

• Rio Moquino - Two background sediment samples and two surface water samples 

were collected from Rio Moquino during the March 2010 and April 2011 sampling 

events (RM-SW-BG, RM-SED-BG, RM-SW-BG-110419, RM-SED-BG-110419) 

immediately upstream of the Jackpile-Paguate Uranium Mine before confluence with 

the Rio Paguate. The background sediment sample and surface water samples 

collected from Rio Moquino is compared to facility-related sediment and surface 

water samples collected from Rio Moquino, Rio Paguate and the Paguate Reservoir.

• Rio Paguate – Two background sediment samples and two surface water samples 

were collected from Rio Paguate (during the March 2010 and April 2011 sampling 

events (RP-SW-BG, RP-SED-BG, RP-SW-BG-041911, RP-SED-BG-041911) 

immediately upstream of the Jackpile-Paguate Uranium Mine before confluence with 

the Rio Moquino. The background sediment sample and surface water samples 

 

8 Background sample MD-SW-110420 is approximately 12 miles downstream of PPE 3, and about 5 miles 

downstream of the farthest downstream observed release sample PR-SW-01 (see Figure A-5B) of the HRS 

documentation record at proposal), and outside of the influence of the Site.
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39 

collected from Rio Paguate is compared to site-related sediment and surface water 

samples collected from Rio Moquino, Rio Paguate, and the Paguate Reservoir.

• Mesita Diversion – One sediment sample (MD-SW-110420) was collected off the 

Rio San Jose from an irrigation diversion ditch in April 2011 to determine regional 

background levels and was used in standard deviation background calculations for 

radionuclide concentrations from the Rio Moquino, Rio Paguate and Paguate 

Reservoir.

Page 35 of the HRS documentation record at proposal notes: 

According to the QASPs [quality assurance sampling plans] for the property, the Rio 

Moquino and Rio Paguate background sampling locations were collected immediately 

upstream of the Jackpile-Paguate Uranium Mine for the purposes of collecting samples 

unaffected by the mine facility and to establish background concentrations of the local 

area (Ref. 30, p. 23; Ref. 35, p. 118; Figures A-5A, A-5B).

Thus, for each of the two investigations from which data is used to establish observed releases (the March 

2010 EPA SI and April 2011 EPA ESI), three background samples were collected: 

• The March 2010 EPA SI included one surface water sample from each river upstream of the 

mine, plus one field duplicate from the Rio Paguate. 

• The April 2011 EPA ESI included one surface water sample from each river upstream of the 

mine, plus one sample several miles downstream of the mine from the Mesita Diversion where 

water is collected from the Rio San Jose. 

Page 36 of the HRS documentation record at proposal notes that in setting the background level used for 

comparison with 2010 EPA SI manganese observed release results, the highest of the three 2010 EPA SI 

background sample results was used. Page 38 of the HRS documentation record at proposal presents 

uranium isotope background concentrations and the calculated observed release criteria – two standard 

deviations above the mean – consistent with HRS Section 7.1.1, Observed release/observed 

contamination. (Note that observed release concentrations shown on page 41 of the HRS documentation 

record at proposal clearly meet these criteria, which is a fact not challenged by the commenters.)

Background Similarity to Observed Release Samples

Regarding similarity between the background and observed release samples, page 35 of the HRS 

documentation record at proposal states: 

The background samples (surface water and sediment) and the samples collected to 

demonstrate an observed release were all collected during the same time frames during 

the same sampling events (Ref. 36, p. 4). [Comparison of sample collection dates shown 

on pages 36-40 of the HRS documentation record at proposal shows that background and 

observed release samples in each of the 2010 EPA SI sample set and 2011 EPA ESI 

sample set were collected within two-day periods.] The samples were collected by the 

same field teams during the same sampling events, following the same sample collection 

protocols and methodologies. Background samples were collected from similar locations, 

were from similar media, same depth, under the same hydrological conditions and flow, 

used the same sampling methods, preservation, and handling and were all collected 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

40 

during the same weather conditions as the observed release samples (Ref. 35, pp. 87-96; 

Ref. 36, pp. 7-16). 

Thus, background samples and release samples within each investigation were sufficiently similar to 

ensure the increase was not due to sample differences (and, no issues related to sample differences 

documented by the commenters). 

Similar Background Samples’ Concentrations Indicate They Are Representative of the Area

The background samples presented are geographically separated from each other and outside the direct 

influence of the mine (that is, upgradient of the mine, or several miles downgradient of the mine); yet, 

they still contain similar concentrations of hazardous substances, showing that the background levels for 

the streams are characteristic of the area. The March 2010 EPA SI background surface water samples 

from the Rio Moquino and Rio Paguate showed comparable manganese concentrations; similarly, the 

April 2011 EPA ESI background surface water sample from the downstream Mesita diversion exhibited 

isotopic uranium levels similar to those measured in the upstream Rio Moquino and Rio Paguate 

background samples. These similar concentrations indicate that the background samples were 

representative of the area in which the Site is located. 

Page 36 of the HRS documentation record at proposal presents the March 2010 background sample 

manganese results:

EPA SI Background Surface Water Sample Concentrations – March 2010

Station 

Location Hazardous

Substance

Concentration

(mg/l)1

Reporting 

Limit2 Reference

Rio Moquino

RM-SW-BG Manganese 0.027 0.01 Ref. 19, p. 18; Ref. 20, pp. 

18, 70; Ref. 25, pp. 1 to 5

Rio Paguate

RP-SW-BG Manganese 0.045 0.01 Ref. 19, p. 18; Ref. 20, pp. 

20, 73; Ref. 25, pp. 1 to 5

RP-SW-BGD

(Duplicate) Manganese 0.044 0.01 Ref. 19. p.18; Ref. 20, pp. 

20, 74; Ref. 25, pp. 1 to 5

Notes:

1 mg/l – milligram per liter 2 The definition of the Reporting Limit used by ALS Laboratory Group was not provided in the laboratory package 

(Ref. 20, pp. 758 to 762).

Page 37 of the HRS documentation record at proposal presents the April 2011 background sample 

uranium isotope results:
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

41 

EPA ESI Background Surface Water Sample Concentrations – April 2011

Station Location Hazardous

Substance Concentration Reporting Limit2 Units1 Reference

Rio Moquino

RM-SW-BG-110419

Uranium234

Uranium235

Uranium238 

4.119

0.0996

2.230

0.066

0.019

0.066

pCi/l

pCi/l

pCi/l

Ref. 35, pp. 

744, 774, 1587

Rio Paguate

RP-SW-BG-041911

Uranium234

Uranium235

Uranium238 

6.242

0.216

3.793

0.061

0.018

0.041

pCi/l

pCi/l

pCi/l

Ref. 35, pp. 

747, 778, 1587

Mesita Diversion

MD-SW-110420

Uranium234

Uranium235

Uranium238 

4.858

0.306

2.811

0.054

0.016

0.070

pCi/l

pCi/l

pCi/l

Ref. 35, pp. 

736, 760, 1587

Notes:

1 pCi/l = picocurie per liter 2

 The Reporting Limit is defined as the MDC for uranium by Alpha Spectroscopy and is the net concentration that 

has a specified chance of being detected (Ref. 39, p. 3). 3

 Radiological data were validated by a START-3 Certified Health Physicist with 30 years of radiation 

characterization experience. Data for target analytes meet the definitive data quality objective (Ref. 35, p. 1587, 

Ref. 36, p. 5).

That the background sample locations are spatially separate from each other and outside the influence of 

the Site, yet still show similar manganese and isotopic uranium concentrations, indicates that they 

accurately reflect the surface water background concentrations for the greater area around the mine. Also, 

that the April 2011 EPA ESI background samples’ isotopic uranium concentrations are similar upstream 

and downstream of the mine, coupled with the release sample levels detected in the immediate 

downstream vicinity of the mine, shows that the background samples serve the purpose of site-specific 

background samples which clearly identify a significant increase in isotopic uranium localized at and 

immediately downstream of the mine. 

Summary

The HRS documentation record at proposal contains sufficient background sample data to determine 

background levels for the purpose of identifying a significant increase of hazardous substances – 

consistent with the HRS; there is no need to perform additional background sampling. Regarding the 

commenter’s mention of the draft HRS Guidance Manual, Interim Final, November 1992 (HRS Guidance 

Manual), EPA applied the HRS to determine background levels. The commenter has not pointed to any 

specific recommendation in the draft HRS Guidance Manual with which the EPA has been inconsistent. 

This guidance manual imposes no mandatory requirements on the EPA, and is used on a case-by-case 

basis depending on the facts presented by each individual site, to guide the application of the HRS. Its 

suggestions are meant to guide an HRS evaluator, but do not represent requirements at any site. Sections 

5.1 and 5.2 of that guidance material provide several suggestions on background sample collection for 

surface water (e.g., that background samples should ideally include upstream samples; more than one 

background sample may be appropriate in areas of significant branching or tributary input, in situations 

where the site or migration route is physically complex, to address different meteorological conditions, or 

sites with other potential sources in the vicinity of the site; background and release samples should be 

collected in the same general part of the water body – center, bank, bend, etc.; that background and 

release samples be collected within the same time frame, be of similar type, be exposed to similar 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

42 

environmental conditions). Background samples presented in the HRS documentation record at proposal 

are consistent with these suggestions. 

Furthermore, even if the observed release by chemical analysis were not evaluated (eliminating the need 

for associated background samples), the Site score would not change if based solely on the observed 

release by direct observation identified at Source 2. (While the human food chain threat Level II 

concentrations score would drop to zero, and the food chain individual score would drop from 45 to 20 

[due to absence of a fishery subject to Level II concentrations], the human food chain threat score would 

remain unchanged at 100, the surface water migration pathway score would remain 100.00 [see HRS 

Section 4.1.3.3.1, Food chain individual, and HRS Section 4.1.3.3.2.2, Level II concentrations]).

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.16 Likelihood of Release: Attribution 

Comment: ARC and Mr. Parkhill challenged the attribution of the significant increase in hazardous 

substances found in surface water observed releases to the Site. These challenges were based on several 

assertions:

• Background samples do not adequately address the metals contributed to surface water by 

naturally occurring rock formations in the area.

• Background samples should have been collected during rain events to address contaminants 

contributed by runoff. 

• Background levels have not been established for ground water discharging from the underlying 

Jackpile sandstone and mixing with the surface water. 

• Metals found in surface water are more likely due to natural rock formations in the area rather 

than the site sources. And, the HRS documentation record should have documented uranium and 

manganese levels before mining operations began to show that observed releases are due to 

mining and not natural sources. 

• Elevated metals concentrations in surface water may be due to high evaporation rates in the area.

• The possibility of wind transport and deposition of hazardous substances has not been addressed.

• The observed release was not effectively attributed to site sources.

• Storm water runoff data should have been collected to adequately determine the contaminants 

contributed from any sources.

Response: The hazardous substances, uranium and manganese, are clearly related to the Site and site 

sources, and the HRS documentation record at proposal presents reasonable evidence supporting the

attribution of some portion of the significant increase in hazardous substances found in surface water to 

the Site, consistent with the HRS.

The HRS does not contain specific instruction regarding the methodology for establishing attribution for 

an observed release by chemical analysis. On the subject of attribution for all HRS pathways, however, 

HRS Section 2.3, Likelihood of release, states in relevant part:

Establish an observed release either by direct observation of the release of a hazardous 

substance into the media being evaluated (for example, surface water) or by chemical 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

43 

analysis of samples appropriate to the pathway being evaluated (see sections 3, 4, and 6). 

The minimum standard to establish an observed release by chemical analysis is analytical 

evidence of a hazardous substance in the media significantly above the background level. 

Further, some portion of the release must be attributable to the site. Use the criteria in 

table 2–3 as the standard for determining analytical significance. [emphasis added]

HRS Section 4.1.2.1.1, Observed release, contains specific instructions for identifying an observed 

release to surface water. It directs the scorer to establish an observed release to surface water by 

demonstrating that the site has released a hazardous substance to surface water, based on either direct 

observation or chemical analysis, including addressing the attribution of an observed release by chemical 

analysis to a site: 

Establish an observed release to surface water for a watershed by demonstrating that the 

site has released a hazardous substance to the surface water in the watershed. Base this 

demonstration on either: 

• Direct observation:

–A material that contains one or more hazardous substances has been seen 

entering surface water through migration or is known to have entered surface 

water through direct deposition, or 

–A source area has been flooded at a time that hazardous substances were 

present, and one or more hazardous substances were in contact with the flood 

waters, or

–When evidence supports the inference of a release of a material that contains 

one or more hazardous substances by the site to surface water, demonstrated 

adverse effects associated with that release may also be used to establish an 

observed release.

• Chemical analysis:

- Analysis of surface water, benthic, or sediment samples indicates that the 

concentration of hazardous substance(s) has increased significantly 

above the background concentration for the site for that type of sample 

(see section 2.3).

- Limit comparisons to similar types of samples and background 

concentrations – for example, compare surface water samples to 

surface water background concentrations. 

- For benthic samples, limit comparisons to essentially sessile 

organisms.

- Some portion of the significant increase must be attributable to the 

site to establish the observed release, except: when the site itself consists 

of contaminated sediments with no identified source, no separate 

attribution is required.

Specific to identifying an observed release of radionuclides, HRS Section 7.1.1, Observed 

release/observed contamination, states:

For radioactive substances, establish an observed release for each migration pathway by 

demonstrating that the site has released a radioactive substance to the pathway (or 

watershed or aquifer, as appropriate); establish observed contamination for the soil 

exposure pathway as indicated below. Base these demonstrations on one or more of the 

following, as appropriate to the pathway being evaluated: 

. . . 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

44 

Analysis of radionuclide concentrations in samples appropriate to the pathway (that is, 

ground water, soil, air, surface water, benthic, or sediment samples):

-For radionuclides that occur naturally and for radionuclides that are ubiquitous in the 

environment: 

--Measured concentration (in units of activity, for example, pCi per kilogram 

[pCi/kg], pCi per liter [pCi/1], pCi per cubic meter [pCi/m3 ]) of a given 

radionuclide in the sample are at a level that:

---Equals or exceeds a value 2 standard deviations above the mean sitespecific background concentration for that radionuclide in that type of 

sample, or 

---Exceeds the upper-limit value of the range of regional background 

concentration values for that specific radionuclide in that type of sample.

--Some portion of the increase must be attributable to the site to establish the 

observed release (or observed contamination), and

--For the soil exposure pathway only, the radionuclide must also be present at the 

surface or covered by 2 feet or less of cover material (for example, soil) to 

establish observed contamination. 

It is appropriate and consistent with the HRS requirements at this site to establish attribution by first 

documenting that hazardous substances are present at the Site by showing that the contaminants are 

associated with a site source, and second, by documenting that at least some of the increase in hazardous 

substance levels came from the Site.

Pages 34-38 of the HRS documentation record at proposal contain the rationale for establishing 

background levels and a significant increase in hazardous substance concentrations in surface water at the 

Site. Pages 39-42 of the HRS documentation record establish an observed release in several samples – 

that these sample concentrations meet arithmetic significant increase criteria was not challenged by the 

commenter.

Page 43 of the HRS documentation record at proposal notes that uranium isotopes and manganese 

detected in observed release samples were also found in the site sources:

As part of an environmental assessment of the Jackpile-Paguate Uranium Mine facility in 

March 2010, and April 2011 START-3 collected a total of 7 source samples from former 

open pit and waste dump locations within the mine area including three solid waste 

samples, one liquid waste sample, and three subsurface water samples from within the 

former mine area (Ref. 19, Figure A-5A). The solid waste samples contained uranium238

as high as 367 ug/g and manganese as high as 270 mg/kg. The liquid waste sample 

contained uranium238 as high as 114,131 pCi/l and manganese as high as 4.633 mg/l (see 

Section 2.4.1 of this HRS documentation record). These same contaminants have been 

found as observed release samples in the surface water pathway as high as 78.787 pCi/l 

for uranium238 and 0.25 mg/l for manganese (see Section 2.4.1.2.1.1 of this HRS 

documentation record).

On the many mechanisms by which site-related hazardous substances may have entered surface water, 

page 43 of the HRS documentation record at proposal explains the following:

The sources at the facility are uncontained, and even in places are in the surface water. 

The Rio Paguate has been rechanneled for more than 2,000 feet downstream of its 

entrance to the mine facility (Ref. 4, p. 101; Ref. 31). The Rio Moquino has been 

extensively modified over a 4,000-foot segment immediately above its confluence with 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

45 

the Rio Paguate. Waste material has been dumped into the original channel on both sides, 

straightening the course of the meandering stream (Ref. 4, p. 102). It appears that normal 

practice was to stockpile waste material in the Rio Moquino’s floodplain as records 

indicate that approximately 500,000 tons of material from Waste Dump U on the east 

side of the river were removed during 1982, the last year of mining operations (Ref. 4, p. 

69). Potential hazards resulting from waste dump instability at the mine include rotational 

failures, base translational failures, and foundation spreading (Ref. 4, p. 77). Such waste 

dump failures could expose material and thus present a health and environmental hazard 

(Ref. 4, p. 77). Limited slope stabilization studies were performed on the slope of Waste 

Dump I to evaluate the ability of biodegradable matting to inhibit erosion. Special 

reseeding techniques were performed on the slope of Waste Dump J. The matting and 

special reseeding techniques were unsuccessful; however, it is unknown if slope 

stabilization has actually been performed (Ref. 4, p. 69). Rapid surface water flow from 

flooding of the rivers could expose surface water to sources at the property in addition to 

accelerated erosion of the waste dumps due to the long, steep slopes of the waste dumps 

and potential high-intensity rainfall resulting from summer thunderstorms (Ref. 4, p. 116; 

Ref. 22, p. 2). 

Mine waste enters the surface water pathway via two mechanisms. As discussed above, 

mine waste enters the surface water pathway through direct disposition by overland flow. 

During the EPA ESI conducted April 2011, it has also been demonstrated that mine waste 

also enters the surface water pathway through ground water within the mine pits (see 

Section 2.2 for Source 1 and Section 3). The ground water to surface water mechanism is 

further discussed in Section 4.2 of this report. 

Page 43 of the HRS documentation record at proposal explains why the significant increase in hazardous 

substances is not due to other sites, stating:

There are other mines in the area, including St. Anthony Mine which is approximately 

11,000 feet northeast of Jackpile-Paguate Mine. The St. Anthony Mine does not connect 

to Rio Paguate, Paguate Reservoir or Rio San Jose surface water pathway being evaluated 

(Ref. 3, p. 1, Ref. 19, p.3). Also, background samples collected for Jackpile-Paguate 

Uranium Mine showed low levels (3.86 ppb and 560 ppb) of total uranium and 

manganese (Ref. 20, pp. 18 to 20, 70, 72-74, 79, 86, 87, 557 to 559, and 561 to 563). A 

search of the Toxic Release Inventory database was performed within the zip code of the 

facility location and no other facilities are listed (Ref. 13).

Based on the above information, pages 43-44 of the HRS documentation record at proposal conclude that:

Due to historical operations, one that has demonstrated to cause uranium and manganese 

contamination, combined with the overall lack of containment of the source at the facility 

and the fact that surface water samples meeting observed release criteria are present that 

support uranium and manganese contamination migration from the sources at the facility 

into the surface water pathway, the uranium and manganese contamination in the facility 

can be attributed (wholly or, at least, in part) to the Jackpile-Paguate Uranium Mine 

facility.

Thus, the HRS documentation record at proposal shows that the contaminants found in the significant 

increase are associated with a source at the Site, and establishes that at least some of the increase in these 

hazardous substance levels came from the Site, documenting attribution consistent with the HRS.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

46 

Furthermore, as previously mentioned, even if the observed release by chemical analysis were not 

evaluated, the Site score would not change if based solely on the observed release by direct observation 

identified at Source 2. (While the human food chain threat Level II concentrations score would drop to 

zero, and the food chain individual score would drop from 45 to 20 [due to absence of a fishery subject to 

Level II concentrations], the human food chain threat score would remain unchanged at 100, the surface 

water migration pathway score would remain 100.00 [see HRS Section 4.1.3.3.1, Food chain individual, 

and HRS Section 4.1.3.3.2.2, Level II concentrations]).

Specific challenges to attribution are addressed in the following subsections:

• 3.16.1 Background Samples Screening of Natural Levels

• 3.16.2 Collection of Storm Runoff Background Samples 

• 3.16.3 Ground Water Background Samples for Overland/Flood Component 

• 3.16.4 Consideration of Naturally Occurring Releases 

• 3.16.5 Effects of Evaporation

• 3.16.6 Effects of Wind Deposition

• 3.16.7 Attribution to a Source

• 3.16.8 Storm Water Runoff Data 

3.16.1 Background Samples Screening of Natural Levels

Comment: ARC asserted that the background samples do not adequately address the metals contributed to 

surface water by naturally occurring rock formations in the area. 

ARC stated that 

[t]he Rio Moquino and Rio Paguate flow over mineralized outcrops of the Jackpile 

Sandstone (host rock for the uranium deposit that was mined) that likely contribute 

uranium and other metals to the water. Insufficient consideration was given to the 

contribution of naturally-occurring metals in site waters, as background water sampling 

locations are outside the zone of greater mineralization in the formation. Thus, 

background surface water sampling does not reflect actual site conditions, and interjects 

bias in EPA’s scoring. See, Section 5.1, Consideration for Background and Section 5.2, 

Selecting Appropriate Background Samples, EPA HRS Guidance Manual (November 

1992). 

ARC asserted that the EPA’s “failure to establish a reliable background” calls into question the assigned 

likelihood of release factor category value of 550. 

Response: As explained in section 3.15, Likelihood of Release: Background and Significant Increase, of 

this support document, the HRS documentation record at proposal contains sufficient background sample 

data to determine background levels for the purpose of establishing an observed release in surface water, 

consistent with the HRS. Additionally, to the extent possible, these background samples account for 

metals contributed to the Rio Moquino and Rio Paguate by naturally occurring rock formations through 

which they run.

As further detailed in section 3.15, Likelihood of Release: Background and Significant Increase, of this 

support document, the HRS does not contain requirements (such as specific numbers of background 

samples) or define conditions for establishing background levels of contaminants. The HRS addresses 

background only in the context of identifying an observed release of a hazardous substance to the 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

47 

environment by chemical analysis; the background samples presented in the HRS documentation record 

at proposal fulfill this purpose. 

It is correct that the upgradient sections of Rio Paguate and Rio Moquino (likely including the locations 

of the upgradient background samples) cut through geologic units that are stratigraphically above the 

Jackpile Formation. However, the areas where these rivers cut through the Jackpile Formation generally 

occur within the mine boundaries and have been modified by mining activities; these modifications 

include significant removal of overburden in these areas, as well as replacement of alluvium with minederived material, and some stretches of the streams have been rechanneled and partially lined with mining 

wastes. Therefore, without extensive sampling it may be difficult or impossible to place background 

samples within stretches of the streams cutting through the Jackpile Formation while simultaneously 

avoiding influences of the mining activities and man-modified landscape (and associated concentrations 

of hazardous substances) within the mine boundaries. This level of extensive sampling is not required by 

the HRS. 

Page 2791 of Reference 35 (section 4.4.2 of the ESI Revised Conceptual Site Model) discussed this 

subject, stating:

Exposed surfaces of the Jackpile Sandstone are a probable natural source of uranium into 

the surface water system. Physical and chemical weathering of the Jackpile Sandstone 

would liberate the uranium oxides, which would then enter the surface water system 

when exposed to meteoric water. This process would probably occur slowly, and the area 

of activity would be limited to the naturally exposed wall and some reaction depth into 

the outcrop. Such exposed surfaces are the likely source of the radiation signature that 

drew mining interests to the area in the first place (Owen, et al., 1984).

There are natural Jackpile Sandstone surfaces exposed in the walls of Oak Canyon and a 

few other isolated locations along the mesa walls, but most of these exposures have been 

altered by mining activities within this watershed. The Anaconda Mineral Company 

disturbed approximately 356 million tons of rock, and exposed over 2 square miles of 

Jackpile Sandstone surface in this watershed. Much of this has occurred where the 

Jackpile Sandstone is intersected by Rios Paguate and Moquino. The proportional 

contribution of this increased, anthropogenic exposure, including the increased surface 

area of the waste rock, protore, and tailings piles, is expected to be overwhelmingly 

higher than from the exposed natural surfaces. 

Consequently, it was more appropriate to locate the background samples outside the boundaries of the 

mine to most effectively capture natural metals levels without influence of metals released by the mining 

activities; had the background samples been collected from a portion of the streams cutting through the 

Jackpile Formation (and thus within mine boundaries), the concentrations of hazardous substances 

contributed naturally by the formation would have been eclipsed by the hazardous substance 

concentrations mobilized by effects of the mining activities. Additionally, the upstream background 

samples still screen out any effects of hazardous substances migrating via surface water from upstream 

locations. 

Furthermore, there is evidence of measureable increases in the hazardous substance concentrations in 

surface water as it moves downstream through the Site, likely due to effects of mining activities. At 

sample point RP-JM-SW in the Rio Paguate upstream of the confluence, manganese was found at 0.14 

mg/L (as shown in March 2010 data presented on page 41 of the HRS documentation record at proposal); 

at sample point RP-SW-01 downstream of the confluence, manganese was detected at 0.19 mg/L. More 

importantly, for uranium data, even if upstream release samples RM-JM-SW-110420, RM-JM-SW-02-
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

48 

110420, RP-JM-SW-110420, and RP-JM-SW-01-110420 are used as if they were background samples to 

set observed release criteria, concentrations downstream at RP-SW-01-110420 would still establish an 

observed release. Using the isotopic uranium results presented for RM-JM-SW-110420, RM-JM-SW-02-

110420, RP-JM-SW-110420, and RP-JM-SW-01-110420 presented on page 41 of the HRS 

documentation record at proposal, the following hypothetical observed release criteria (two standard 

deviations above the mean) can be calculated:

Sample

Hazardous 

Substance

Concentration 

(pCi/L)

Sample 

Mean

Standard 

Deviation

Two Standard 

Deviations Above the 

Mean

RM-JM-SW-110420

Uranium-234

37.997

31.80125 4.5395499 40.88035 RM-JM-SW-02-110420 28.334

RP-JM-SW-110420 28.476

RP-JM-SW-01-110420 32.398

RM-JM-SW-110420

Uranium-235

1.54

1.202 0.252086 1.7061719 RM-JM-SW-02-110420 0.961

RP-JM-SW-110420 1.071

RP-JM-SW-01-110420 1.236

RM-JM-SW-110420

Uranium-238

33.431

27.6315 4.620856 36.873212 RM-JM-SW-02-110420 23.591

RP-JM-SW-110420 24.247

RP-JM-SW-01-110420 29.257

And the results for RP-SW-01-110420, as shown on page 41 of the HRS documentation record at 

proposal still exceed these artificially high hypothetical criteria:

Sample

Hazardous 

Substance

Concentration 

(pCi/L)

RP-SW-01-110420 Uranium-234 85.098

RP-SW-01-110420 Uranium-235 3.236

RP-SW-01-110420 Uranium-238 78.787

Therefore, even if the background samples evaluated in the HRS documentation record at proposal were 

replaced with upstream observed release samples as background (which would clearly account for any 

uranium that would be added naturally to surface water), there is an observed release-scale increase at the 

next downstream sampling point. This indicates a strong contribution of hazardous substances from the 

Site in addition to any hazardous substances that could be contributed naturally. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.16.2 Collection of Storm Runoff Background Samples

Comment: ARC argued that background samples should have been collected during rain events to address 

contaminants contributed by runoff. ARC stated that 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

49 

background surface water samples were collected during a period of low flow, which 

calls into question the representation of these samples as actual background samples. 

Proper background surface water sampling requires that samples be collected during 

rainfall events to evaluate surface water run-off from natural undisturbed areas of the site. 

To support this assertion, ARC cited the draft HRS Guidance Manual, Interim Final, November 1992, 

Sections 5.1, Establishing an Observed Release and Observed Contamination, Consideration for 

Background and 5.2, Selecting Appropriate Background Samples. 

Response: Runoff data evidence is not required by the HRS as implied by ARC. Also, as further 

explained in sections 3.15, Likelihood of Release: Background and Significant Increase, and 3.16, 

Likelihood of Release: Attribution, of this support document, the currently used background levels show 

a significant increase in hazardous substances, that some portion of this significant increase is due to the 

Site, and that no other off-site sources in the area call into question this attribution.

For the 2010 EPA SI and 2011 EPA ESI sample sets, the background and observed release samples in 

each set were similar as required by the HRS (as described in section 3.15, Likelihood of Release: 

Background and Significant Increase, of this support document), notably including that 

background/release samples were collected in the same 2-day time frame under similar weather 

conditions. (And, neither background nor release samples were collected during rain events.) Each set of 

samples established a significant increase in hazardous substances at and downstream of the Site, 

consistent with the HRS, and background samples collected during rain events were not necessary. 

Thus, the EPA has been consistent with the HRS in collecting background samples to establish an 

observed release. The HRS does not require the timing of sample collection to coincide with rain events. 

In this situation, it would be unreasonably burdensome and outside the scope of the HRS given the arid 

nature of the Site location and relative infrequency of rain events. Additionally, the draft HRS Guidance 

Manual, Interim Final, November 1992 (HRS Guidance Manual) imposes no mandatory requirements on 

the EPA, and is used on a case-by-case basis depending on the facts presented by each individual site, to 

guide the application of the HRS. Its suggestions are meant to guide an HRS evaluator, but it is not 

mandatory at any site. Furthermore, the commenter has not pointed to any specific recommendation in the 

draft HRS Guidance Manual with which the EPA has been inconsistent; nor can the EPA find such a 

requirement in the referenced guidance material.

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.16.3 Ground Water Background Samples for Overland/Flood Component

Comment: ARC commented on the following statement in section 4.1.1.1, Definition of Hazardous 

Substance Migration Path for Overland/Flood Component, on page 31 of the HRS documentation record 

at proposal: 

The Rio Moquino and Rio Paguate bisect the mine and are in direct contact with the 

sources (Ref. 3, p. 1; Ref. 7, p. 10). Within the mine footprint, ground water in the 

Jackpile sandstone interchanges with water in the Rio Moquino and Rio Paguate through 

the unconsolidated alluvium deposits along the stream channels. The stream deposits act 

as a mixing zone between the surface water in the rivers and the ground water 

discharging from the underlying Jackpile sandstone (Ref. 7, pp. 5, 26). 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

50 

In discussing its concerns with background surface water samples for the Site related to the above text, 

ARC asserted that 

in reference to Comment 189

, proper background levels have not been established for 

groundwater discharging from the underlying Jackpile sandstone and mixing with the 

surface water. Background surface water and groundwater sampling, sufficient to meet 

the substantive requirements of the HRS, must be conducted before a HRS that meets the 

requirements of CERCLA and the NCP can be prepared. 

On a similar subject, Mr. Parkhill commented that ground water in the Morrison Formation is of poor 

quality because of high total dissolved solids (TDS) content, and asserted that some of this ground water 

may be entering the rivers and affecting river water quality. 

Response: To the extent that the commenters were implying that the HRS documentation record should 

have included background ground water samples in the determination of surface water background levels 

for the Site (in order to assess the contribution that ground water-borne naturally occurring metals may 

have on the surface water metals levels), this is not required by the HRS in the determination of surface 

water background levels, and could represent an inappropriate comparison of ground water and surface 

water contradictory to HRS requirements.

The HRS does not require background ground water samples for the purpose of establishing an observed 

release to surface water via the overland/flood migration component; ground water background samples 

are used in the surface water migration pathway only when evaluating the ground water to surface water 

migration component. HRS Section 4.1.2.1.1, Observed release, contains the directions used to establish 

an observed release, and specifies that prospective surface water observed release samples be compared to 

background concentrations set by surface water background samples (not ground water background 

samples):

Establish an observed release to surface water for a watershed by demonstrating that the 

site has released a hazardous substance to the surface water in the watershed. Base this 

demonstration on either: 

• Direct observation:

.... 

• Chemical analysis:

- Analysis of surface water, benthic, or sediment samples indicates that the 

concentration of hazardous substance(s) has increased significantly 

above the background concentration for the site for that type of sample 

(see section 2.3).

- Limit comparisons to similar types of samples and background 

concentrations – for example, compare surface water samples to 

surface water background concentrations. [emphasis added]

 

9 ARC refers to “Comment 18” of its comment document. There is no comment numbered 18 in that document. It 

appears that ARC is referring to its comment 15, in which it claims that the U-234/U-238 ratios observed in ground 

water to surface water migration component background well samples are different than those in ground water 

release samples; ARC concludes that this indicates these ground water well background samples are not similar to 

the ground water release samples and therefore not representative of background conditions for Jackpile Mine. (See 

also section 3.21, Ground Water to Surface Water Migration Component: Background, of this support document, 

which addresses the comment related to U-234/U-238 ratios in ground water.)
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

51 

And, the ground water to surface water migration component of the HRS surface water migration 

pathway specifies that surface water observed releases established for that component be identified as 

described in HRS Section 4.1.2.1.1 quoted above. HRS section 4.2.1.3, Observed release of a specific 

hazardous substance to surface water in-water segment, states:

Section 4.2.2.1.1 specifies the criteria for assigning values to the observed release factor 

for the ground water to surface water migration component. With regard to an individual 

hazardous substance, consider an observed release of that hazardous substance to be 

established for the surface water in-water segment of the ground water to surface water 

migration component only when the hazardous substance meets the criteria both for an 

observed release both to ground water (see section 4.2.2.1.1) and for an observed 

release by chemical analysis to surface water (see section 4.1.2.1.1). [emphasis added]

Also, it may not be scientifically appropriate to compare surface water sample results to ground water 

sample results. The natural contribution of metals in ground water results could be different than that in 

surface waters, as the ground water is in more intimate contact with geologic formations than the surface 

water (which is in contact with a given stream’s banks and bed); in general, the greater surface area of 

rock exposed to a volume of ground water may allow for increased dissolution of metals. Further, other 

chemical differences between ground water and surface water may affect extraction and persistence of 

naturally occurring metals (e.g., pH, oxidation/reduction potential). And, to compare ground water 

background levels to surface water samples, the amount of ground water input to surface water (and the 

corresponding contribution of contaminants) would need to be factored in – evaluations beyond any HRS 

requirements. 

Additionally, natural contributions of uranium from ground water at the Site are unlikely to be significant; 

page 2791 of Reference 35 (section 4.4.1 of the ESI Revised Conceptual Site Model) discussed this 

subject, stating:

Based on historical groundwater sampling data, Jackpile groundwater is an unlikely 

source of natural uranium contamination. Groundwater monitoring wells located upgradient of the site, and screened in the Jackpile Aquifer, consistently yield low uranium 

concentrations and/or activities with respect to down-gradient surface water and 

groundwater sampling locations (see Table 4 and associated references therein). Field 

measurements taken during the 2011 ESI indicate that three background wells installed in 

the Jackpile Aquifer have the lowest dissolved oxygen concentrations of the entire data 

set. In addition, uranium oxide deposition is known to be intimately associated with 

concentrations of organic material, especially in the upper portions of the Jackpile 

Sandstone (Owen, et al., 1984); this organic material may provide additional protection 

of uranium oxides in the undisturbed form. Regardless, uranium oxides do not appear to 

be significantly mobile in the Jackpile Aquifer above the site.

However, even if the ground water background sample results presented on page 58 of the HRS 

documentation record (as part of the ground water to surface water migration component information) 

were compared to surface water observed release sample results, many of the isotopic uranium results 

would meet HRS observed release criteria for radionuclides. Using the isotopic uranium results presented 

for ground water background samples presented on page 58 of the HRS documentation record at proposal, 

the following hypothetical observed release criteria (two standard deviations above the mean) can be 

calculated:
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

52 

Sample

Hazardous 

Substance

Concentration 

(pCi/L)

Sample 

Mean

Standard 

Deviation

2 Standard 

Deviations Above 

the Mean

MW-1 

Uranium-234

3.74

6.0875 3.737248319 13.56199664

MW-7-110419 3.8

MW-8-110419 5.21

MW-RM 11.6

MW-1 

Uranium-235

0.161

0.25375 0.322995743 0.899741486

MW-7-110419 0.062

MW-8-110419 0.059

MW-RM 0.733

MW-1 

Uranium-238

0.826

8.304 14.47817567 37.26035134

MW-7-110419 0.44

MW-8-110419 1.95

MW-RM 30

The surface water isotopic uranium observed release results presented on page 41 of the HRS 

documentation record at proposal are summarized in the table below; those that would meet the 

hypothetical observed release criteria generated from ground water background samples are 

bolded/underlined: 

Station Location Hazardous

Substance

Concentration

(pCi/L)

RM-JM-SW-110420

Uranium-234

Uranium-235

Uranium-238

37.997

1.540

33.431

RM-JM-SW-02-110420

Uranium-234

Uranium-235

Uranium-238

28.334

0.961

23.591

RP-JM-SW-11042010

Uranium-234

Uranium-235

Uranium-238

28.476

1.071

24.247

RP-JM-SW-01-110420

Uranium-234

Uranium-235

Uranium-238

32.398

1.236

29.257

RP-SW-01-110420

Uranium-234

Uranium-235

Uranium-238

85.098

3.236

78.787

 

10 As described in section 3.10, Surface Water Pathway Description: Source 1, of this support document, because 

Source 1 is no longer evaluated for the overland/flood migration component, the release samples RP-JM-SW and 

RP-JM-SW-110420 (in the Rio Paguate, upstream of the rivers’ confluence) are also no longer considered in the 

evaluation of the overland/flood migration component. However, these samples would represent an observed release 

for the ground water to surface water migration component of the surface water pathway, were it scored.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

53 

Station Location Hazardous

Substance

Concentration

(pCi/L)

Uranium-234 17.445

PR-SW-01-110420 Uranium-235 0.565

Uranium-238 14.624

Thus, even if ground water background samples were used to calculate observed release criteria (which is 

not specified by the HRS, and would also likely be scientifically inappropriate), several surface water 

observed release results would still meet observed release levels.

Therefore, the surface water background samples used to establish background levels in the HRS 

documentation record at proposal are sufficient, and consistent with the requirements in the HRS; there is 

no need to consider ground water background samples in establishing an observed release to surface 

water.

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.16.4 Consideration of Naturally Occurring Releases

Comment: ARC and Mr. Parkhill asserted that the metals found in surface water are more likely due to 

natural rock formations in the area rather than the site sources. 

ARC asserted that contaminants in surface water are “almost exclusively attributed to the mining 

operations” in the HRS documentation record at proposal. However, ARC commented that “[t]he Rio 

Moquino and Rio Paguate flow over mineralized outcrops of the Jackpile Sandstone (host rock for the 

uranium deposit that was mined) that likely contribute uranium and other metals to the water.” 

ARC pointed to the following statement from page v in Reference 35 of the HRS documentation record at 

proposal (from the Executive Summary section of the Revised Conceptual Site Model included in the July 

2011 Draft Expanded Site Inspection Report for the Site): 

[w]hile natural sources cannot be completely ruled out, existing data have yet to identify 

a source with the volume and contaminant concentration capable of producing the 

observed impact to surface water and groundwater system.

ARC asserted that “[t]his statement makes it clear that the data which are available and meet HRS quality 

criterion and other available information are insufficient to prepare a valid HRS, much less support EPA’s 

position that the HRS score is sufficient for purposes of NPL designation.” 

ARC also pointed to the following statement on page 31 of the HRS documentation record at proposal: 

The Rio Moquino and Rio Paguate bisect the mine and are in direct contact with the 

sources (Ref. 3, p. 1; Ref. 7, p. 10). Within the mine footprint, ground water in the 

Jackpile sandstone interchanges with water in the Rio Moquino and Rio Paguate through 

the unconsolidated alluvium deposits along the stream channels. The stream deposits act 

as a mixing zone between the surface water in the rivers and the ground water 

discharging from the underlying Jackpile sandstone (Ref. 7, pp. 5, 26). 

In discussing its issues with background surface water samples for the Site related to the above text, ARC 

asserted that 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

54 

in reference to Comment 1811, proper background levels have not been established for 

groundwater discharging from the underlying Jackpile sandstone and mixing with the 

surface water. Background surface water and groundwater sampling, sufficient to meet 

the substantive requirements of the HRS, must be conducted before a HRS that meets the 

requirements of CERCLA and the NCP can be prepared. 

ARC commented on the following statement on pages 43-44 of the HRS documentation record at 

proposal: 

Due to historical operations, one that has demonstrated to cause uranium and manganese 

contamination, combined with the overall lack of containment of the source at the facility 

and the fact that surface water samples meeting observed release criteria are present that 

support uranium and manganese contamination migration from the sources at the facility 

into the surface water pathway, the uranium and manganese contamination in the facility 

can be attributed (wholly or, at least, in part) to the Jackpile-Paguate Uranium Mine 

facility.

ARC asserted that this statement was speculative regarding the origin of uranium and manganese in 

surface water at the Site, and stated that “[t]he HRS Documentation Record must present actual evidence 

of the concentration of uranium and manganese before mining operations commenced for comparison. 

Without such data, EPA’s conclusion is arbitrary, as it is not sufficiently supported by the HRS record.” 

Mr. Parkhill commented that the Jackpile Bed, part of the Morrison Formation, is the member from which 

the uranium was mined at the Jackpile and Paguate mines, and asserted that 

throughout the Jackpile bed there are a large number of zones of small noncommercial 

ore and trace amounts of Uranium and other metals. The basalt flows on the mesa to the 

west of these two mines are the probable source of Arsenic and Uranium that was found 

in the Rio San Jose. 

Mr. Parkhill argued that uranium and other metals naturally occur in sub-commercial lenses or 

trace mineralization in the Morrison Formation, which is present throughout the area; erosion of 

these mineral occurrences is “probably the source of all Uranium and other metals contaminants 

in this area.” 

Response: While natural sources may be contributing some metals to the rivers, the HRS documentation 

record at proposal correctly establishes attribution consistent with the HRS because the hazardous 

substances – uranium and manganese – are clearly related to the Site and sources, and a sufficient 

rationale has been presented showing that some portion of the significant increase of uranium and 

manganese found in surface water is attributable to the Site.

As explained in section 3.16, Likelihood of Release: Attribution, of this support document, the HRS 

documentation record at proposal correctly attributes some portion of the significant increase in 

hazardous substances found in surface water to the Site, consistent with the HRS. (This rationale included 

 

11 ARC refers to “Comment 18” of its comment document. There is no comment numbered 18 in that document. It 

appears that ARC is referring to its comment 15, in which it claims that the U-234/U-238 ratios observed in ground 

water to surface water migration component background well samples are different than those in ground water 

release samples; ARC concludes that this indicates these ground water well background samples are not similar to 

the ground water release samples and therefore not representative of background conditions for Jackpile Mine.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

55 

showing that uranium isotopes and manganese detected in observed release samples were also found in 

the site sources; a description of the many mechanisms by which site-related hazardous substances may 

have entered surface water; an explanation of why the significant increase in hazardous substances is not 

due to other sites; and connecting historical facility practices with contamination.) That this significant 

increase was not instead due to natural sources is further explained in the following subsections:

• Adequacy of Background Samples 

• HRS Documentation Record Reference 35 Conceptual Site Model Assessments

• Summary

Adequacy of Background Samples

Section 3.15, Likelihood of Release: Background and Significant Increase, of this support document, 

explains that the HRS documentation record at proposal contains sufficient background sample data to 

determine background levels for the purpose of establishing an observed release of manganese and 

uranium isotopes in surface water, consistent with the HRS and its purpose as a screening tool.

Section 3.16.1, Background Samples Screening of Natural Levels, of this support document, details why 

to the extent feasible, these background samples account for metals contributed to the Rio Moquino and 

Rio Paguate by naturally occurring rock formations through which they run. This section also explained:

• Regarding the location of the background samples relative to the mineralized zone, it was more 

appropriate to locate the background samples outside the boundaries of the mine to most 

effectively capture natural metals levels without influence of metals released by the mining 

activities; had the background samples been collected from a portion of the streams cutting 

through the Jackpile Formation (and thus within mine boundaries), the concentrations of 

hazardous substances contributed naturally by the formation would have been eclipsed by the 

hazardous substance concentrations mobilized by effects of the mining activities. And, the 

upstream background samples still screen out any effects of hazardous substances migrating via 

surface water from upstream locations.

• Even if the background levels evaluated in the HRS documentation record at proposal were based 

on the most upstream samples taken in the mine area – which would clearly account for any 

uranium that would be added naturally to surface water – there is another significant increasescale elevation in concentration at the next downstream sampling point. This indicates a strong 

contribution of hazardous substances from the Site in addition to any hazardous substances that 

could be contributed naturally. 

Section 3.16.3, Ground Water Background Samples for Overland/Flood Component, of this support 

document, explained why the use of background ground water samples in the determination of surface 

water background levels for the Site is not appropriate, and that natural contributions of uranium from 

ground water at the Site are unlikely to be significant. 

HRS Documentation Record Reference 35 Conceptual Site Model Assessments

The ESI Revised Conceptual Site Model included in Reference 35 of the HRS documentation record at 

proposal provides further evidence that some portion of the significant increase identified in surface water 

is attributable to the Site. Section 4.4 of that model specifically addresses contributions of hazardous 

substances from natural sources. Page 2791 of Reference 35 states:
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

56 

The question then becomes whether or not the uranium contamination observed in 

the surface water, groundwater, and surface sediments is derived from a natural 

source. While it is probably not possible to rule out a natural source for the entire 

increase in uranium activity in surface water and groundwater through the site, it is 

possible to demonstrate that a majority of the contamination is derived from mining 

activities. [emphasis added]

Possible natural sources might include groundwater from the Jackpile Aquifer, naturally 

exposed surfaces of the Jackpile Sandstone, weathered detritus of Jackpile Sandstone comingled with the pre-mining Alluvium, and efflorescent sediments that were deposited by 

evaporation with the Alluvium during the pre-mining era. 

On page 2791 of Reference 35, the ESI Revised Conceptual Site Model addressed uranium contributions 

from ground water to surface water:

Based on historical groundwater sampling data, Jackpile groundwater is an unlikely 

source of natural uranium contamination. Groundwater monitoring wells located upgradient of the site, and screened in the Jackpile Aquifer, consistently yield low uranium 

concentrations and/or activities with respect to down-gradient surface water and 

groundwater sampling locations (see Table 4 and associated references therein). Field 

measurements taken during the 2011 ESI indicate that three background wells installed in 

the Jackpile Aquifer have the lowest dissolved oxygen concentrations of the entire data 

set. In addition, uranium oxide deposition is known to be intimately associated with 

concentrations of organic material, especially in the upper portions of the Jackpile 

Sandstone (Owen, et al., 1984); this organic material may provide additional protection 

of uranium oxides in the undisturbed form. Regardless, uranium oxides do not appear to 

be significantly mobile in the Jackpile Aquifer above the site. [emphasis added]

On the possible contributions of uranium from Jackpile outcrops, the ESI Revised Conceptual Site Model 

on page 2791 of Reference 35 states: 

Exposed surfaces of the Jackpile Sandstone are a probable natural source of uranium into 

the surface water system. Physical and chemical weathering of the Jackpile Sandstone 

would liberate the uranium oxides, which would then enter the surface water system 

when exposed to meteoric water. This process would probably occur slowly, and the area 

of activity would be limited to the naturally exposed wall and some reaction depth into 

the outcrop. Such exposed surfaces are the likely source of the radiation signature that 

drew mining interests to the area in the first place (Owen, et al., 1984). 

There are natural Jackpile Sandstone surfaces exposed in the walls of Oak Canyon and a 

few other isolated locations along the mesa walls, but most of these exposures have been 

altered by mining activities within this watershed. The Anaconda Mineral Company 

disturbed approximately 356 million tons of rock, and exposed over 2 square miles of 

Jackpile Sandstone surface in this watershed. Much of this has occurred where the 

Jackpile Sandstone is intersected by Rios Paguate and Moquino. The proportional 

contribution of this increased, anthropogenic exposure, including the increased 

surface area of the waste rock, protore, and tailings piles, is expected to be 

overwhelmingly higher than from the exposed natural surfaces. [emphasis added]

Regarding the natural weathering of Jackpile Sandstone, the ESI Revised Conceptual Site Model on page 

2792 of Reference 35 states: 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

57 

Weathered Jackpile Sandstone is an unlikely source of significant quantities of 

uranium in the surface water system. The weathering process would include physical 

ablation of the sandstone and fairly rapid chemical leaching of the uranium oxide 

cements into the surface water system. The Jackpile Sandstone is also very friable, so 

coherent sandstone fragments are not likely to survive more than a few hundred feet of 

transport. It is therefore unlikely that any remnant Jackpile Sandstone clasts would 

survive in sufficient quantities to provide a source in the Alluvium capable of affecting 

surface water and/or groundwater chemistries. Added to this is the fact that any place 

where such deposits might have existed would have been deposited in the Alluvium very 

near where the strike of the Jackpile Sandstone is cut by the Rios Paguate and Moquino 

systems. Since this is where mining activities were focused, any significant 

accumulations of deposits would have been scraped out by Anaconda during mining 

operations and replaced with waste rock. [emphasis added]

On potential uranium contribution from efflorescent deposits, the ESI Revised Conceptual Site Model on 

pages 2792-2793 of Reference 35 states: 

Efflorescent deposits are the precipitated salts formed as a result of the evaporation of 

surface and vadose water that contains a high dissolved sediment load. The TDS for 

surface waters collected near the site during the 2011 ESI range from 420 to 3,860 mg/l, 

and the TDS for groundwater samples collected at the site during the same event range 

from 515 to 3,500 mg/l (up to 6,370 mg/l in the Jackpile Pit water). Under oxidizing 

conditions (subaerial and oxic groundwater conditions and pH in the normal range), 

uranium oxides are very soluble, and will only precipitate under evaporitic conditions, 

which occur during periods of low flow. During periods of high-water flow, these 

deposits are quickly re-dissolved and mobilized. Qualitative evidence of this may be 

found in that sediment cores collected during the 2010 SI did not yield significantly 

elevated uranium concentrations, but the targeted surface sampling during the 2011 ESI 

did find significantly elevated uranium activities. Soluble minerals can be transported 

downstream in multiple iterations of dissolution and precipitation. Because of the high 

solubility of these deposits, they are ephemeral and tend to be washed out during periods 

of high rain/ water flow. 

For the efflorescent sediments collected during the 2011 ESI, uranium activities are 

significantly elevated with respect to background in samples collected at three locations. 

These are all surface samples, and therefore unlikely to have survived 60 years of 

seasonal flooding. 

The highest activity in sediment (RM-JM = 11.9 picoCuries per kilogram) is reported at a 

location where much of the natural alluvium has been co-mingled with, or replaced with 

waste rock from mining activities. The uranium in these sediments represents new, 

post-mining deposition, not residual, natural efflorescence from the weathering of 

Jackpile Sandstone during pre-mining activities.

It should also be noted that the uranium activities in the sediments are commonly an 

order of magnitude lower than the uranium activities in the co-located water sediments, 

which makes it very difficult to make the argument that these sediments are 

responsible for the observed uranium activities in the surface water and 

groundwater systems. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

58 

It is not possible to completely rule out the existence of residual, pre-mining-era 

efflorescent sediments in the alluvial/surface water system, but their vulnerability to 

dissolution during high-water events makes their survivability in any substantial 

volume that is capable of producing the concentrations of uranium in an active 

fluvial system unlikely. [emphasis added]

Summary

The HRS documentation record at proposal correctly establishes attribution, consistent with the HRS; the 

hazardous substances, uranium and manganese, are clearly related to the Site and sources, and the record 

shows that some portion of the significant increase of uranium and manganese found in surface water is 

attributable to the Site (and is not the result of natural sources).

Regarding the “speculative” nature of the statement on pages 43-44 of the HRS documentation record at 

proposal, clear evidence has been provided that some portion of the uranium and manganese in surface 

water originated at the Site; the statement in question itself identifies that uranium and manganese are 

associated with historical operations and the HRS sources, that the sources are uncontained for HRS 

purposes, and that there has been an observed release of these contaminants in surface water (and there is 

additionally an observed release by direct observation). Regarding the assertion that the EPA must 

provide pre-mining operations concentrations to prove that surface water contaminants came from the 

Site, this is not an HRS requirement.

Regarding the following statement from page v in Reference 35 of the HRS documentation record at 

proposal (the July 2011 Draft Expanded Site Inspection Report for the Site, specifically within the ESI 

Revised Conceptual Site Model included in that report):

While natural sources cannot be completely ruled out, existing data have yet to identify a 

source with the volume and contaminant concentration capable of producing the observed 

impact to surface water and groundwater system.

ARC is incorrect in its comment that this “statement makes it clear that the data which are available and 

meet HRS quality criterion and other available information are insufficient to prepare a valid HRS, much 

less support EPA’s position that the HRS score is sufficient for purposes of NPL designation.” This 

statement is part of the final paragraph in the Executive Summary section of the ESI Revised Conceptual 

Site Model. The paragraph in full states: 

The primary source of uranium in surface and groundwater on-site, and downgradient of, the Jackpile-Paguate Mine Site is thought to be the approximately 356 

million tons of waste rock, tailings, and protore at the site that are in intimate 

contact with the surface water and groundwater system. While natural sources cannot

be completely ruled out, existing data have yet to identify a source with the volume and 

contaminant concentration capable of producing the observed impact to surface water and 

groundwater system. [emphasis added] 

Thus, the statement within its original context meant that the main source of uranium contamination in 

surface water and ground water is waste rock, tailings and protore generated by mine processes; although 

natural sources may contribute to this contamination, they could not cause contamination on the same 

order as the mining wastes. This is consistent with the attribution of the significant release to the Site 

established by the HRS documentation record at proposal. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

59 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.16.5 Effects of Evaporation

Comment: Mr. Parkhill asserted that the Jackpile Mine and Paguate mine might not be the cause of 

elevated uranium levels in the Rio Moquino and Rio Paguate, suggesting that the elevation in 

concentrations are instead likely due to high evaporation rates in the region. 

Response: Regarding Mr. Parkhill’s assertion that the elevation in surface water uranium levels may be 

explained by evaporation rates in the area, this is unlikely for the reasons explained below:

• Several of the 2011 uranium observed release samples are located within and just outside of the 

mine boundaries, approximately 2-3 miles downstream of the background samples. The uranium 

observed release sample locations within the Rio Moquino at the Site (RM-JM-SW-110420 and 

RM-JM-SW-02-110420) contain uranium at levels approximately 7-15 times those in the Rio 

Moquino background sample (RM-SW-BG-110419). Similarly, Rio Paguate samples located in 

the mine boundaries (RP-JM-SW-110420, RP-JM-SW-01-110420, and RP-SW-01-110420) 

contain uranium levels approximately 5-20 times those in the Rio Paguate background sample. It 

is unlikely that this increase is due to evaporation over the relatively short travel course of 2-3 

miles; such an elevation in concentration, if caused by evaporation would require a corresponding 

5-20 times reduction in volume of a given parcel of water due directly to evaporation as it passed 

over those 2-3 miles. And if evaporation were causing this increase in contaminant concentration, 

this concentration effect would be expected to continue to elevate concentrations as the water 

moves further downstream; as explained below, this is not the case. (See background and 

observed release results on pages 36-41 of the HRS documentation record at proposal, and 

sample locations shown on Figure A-5B of the HRS documentation record at proposal.) 

• Background sample MD-SW is located downstream of the Site. The lower levels of uranium in 

this sample contradict a scenario in which evaporation has created the observed release levels.

That is, if evaporation were the dominant process yielding higher uranium concentrations 

downstream of the Site, one would expect concentrations at more downstream locations such as 

MD-SW to be even higher than concentrations at locations closer to the Site (because waters at 

more downstream locations would have experienced a longer period of evaporation since leaving 

the Site). 

• As detailed in section 3.16.1, Background Samples Screening of Natural Levels, of this support 

document, even if upstream observed release samples RM-JM-SW-110420, RM-JM-SW-02-

110420, RP-JM-SW-110420, and RP-JM-SW-01-110420 were used as if they were background 

samples to set observed release criteria, concentrations downstream at RP-SW-01-110420 would 

still meet HRS observed release criteria for radionuclides (two standard deviations above the 

mean of the background sample results). The uranium concentration at RP-SW-01-110420 

increases by a factor of 2 to 3 over concentrations in these upstream samples RM-JM-SW110420, RM-JM-SW-02-110420, RP-JM-SW-110420, and RP-JM-SW-01-110420. The distance 

involved from the hypothetical background locations to RP-SW-01-110420 is only about 1-1.5 

miles, and again the increase is unlikely explained by evaporation over such a short distance.

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

60 

3.16.6 Effects of Wind Deposition

Comment: ARC asserted that the EPA did not consider the possibility of wind transport and deposition of 

hazardous substances in its selection of background samples, stating that “wind can be an active 

component of sediment distribution and should have been . . . evaluated, particularly with respect to 

background samples.” 

Response: Regarding wind deposition, the background samples (particularly the upstream background 

samples that are within one mile of the mine boundaries) and observed release samples would be expected 

to be affected equally by regional wind deposition of naturally occurring hazardous substances. 

To the extent that the commenter is pointing to wind deposition of contaminants originating from the Site 

itself, that would in effect be a demonstration of an observed release from the Site (and the HRS air 

migration pathway could have been evaluated in that case). On the other hand, if the commenter is 

implying the origin of any wind-deposited contaminants is outside the Site, the commenter has provided 

no plausible explanation for why such distant naturally occurring sources would selectively affect 

downstream release locations and not upstream background locations.

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.16.7 Attribution to a Source

Comment: ARC made comments implying that the observed release was not effectively attributed to site 

sources. 

In asserting that the Source 1 pits are closed basins covered with fill, topsoil, and partial revegetation that 

could not contribute contamination to surface water, ARC stated that 

the EPA summarily characterizes these pits as one of the main sources of contamination 

at the Site without technical support. Further assessment is warranted before the HRS 

Documentation Record is finalized to determine whether there is an actual release of 

contaminants from the pits to surface water. 

ARC also claimed that surface water sampling during rain events must be performed “to quantify the

contribution of contaminants from any sources via run-off and direct contact with surface water.” 

Response: Inasmuch as these comments imply that the HRS requires attribution of observed releases by 

chemical analysis to a source, this is not correct. The HRS specifies that an observed release must be 

attributed to a site, not any particular source. And, there is no HRS requirement that evidence be 

presented that a given source has released hazardous substances to the pathway in order to evaluate that 

source for HRS scoring purposes. 

As shown in HRS text quoted in section 3.16, Likelihood of Release: Attribution, of this support 

document, HRS Sections 2.3, Likelihood of release, 4.1.2.1.1, Observed release, and 7.1.1, Observed 

release/observed contamination, require that some portion of the significant increase in hazardous 

substances identified in an observed release be attributable to the site. There is no mention of attribution 

to specific sources. And, as explained in section 3.16, Likelihood of Release: Attribution, of this support 

document and its subsections, the HRS documentation record at proposal adequately provides evidence 

attributing the significant increase in hazardous substances to the Site, consistent with the HRS.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

61 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.16.8 Storm Water Runoff Data

Comment: ARC asserted that storm water runoff data must be collected to adequately identify an 

observed release. ARC specifically questioned the use of source sample JM-SS-03, which was collected 

during drought conditions and was not in contact with surface water, to establish an observed release by 

direct observation in the HRS documentation record at proposal. 

ARC contended that an observed release could not be “quantified,” as storm water runoff data was not 

collected. ARC argued that data must be collected during storm events to “quantify the contribution of 

contaminants from any sources via run-off and direct contact with surface water.” ARC concluded that as 

the surface water sampling event did not comply with HRS protocols, “the Observed Release value in the 

HRS is arbitrary, and must be reassigned.” 

To support this claim, ARC cited Chapter 4 of Sampling Strategies, EPA Guidance for Performing Site 

Inspections Under CERCLA, Interim Final (September 1992). 

ARC further argued that the surface water background samples should have been collected during rain 

events to address contaminants contributed by runoff. ARC stated that: 

background surface water samples were collected during a period of low flow, which 

calls into question the representation of these samples as actual background samples. 

Proper background surface water sampling requires that samples be collected during 

rainfall events to evaluate surface water run-off from natural undisturbed areas of the site. 

To support this assertion, ARC cited the draft HRS Guidance Manual, Interim Final, November 1992, 

Sections 5.1, Consideration for Background and 5.2, Selecting Appropriate Background Samples. 

ARC asserted that surface water background samples used in the HRS documentation record at proposal 

did not reflect site conditions and therefore were inconsistent with HRS criteria. ARC concluded that this 

“mischaracterization” could affect the likelihood of release category factor value of 550 assigned, and that 

further sampling is therefore needed. 

Response: The establishment of an observed release by direct observation was correctly carried out using 

criteria provided in HRS Section 4.1.2.1.1. Although the sample establishing the observed release by 

direct observation (JM-SS-03) was collected during drought, the location would be in contact with the 

waters of the Rio Moquino following rain events. The HRS does not require the collection of samples 

during a storm event to quantify the contribution of contaminants from a source to support the 

establishment of an observed release by direction observation. Furthermore, to the extent that ARC’s 

comment regarding the quantification of contaminants from sources “via runoff” implies that samples of 

runoff itself as it passes over land are required to establish an observed release by direct observation, the 

HRS does not require this. 

On establishing an observed release by direct observation, HRS Section 4.1.2.1.1, Observed release, 

states in relevant part:

Establish an observed release to surface water for a watershed by demonstrating that the 

site has released a hazardous substance to the surface water in the watershed. Base this 

demonstration on either: 
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• Direct observation:

- A material that contains one or more hazardous substances has been seen 

entering surface water through migration or is known to have entered surface 

water through direct deposition, or 

- A source area has been flooded at a time that hazardous substances were 

present, and one or more hazardous substances were in contact with the 

flood waters, or 

- When evidence supports the inference of a release of a material that contains one 

or more hazardous substances by the site to surface water, demonstrated adverse 

effects associated with that release may also be used to establish an observed 

release. . . . [emphasis added] 

Page 33 of the HRS documentation record at proposal states: 

During the March 2010 SI sampling activities, sample JM-SS-03 was collected on the 

bank of the Rio Moquino and close to surface water sample RM-JM-SW (Figure A-5A; 

Ref. 19, pp. 21, 22; Ref. 30, pp. 76, 77). According to Laguna officials, the river banks 

were not reclaimed and source materials are present there (Ref. 19, p. 5). Source sample 

JM-SS-03 was collected during draught conditions and therefore was not in direct contact 

with the surface water. However, after rain events, the Rio Moquino would contain water 

such that sample location JM-SS-03 would be in direct contact with the surface water 

(Ref. 19, pp. 4, 6, 7). Sample JM-SS-03 contained elevated concentrations of total 

uranium at 127 ppm (Ref. 20, pp. 172, 1210; Ref. 26, 1 to 3). The surface water samples 

collected within the Rio Moquino adjacent to this sample contained total uranium at 16.8 

ppb, 109 ppb and 78.9 ppb (Ref. 19, p. 22; Ref. 20, pp. 22, 75, 1190, 1219; Ref. 25, pp. 1 

to 5; Ref. 26, pp 1 to 3; Ref. 35, pp. 96, 772-773, 1587). These concentrations were 

greater than background concentrations found within Rio Moquino (sample RM-SW-BG) 

(Ref. 19, p. 18; Ref. 20, pp. 18, 70, 557, 580,711,782,1203; Ref. 25, pp. 1 to 5, 45 to 49; 

Ref. 26, pp. 1 to 3; Ref. 35, pp. 87-88, 774, 1587). 

Further, Reference 43 of the HRS documentation record at promulgation (a telephone conversation record 

regarding sample location JM-SS-03 and the Rio Moquino) documents that during a recent September 7, 

2011, Rio Moquino flood event, the Source 2 sample location JM-SS-03 was inundated with water. 

Thus, the HRS documentation record at proposal identifies that a source area containing hazardous 

substances is in direct contact with flood waters of the Rio Moquino following rain events, meeting one 

of the HRS-specified methods of establishing an observed release by direct observation. 

Additionally, even if this observed release by direct observation were not established, as further supported 

by sections 3.15 , Likelihood of Release: Background and Significant Increase, and 3.16, Likelihood of 

Release: Attribution, of this support document, an observed release to surface water by chemical analysis 

has been correctly established at the Site, yielding the same likelihood of release factor category value as 

the observed release by direct observation (550). 

Regarding the commenter’s citation of EPA guidance documentation, neither the EPA Guidance for 

Performing Site Inspections Under CERCLA, Interim Final (September 1992) nor the draft HRS 

Guidance Manual, Interim Final, November 1992 (HRS Guidance Manual) impose mandatory 

requirements, and the commenter has not pointed to any specific recommendation in either guidance 

document with which the EPA has been inconsistent. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

63 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.17 Site Watershed/Target Distance Limit 

Comment: In challenging the mine’s effects on surface water, Mr. Parkhill stated that “[t]he Rio San Jose 

runs in a west-to-east direction which is roughly parallel to Interstate I-40. The Jackpile Mine and Paguate 

Mine are located at least 5 to 6 miles north of Rio San Jose, which does not flow in the vicinity of these 

two mines.” 

Response: Regarding Mr. Parkhill’s comment on the distance of the Rio San Jose from the Site, to the 

extent that the commenter is implying that the distance is too great for the Site to have any effect on the 

river, while the HRS documentation record did not identify an observed release in the Rio San Jose, this 

river is within the 15-mile target distance limit (TDL) for the watershed specified by the HRS. Targets 

within this distance limit and in the watershed are therefore correctly considered subject to potential 

contamination by the release from the Site via overland flow.

HRS Section 4.1.1.2, Target distance limit, details the delineation of the TDL, stating that 

[t]he target distance limit defines the maximum distance over which targets are 

considered in evaluating the site. Determine a separate target distance limit for each 

watershed as follows:

. . . 

• If there is an observed release from the site to the surface water in the watershed that 

is based on sampling, begin measuring the target distance limit for the watershed at 

the probable point of entry; extend the target distance limit either for 15 miles along 

the surface water or to the most distant sample point that meets the criteria for an 

observed release to that watershed, whichever is greater.

In evaluating the site, include only surface water targets (for example, intakes, fisheries, 

sensitive environments) that are within or contiguous to the hazardous substance 

migration path and located, partially or wholly, at or between the probable point of entry 

and the target distance limit applicable to the watershed:

. . . 

• Determine whether targets within or contiguous to the hazardous substance 

migration path are subject to actual or potential contamination as follows: 

- If a target is located, partially or wholly, either at or between the probable point 

of entry and any sampling point that meets the criteria for an observed release to 

the watershed or at a point that meets the criteria for an observed release by 

direct observation, evaluate that target as subject to actual contamination, except 

as otherwise specified for fisheries in section 4.1.3.3 and for wetlands in section 

4.1.4.3.1.1. If the actual contamination is based on direct observation, assign 

Level II to the actual contamination. However, if the actual contamination is 

based on samples, determine whether the actual contamination is at Level I or 

Level II concentrations as specified in sections 4.1.2.3, 4.1.3.3, and 4.1.4.3.1. 

- If a target is located, partially or wholly, within the target distance limit for the 

watershed, but not at or between the probable point of entry and any sampling 

point that meets the criteria for an observed release to the watershed, nor at a 

point that meets the criteria for an observed release by direct observation, 

evaluate it as subject to potential contamination.
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64 

Page 32 of the HRS documentation record at proposal describes the Site TDL, which includes a stretch of 

the Rio San Jose: 

The target distance limit (TDL) for the surface water pathway, which defines the 

maximum distance over which targets are considered, is 15 miles. The TDL is defined as 

being 15 miles from the farthest downstream PPE in the in-water segment section. The 

15-mile surface water flow path is presented in Figure A-4 (Ref. 1, Sec. 4.1.1.2). 

Drainage from Source 1 and Source 2 enters the Rio Moquino and Rio Paguate at PPEs 1 

through PPE 4 (refer to Figure A-3). The slope from each source is towards Rio Paguate 

and Rio Moquino (Ref. 3, p. 1). PPE1 is the closest point of entry from the South Paguate 

Pit to Rio Paguate with an overland flow distance of approximately 1,100 feet (Ref. 40, 

pp. 1, 2). PPE2 is the closest point of entry from the North Paguate Pit to Rio Paguate 

with an overland flow distance of approximately 150 feet (Ref. 40, pp. 1, 2). PPE3 is the 

closest point of entry from Waste Dump V to Rio Moquino with a minimal (>0) overland 

flow distance (Ref. 40, pp. 1, 2). PPE4 is the closest point of entry from Jackpile Pit to 

Rio Paguate with an overland flow distance of approximately 840 feet (Ref. 40, pp. 1, 2). 

From PPE1, Rio Paguate flows approximately 1 mile before converging with Rio 

Moquino. From PPE2, Rio Paguate flows approximately 0.7 miles before converging 

with Rio Moquino. From PPE3, Rio Moquino flows approximately 600 feet before 

converging with Rio Paguate. From the convergence, Rio Paguate flows south 

approximately 1 mile before PPE4. From PPE4 Rio Paguate flows approximately 4.2 

miles before entering the Paguate Reservoir and the Mesita Dam. The Paguate Reservoir 

is approximately 0.5 miles long, and then the Rio Paguate continues an additional 0.6 

miles before converging with and becoming the Rio San Jose. The Rio San Jose 

continues for the remaining 15-mile TDL (Ref. 3, pp. 1 to 3; Ref. 12). Within the inwater segment of the TDL, there are two Level II fisheries which have been identified 

between the PPEs and the location where sample PR-SW-01 was collected within the 

northern portion of the Paguate Reservoir (Ref. 23, Figure A-3). There is also a 

potential fishery within the southern portion of the Paguate Reservoir to the Rio 

San Jose downstream to the TDL (Ref. 23, Figure A-3). 

Therefore, the HRS documentation record at proposal12 establishes the 15-mile TDL, the TDL includes a 

portion of the Rio San Jose (as well as portions of the Rio Moquino, Rio Paguate, and Paguate Reservoir), 

and targets within the stretch of the TDL including a portion of the Rio San Jose are eligible to be 

evaluated as subject to potential contamination, consistent with the HRS. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

 

12 Note that, as discussed in section 3.10, Surface Water Pathway Description: Source 1, of this support document,

because Source 1 is no longer evaluated for the overland/flood migration component, probable points of entry 

(PPEs) from Source 1 to surface water described on page 32 of the HRS documentation record at proposal (PPEs 1, 

2, and 4) have been removed from evaluation in the HRS documentation record at promulgation. Only PPE 3 from 

Source 2 remains, and the resulting target distance limit (TDL) has been reduced by approximately 1.1 miles to 

reflect this (as detailed on page 33 and Figure A-5A of the HRS documentation record at promulgation). This 

minimal change has no effects on the targets evaluated, and a portion of the Rio San Jose remains within the TDL at 

promulgation.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

65 

3.18 Human Food Chain Threat: Evidence of Fishing for Consumption 

Comment: ARC challenged the EPA’s estimate of fish consumed as “purely conjecture and hav[ing] no 

basis in fact given the nature of the surface water resource through the Jackpile Mine site.” 

ARC also objected to the following statements included in the EPA’s NPL Site Narrative:

Surface waters of the Rio Paguate and in the Paguate Reservoir contain elevated levels of 

Isotopic Uranium. Fishing has been documented at the reservoir and downstream in the 

Rio San Jose. 

ARC again cited its challenge of the appropriateness of background levels and the establishment of an 

observed release from the Site, in concluding that the EPA should remove language discussing impacts of 

elevated levels of isotopic uranium on fishing in the Reservoir and downstream Rio Paguate. ARC added 

that “[t]he HRS Documentation provides nothing more than anectodal [sic] notes related to assumed fish 

biomass, fishing activity within and downstream from the Jackpile Mine.” 

Response: The HRS documentation record at proposal provides documentation that human consumption 

of fish has been correctly established within the target distance limit and the zone of Level II 

contamination, consistent with HRS procedures. 

As described in section 3.17, Site Watershed/Target Distance Limit, of this support document, the TDL 

includes the Paguate Reservoir and portions of the Rio Moquino, Rio Paguate, and Rio San Jose. 

HRS Section 4.1.3.3, Human food chain threat-targets, explains how to identify a human food chain 

threat target fishery and determine whether it is subject to actual or potential contamination: 

Evaluate two target factors for each watershed: food chain individual and population. 

For both factors, determine whether the target fisheries are subject to actual or potential 

human food chain contamination. 

Consider a fishery (or portion of a fishery) within the target distance limit of the 

watershed to be subject to actual human food chain contamination if any of the 

following apply: 

• A hazardous substance having a bioaccumulation potential factor value of 500 

or greater is present either in an observed release by direct observation to the 

watershed or in a surface water or sediment sample from the watershed at a

level that meets the criteria for an observed release to the watershed from the 

site, and at least a portion of the fishery is within the boundaries of the 

observed release (that is, it is located either at the point of direct observation or 

at or between the probable point of entry and the most distant sampling point 

establishing the observed release).

• The fishery is closed, and a hazardous substance for which the fishery has been 

closed has been documented in an observed release to the watershed from the 

site, and at least a portion of the fishery is within the boundaries of the 

observed release.

• A hazardous substance is present in a tissue sample from an essentially sessile, 

benthic, human food chain organism from the watershed at a level that meets 

the criteria for an observed release to the watershed from the site, and at least a 

portion of the fishery is within the boundaries of the observed release. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

66 

For a fishery that meets any of these three criteria, but that is not wholly within the 

boundaries of the observed release, consider only the portion of the fishery that is 

within the boundaries of the observed release to be subject to actual human food chain 

contamination. Consider the remainder of the fishery within the target distance limit to 

be subject to potential food chain contamination. 

In addition, consider all other fisheries that are partially or wholly within the target 

distance limit for the watershed, including fisheries partially or wholly within the 

boundaries of an observed release for the watershed that do not meet any of the three 

criteria listed above, to be subject to potential human food chain contamination. If only 

a portion of the fishery is within the target distance limit for the watershed, include 

only that portion in evaluating the targets factor category.

HRS Section 4.1.3.3.2.2, Level II concentrations, describes estimating human food production for a 

fishery subject to Level II concentrations:

Determine those fisheries (or portions of fisheries) within the watershed that are subject 

to Level II concentrations. Do not include any fisheries (or portions of fisheries) already 

counted under the Level I concentrations factor. 

Assign each fishery (or portion of a fishery) a value for human food chain population 

from table 4–18, based on the estimated human food production for the fishery. Estimate 

the human food chain production for the fishery as specified in section 4.1.3.3.2.1. 

HRS Section 4.1.3.3.2.3, Potential human food chain contamination, describes estimating human food 

production for a fishery subject to potential contamination: 

Determine those fisheries (or portions of fisheries) within the watershed that are subject 

to potential human food chain contamination. Do not include those fisheries (or portion 

of fisheries) already counted under the Level I or Level II concentrations factors. 

. . . 

• Estimate the human food chain population value (Pi) for a fishery (or portion of a 

fishery) as specified in section 4.1.3.3.2.1. 

HRS Section 4.1.3.3.2.1, Level I concentrations, gives the directions on estimating the human food chain 

population value referred to by HRS Sections 4.1.3.3.2.2, Level II concentrations, and 4.1.3.3.2.3, 

Potential human food chain contamination, quoted above, stating: 

Determine those fisheries (or portions of fisheries) within the watershed that are subject 

to Level I concentrations.

Estimate the human food chain population value for each fishery (or portion of a fishery) 

as follows:

• Estimate human food chain production for the fishery based on the estimated annual 

production (in pounds) of human food chain organisms (for example, fish, shellfish) 

for that fishery, except: if the fishery is closed and a hazardous substance for which 

the fishery has been closed has been documented in an observed release to the fishery 

from a source at the site, use the estimated annual production for the period prior to 

closure of the fishery or use the estimated annual production from comparable 

fisheries that are not closed.
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67 

• Assign the fishery a value for human food chain population from table 4–18, based 

on the estimated human food production for the fishery.

• Set boundaries between fisheries at those points where human food chain production 

changes or where the surface water dilution weight changes.

Page 50 of the HRS documentation record at proposal presents the rationale for identifying a human food 

chain fishery associated with the Site, and identifies that surface water observed release samples 

contained a hazardous substance with a bioaccumulation factor value greater than or equal to 500. It 

states:

Level II concentrations in the surface water pathway can be established based on surface 

water samples that meet the criteria for an observed release and the hazardous substance 

has a bioaccumulation potential factor value greater or equal to 500 (Ref. 1, Sec. 4.1.3.3). 

As noted in Sections 4.1.2.1.1 and 4.1.3.2.1 of this HRS documentation record, an 

observed release of hazardous substances having a bioaccumulation factor value of 500 

or greater (uranium238 and manganese) is documented in Rio Paguate. A human food 

chain fishery is present in Rio Paguate within the TDL (Ref. 3, pp. 2, 3; Ref. 23; Figure 

A-3). According to the Pueblo of Laguna Environmental and Natural Resources 

Department, Rio Paguate and Rio San Jose are fished for catfish, bluegill, and crappie 

that are caught for human consumption (Ref. 23). Level II concentrations of manganese, 

uranium234, uranium235, and uranium238 in surface water samples have been documented 

within the surface water flow path from samples RM-JM-SW and RP-JM-SW to a 

distance of 27,800 feet downstream (Ref. 12). The area beginning from the farthest 

downstream Level II sample location (PR-SW-01) to the 15-mile TDL is subject to 

potential contamination (refer to Figure A-3). 

Reference 23 cited in the text above is a March 2010 memorandum from Curtis Francisco, Water Quality 

Specialist of the Pueblo of Laguna Environmental and Natural Resources Department, on fishing in the 

Rio Paguate and Rio San Jose. The memorandum states that “fishing does occur on the Rio Paguate and 

Rio San Jose,” providing the following description:

The segments of the Rio Paguate below the mine and in the area of the Paguate Reservoir 

AKA Mesita Dam are also used by locals to catch catfish, bluegill and what I believe to 

be crappie because of the symbiotic relationship with wading birds such as herons where 

the fishes eggs stick to the legs of the birds and are dropped off in new bodies of water 

and the fish populate them. The Rio San Jose is also fished but for the same species of 

fish that are found in the lower reaches of the Rio Paguate. . . . Fishing in the Rio Paguate 

below the mine is discouraged as is in the Rio San Jose however, residents still fish and 

consume the fish caught there, evidence has been observed numerous times on the Rio 

Paguate at and around the Mesita Dam and at the Village of Mesita at the Rio San Jose 

Irrigation Diversion which is below the convergence with the Rio Paguate. 

Thus, the HRS documentation record at proposal correctly identifies a fishery in the Rio Paguate and Rio 

San Jose within the TDL. 

Page 53 of the HRS documentation record at proposal identifies that a fishery exists within the zone of 

actual contamination, subject to Level II contamination, and provides a rationale for assigning a human 

food chain production of greater than zero pounds per year: 
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68 

The zone of Level II contamination in Rio Paguate extends 27,800 feet from samples 

RM-JM-SW/SED and RP-JM-SW/SED13 to the farthest downstream sample location, 

PR-SW/SED-01 (Section 4.1.2.1.1). Rio Paguate and the Paguate Reservoir (Mesita 

Dam) are fished for catfish, bluegill, and crappie according to the Pueblo of Laguna 

Environmental and Natural Resources Department, and these fish are caught for 

human consumption (Ref. 23, p. 1; Ref. 40, p. 1). Data to estimate pounds of fish caught 

annually for Rio Paguate and Paguate Reservoir are not available; however, because 

these water bodies are fished, the annual production is known to be greater than zero. 

[emphasis added]

This value of greater than zero pounds per year was then used to assign a human food chain population 

value of 0.03, consistent with HRS Table 4-18, Human Food Chain Population Values, which prescribes 

this value for a human food chain production falling in the category of “Greater than 0 to 100” pounds per 

year.

Similarly, page 54 of the HRS documentation record at proposal describes the portion of the fishery 

within the TDL but downstream of the zone of actual contamination subject to potential contamination: 

Rio San Jose and the southern portion of the Paguate Reservoir are fished for catfish, 

bluegill, and crappie according to the Pueblo of Laguna Environmental and Natural 

Resources Department; these fish are caught for human consumption (Ref. 23; Ref. 

41). Data to estimate pounds of fish caught annually for Rio San Jose and Paguate 

Reservoir are not available; however, because this water body is fished, the annual 

production is known to be greater than zero. As such, a human food chain population 

value of 0.03 is assigned from Table 4-18 of the HRS (Ref. 1, Table 4-18). [emphasis 

added] 

Again, as there is documented fishing, but a production value was not available, a human food chain 

production of greater than zero pounds per year was assigned (and compared to the same range of 

production values in HRS Table 4-18), consistent with the HRS. Reference 41 cited in the above text 

provides additional documentation of fishing in a statement from Frank A. Ortiz Cerno, Natural 

Resources Specialist for Pueblo of Laguna Environmental and Natural Resources Department; this 

statement summarizes a conversation with village of Mesita tribal member Stacey Carr, in which Mr. Carr 

noted that he and his girlfriend consumed fish from the waters just downstream of Mesita Dam.

Therefore, the HRS documentation record at proposal correctly identifies a portion of a fishery subject to 

actual contamination and a portion of a fishery subject to potential contamination, and correctly 

determines a human food chain production of greater than zero pounds per year for each, consistent with 

the HRS. ARC raised no specific issues regarding the information in HRS package References 23, 40 and 

41. 

 

13 As explained in section 3.10, Surface Water Pathway Description: Source 1, of this support document, as Source 1 

is no longer evaluated for the overland/flood migration component, the release samples RP-JM-SW and RP-JM-SW110420 (in the Rio Paguate, upstream of the rivers’ confluence) are also no longer considered in the evaluation of 

the overland/flood migration component. The removal of these samples from evaluation as evidence of an observed 

release for the overland/flood migration component means that the segment of Rio Paguate from that sample to the 

confluence of the rivers is no longer considered part of the zone of actual contamination for the overland/flood 

migration component. This change results in no effects on the Level II fishery scored, since, as noted above, the 

fishery is located below the mine and in the area of the Paguate Reservoir (downstream of the confluence).
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

69 

To the extent that ARC’s comment regarding the EPA estimate of fish consumed as “purely conjecture” 

due to the “nature of the surface water resource through the Jackpile Mile site” questions the presence of 

fish within the boundaries of the mine property, the HRS only requires that a qualifying fishery be 

documented within the target distance limit to be scored. As detailed in the HRS documentation record at 

proposal, the fishery evaluated extends from below the mine property boundary.

Furthermore, as the documentation of fishing for human consumption has been appropriately established 

within the target distance limit and zone of actual contamination, consistent with procedures set forth in 

the HRS, it is appropriate to discuss in the NPL Site Narrative the potential impacts from the observed 

release of hazardous substances on downstream fishing use. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.19 Human Food Chain Threat: Use of Bioaccumulation Value 

Comment: ARC questioned the use of a bioaccumulation value without supporting fish tissue data. 

ARC questioned the use by the EPA of a “bioaccumulation pathway” to evaluate the risk posed to human 

health, due to a Level I concentrations factor value of 0 being assigned in the HRS documentation record 

at proposal. ARC commented that because of the lack of human health targets scored in the “drinking 

water pathway,” that the EPA relied on evaluating the “less direct bioaccumulation pathway for fish, 

cattle and elk.” ARC contended that the “scoring of the bioaccumulation pathway” is based on 

assumptions that “uranium and manganese uptake in fish, cattle, and elk would pose a risk to human 

health;” However, no tissue sampling data is provided to support this risk; therefore, the “EPA’s 

assertions are arbitrary and capricious,” and the human food chain threat score “must be reevaluated to 

eliminate these assigned values.” 

Response: The human food chain threat score assigned in the HRS documentation record at proposal was 

calculated correctly using the HRS, including the use of a bioaccumulation factor value. The HRS does 

not require the use of analytical data from fish tissue to document human food chain fishery targets 

subject to actual contamination (i.e., Level II contamination levels) or potential contamination, or to 

support the use of bioaccumulation potential factor values. Regarding the evaluation of cattle and elk in 

the HRS documentation record at proposal, the associated resources factor value was generated as part of 

the drinking water threat evaluation and not the human food chain threat; this evaluation of eligible 

resources does not consider the bioaccumulation of hazardous substances. Finally, the HRS does not 

include a “bioaccumulation pathway.” These points are detailed in the following subsections: 

• HRS Requirements 

o Calculation of Human Food Chain Threat Waste Characteristics Factor Category Value

o Determination of Targets Subject to Actual Contamination

o Evaluation of the Resources Factor Value

• HRS Documentation Record Evaluation 

• Summary

HRS Requirements

The HRS assigns a bioaccumulation potential factor value to eligible hazardous substances for two 

purposes in the surface water migration pathway overland flow/flood migration component human food 
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70 

chain threat: (1) calculation of a waste characteristics factor category value and (2) determination of 

whether a fishery within a target distance limit is subject to actual human food chain contamination. 

Separately, within the drinking water threat of the surface water migration pathway overland flow/flood 

migration component, a resources factor value is assigned (and does not involve a bioaccumulation 

potential factor value).

Calculation of Human Food Chain Threat Waste Characteristics Factor Category Value 

HRS Section 4.1.3.2, Human food chain threat-waste characteristics, states to “[e]valuate the waste 

characteristics factor category for each watershed based on two factors: toxicity/persistence/ 

bioaccumulation and hazardous waste quantity.” 

HRS Section 4.1.3.2.1.4, Calculation of toxicity/persistence/bioaccumulation factor value, states how the 

bioaccumulation potential factor value is used to determine the toxicity/persistence/bioaccumulation 

factor value for a hazardous substance: 

Assign each hazardous substance a toxicity/persistence factor value from Table 4-12, 

based on the values assigned to the hazardous substance for the toxicity and persistence 

factors. Then assign each hazardous substance a toxicity/persistence/bioaccumulation 

factor value from Table 4-16, based on the values assigned for the toxicity/persistence 

and bioaccumulation potential factors. Use the hazardous substance with the highest 

toxicity/persistence/bioaccumulation factor value for the watershed to assign the value to 

this factor. Enter this value in Table 4-1. 

HRS Section 4.1.3.2.3, Calculation of human food chain threat-waste characteristics factor category 

value, describes how a bioaccumulation potential factor value is used to calculate a human food chain 

threat-waste characteristics factor category for the watershed: 

For the hazardous substance selected for the watershed in section 4.1.3.2.1.4, use its 

toxicity/persistence factor value and bioaccumulation potential factor value as follows to 

assign a value to the waste characteristics factor category. First, multiply the 

toxicity/persistence factor value and the hazardous waste quantity factor value for the 

watershed, subject to a maximum product of 1x108

. Then multiply this product by the 

bioaccumulation potential factor value for this hazardous substance, subject to a 

maximum product of 1x1012. Based on this second product, assign a value from Table 2-7 

(section 2.4.3.1) to the human food chain threat-waste characteristics factor category for 

the watershed. Enter this value in Table 4-1. 

Determination of Targets Subject to Actual Contamination 

HRS Section 4.1.3.3, Human food chain threat-targets, describes the use of the bioaccumulation potential 

factor value in establishing that a fishery located within a target distance limit is subject to actual 

contamination: 

Evaluate two target factors for each watershed: food chain individual and population. For 

both factors, determine whether the target fisheries are subject to actual or potential 

human food chain contamination. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

71 

Consider a fishery (or portion of a fishery) within the target distance limit of the 

watershed to be subject to actual human food chain contamination if any of the following 

apply: 

• A hazardous substance having a bioaccumulation potential factor value of 500 or 

greater is present either in an observed release by direct observation to the watershed 

or in a surface water or sediment sample from the watershed at a level that meets the 

criteria for an observed release to the watershed from the site, and at least a portion of 

the fishery is within the boundaries of the observed release (that is, it is located either 

at the point of direct observation or at or between the probable point of entry and the 

most distant sampling point establishing the observed release). 

Evaluation of the Resources Factor Value 

HRS Section 4.1.2.3.3, Resources, identifies the eligibility criteria and evaluation process to determine a 

resources factor value (and does not include use of a bioaccumulation potential factor value): 

To evaluate the resources factor for the watershed, select the highest value below that 

applies to the watershed. Assign this value as the resources factor value for the 

watershed. Enter this value in Table 4–1. 

Assign a value of 5 if, within the in-water segment of the hazardous substance migration 

path for the watershed, the surface water is used for one or more of the following 

purposes: 

• Irrigation (5 acre minimum) of commercial food crops or commercial forage 

crops. 

• Watering of commercial livestock.

• Ingredient in commercial food preparation. 

• Major or designated water recreation area, excluding drinking water use.

HRS Documentation Record Evaluation 

Page 48 of the HRS documentation record at proposal presents toxicity/persistence/bioaccumulation 

factor value data for eligible hazardous substances. Page 49 of the HRS documentation record at proposal 

describes the process used to calculate the waste characteristics factor category value for the human food 

chain threat using a bioaccumulation potential factor value from the hazardous substance with the highest 

toxicity/persistence/bioaccumulation factor value14: 

Toxicity/Persistence Factor Value: 10,000 

Hazardous Waste Quantity Factor Value: 1,000,000 

Bioaccumulation Potential Factor Value: 50,000 

10,000 (Toxicity/Persistence Factor Value) x 1,000,000 (Hazardous Waste Quantity 

Factor Value) = 1 x 1010 (maximum of 1 x 108

 according to HRS Section 4.1.3.2.3) 

1 x 108 (Toxicity/Persistence Factor Value x Hazardous Waste Quantity Factor Value) x 

 

14 As detailed in section 3.25.2, Human Food Chain Threat Waste Characteristics, of this support document, waste 

characteristics calculations have been updated in the HRS documentation record at promulgation based on Source 1 

removal from the evaluation of the surface water pathway overland/flood migration component (and removal of 

Source 1-specific hazardous substances from scoring).
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72 

50,000 (Bioaccumulation Potential Factor Value) = 5 x 1012 (maximum of 1 x 1012

according to HRS Section 4.1.3.2.3) 

A hazardous waste quantity factor of 1,000,000 is assigned according to HRS Section 

2.4.2.2. From Reference 2 and Table 4-12 of the HRS, manganese and uranium238 have a 

toxicity/persistence value of 10,000 and a bioaccumulation potential factor of 50,00015. 

The waste characteristics factor category value from Reference 1, Table 2-7 for a waste 

characteristics product of 1 x 1012 is 1,000. 

Hazardous Waste Quantity Assigned Value: 1,000,000 

Waste Characteristics Factor Category Value: 1,000

Thus, the HRS documentation record at proposal uses a bioaccumulation potential factor value in 

determining a human food chain threat waste characteristics factor category value, according to HRS 

requirements.

As explained in section 3.18, Human Food Chain Threat: Evidence of Fishing for Consumption, of this 

support document, the human consumption of fish has been correctly established within the target 

distance limit and the zone of contamination at the Site. Page 50 of the HRS documentation record at 

proposal documents that a fishery located within the target distance limit is subject to actual human food 

chain contamination based on the presence of an eligible hazardous substance with a bioaccumulation 

potential factor value of 500 or greater:

Level II concentrations in the surface water pathway can be established based on surface 

water samples that meet the criteria for an observed release and the hazardous substance 

has a bioaccumulation potential factor value greater or equal to 500 (Ref. 1, Sec. 4.1.3.3). 

As noted in Sections 4.1.2.1.1 and 4.1.3.2.1 of this HRS documentation record, an 

observed release of hazardous substances having a bioaccumulation factor value of 500 

or greater (uranium238 and manganese) is documented in Rio Paguate. A human food 

chain fishery is present in Rio Paguate within the TDL (Ref. 3, pp. 2, 3; Ref. 23; Figure 

A-3). According to the Pueblo of Laguna Environmental and Natural Resources 

Department, Rio Paguate and Rio San Jose are fished for catfish, bluegill, and crappie 

that are caught for human consumption (Ref. 23). Level II concentrations of manganese, 

uranium234, uranium235, and uranium238 in surface water samples have been documented 

within the surface water flow path from samples RM-JM-SW and RP-JM-SW to a 

distance of 27,800 feet downstream (Ref. 12). 

Therefore, the HRS documentation record at proposal uses the bioaccumulation potential factor value in

identifying the presence of a fishery within the target distance limit subject to actual human food chain 

contamination (i.e., Level II contamination levels), consistent with the HRS.

Page 48 of the HRS documentation record at proposal provides the rationale for assigning a resources 

factor value of 5 to the Site:

The Rio Paguate is designated by the New Mexico Water Quality Control Commission 

for the following uses: domestic water supply, fish, culture, high-quality coldwater 

 

15 Note that this sentence incorrectly states that uranium-238 has a bioaccumulation potential factor value of 50,000 

(the correct value at the time of proposal, 5,000, was shown in the table on page 48 of the HRS documentation 

record at proposal). The related sentence has been corrected in the HRS documentation record at promulgation. The 

bioaccumulation potential factor value for manganese of 50,000 was correctly assigned.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

73 

fishery, irrigation, livestock, and wildlife watering, and secondary contact recreation 

(Ref. 4, p. 106). According to Laguna Natural Resource officials, there are approximately 

1,500 cattle whose only source of drinking water is the surface water from the Rio 

Paguate and the Paguate Reservoir within the TDL. These cattle are used for meat by the 

tribe. There are also approximately 800 cow elk that use the surface water for drinking 

(Ref. 4, pp. 98, 100, 104; Ref. 19, pp. 6, 7). As such, under the HRS, a resources value of 

5 is assigned to the surface water, in-water segment of the hazardous substance migration 

path for the watershed used for watering of commercial livestock (Ref. 1, Section 

4.1.2.3.3). 

Resources Factor Value: 5

Thus, the HRS documentation record at proposal correctly identifies and scores the presence of a resource 

eligible for evaluation. This evaluation did not involve the consideration of a bioaccumulation potential 

factor value (and was performed under the drinking water threat of the surface water pathway, not the 

human food chain threat). 

Summary

In summary, the HRS documentation record at proposal correctly identifies and applies bioaccumulation 

potential factor values in determining the waste characteristics factor category value and for identifying 

the presence of a fishery subject to actual human food chain contamination; the Human Food Chain 

Threat score was correctly calculated. Further, analytical data from tissue samples (e.g., from fish) are not 

required by the HRS to support the documentation that human food chain targets are subject to actual 

contamination16, or to support the use of bioaccumulation potential factor values. 

Lastly, the HRS does not include a “bioaccumulation pathway” as one of the pathways through which 

targets may be exposed to hazardous substances. HRS Section 2.1, Overview, summarizes the structure of 

the HRS, and lists the four HRS pathways: ground water migration, surface water migration, soil 

exposure, and air migration. 

These comments result in no change to the HRS score and no change to the decision to place the Site on 

the NPL. 

3.20 Human Food Chain Threat: Toxicity/Persistence/Bioaccumulation 

Comment: ARC asserted there is an error in the calculation of one of the human food chain threat 

toxicity/persistence/bioaccumulation factor values. 

ARC stated that “there may be an error in calculation of the combined toxicity/persistence/ 

bioaccumulation factor value” presented in the table on page 48 of the HRS documentation record at 

proposal. Referring to rows in that table, ARC noted that one set of procedures for calculating this factor 

value was used for rows 1 through 5, a second set for rows 6 through 12 and a third version for row 13. 

ARC concluded by stating that one of the two factor values of 5x108

 is incorrect and that this error 

detracts from overall confidence in all calculations in the HRS. 

 

16 Note that the HRS does allow as an option the use of tissue analytical results in documenting a surface water 

observed release (HRS Section 4.1.2.1.1, Observed release) and in establishing human food chain Level I 

contamination (HRS Section 4.1.3.3, Human food chain threat-targets).
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74 

Response: Based on this comment, the human food chain threat toxicity/persistence/bioaccumulation 

factor values provided for the hazardous substances have been recalculated and the errors referred to by 

the commenter have been corrected in the HRS documentation record at promulgation using the specified 

HRS approach. This revision itself results in no change in selection of the 

toxicity/persistence/bioaccumulation factor value used in calculating the waste characteristics factor 

category value. However, as described in section 3.10, Surface Water Pathway Description: Source 1, of 

this support document, Source 1 is no longer included in the evaluation of the overland/flood migration 

component of the surface water pathway in the HRS documentation record at promulgation; therefore, the 

Source 1 source hazardous waste quantity value and hazardous substances (including radium) available to 

migrate from Source 1 to surface water via the overland/flood component are no longer considered in the 

calculation of the waste characteristics factor category values. Section 3.25, Waste Characteristics, of this 

support document, and its subsections show that the removal of the Source 1 waste quantity from the 

overland/flood migration component evaluation results in no change to waste characteristics factor 

category values, and no change to the Site score.

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.21 Ground Water to Surface Water Migration Component: Background 

Comment: ARC challenged the applicability of ground water to surface water migration component 

ground water background samples, asserting they are not representative of background conditions for 

Jackpile Mine ground water based on uranium isotope ratios. 

ARC asserted that the ratio of U-234/U-238 in ground water background samples (0.4 to 8.64) is different 

than the ratio in contaminated ground water characterization samples (1.10 to 1.18) presented in the HRS 

documentation record at proposal. ARC concluded that this difference indicates that “the source of 

uranium in background groundwater is not the same as mine site groundwater,” and therefore “the wells 

selected to represent background conditions for uranium concentrations in groundwater were not 

representative of background conditions for Jackpile Mine groundwater.” In reference to this comment 

ARC also stated that “[b]ackground surface water and groundwater sampling, sufficient to meet the 

substantive requirements of the HRS, must be conducted before a HRS that meets the requirements of 

CERCLA and the NCP can be prepared.” 

Response: The ground water to surface water migration component of the surface water migration 

pathway was not evaluated for HRS scoring purposes; the information provided on this component in the 

HRS documentation record at proposal was included to notify the public that this component may be of 

concern to the EPA and may be evaluated during further investigations. However, the background 

samples presented would be sufficient for use in establishing observed release background levels if this 

component were included in the scoring, in a manner consistent with the HRS and its use as a screening 

tool. To the extent feasible, these background samples account for uranium contributed to ground water 

by natural sources. 

Furthermore, as pointed out in the ESI Revised Conceptual Site Model included in Reference 35 of the 

HRS documentation record at proposal, the U-234/U-238 ratio differences referred to by the commenter 

actually support that the contamination found in ground water observed release samples is coming from 

materials generated by the mining processes at the Site and the change in the chemical and physical 

nature of the ore due to these processes, and that uranium levels in the ground water background samples 

represent naturally occurring uranium concentrations in the absence of those processes. That is, the 

isotopic ratios in the ground water background samples represent the combined sources of uranium in the 

watershed/source waters upgradient of the Site, whereas the isotopic ratios in the observed release ground 
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water samples likely predominantly reflect the uranium from the Jackpile Sandstone (and its isotopic 

signature) in waste materials that has been disturbed by mining processes and made mobile and available 

to ground water at and downgradient of the mine. 

These points are detailed in the following subsections:

• HRS Ground Water Background Sample Requirements 

• HRS Documentation Record Evaluation 

• HRS Documentation Record Reference 35 Conceptual Site Model Assessments

HRS Ground Water Background Sample Requirements

The HRS does not provide instructions or considerations for establishing background levels beyond 

requiring that samples from one medium be compared to samples from the same type of sample. For the 

ground water to surface water migration component, HRS Section 4.2.2.1.1, Observed release, specifies 

“[e]stablish an observed release to the uppermost aquifer as specified in section 3.1.1.” HRS Section 

3.1.1, Observed release, states: 

Establish an observed release to an aquifer by demonstrating that the site has released a 

hazardous substance to the aquifer. Base this demonstration on either: 

. . . 

• Chemical analysis – an analysis of ground water samples from the aquifer indicates 

that the concentration of hazardous substance(s) has increased significantly above the 

background concentration for the site (see section 2.3). Some portion of the 

significant increase must be attributable to the site to establish the observed release, 

except: when the source itself consists of a ground water plume with no identified 

source, no separate attribution is required. 

HRS Section 2.3, Likelihood of release, states, in part: 

Establish an observed release either by direct observation of the release of a hazardous 

substance into the media being evaluated (for example, surface water) or by chemical 

analysis of samples appropriate to the pathway being evaluated (see sections 3, 4, and 

6). The minimum standard to establish an observed release by chemical analysis is 

analytical evidence of a hazardous substance in the media significantly above the 

background level. Further, some portion of the release must be attributable to the site. 

Use the criteria in Table 2–3 as the standard for determining analytical significance.

Specific to identifying an observed release of radionuclides, HRS Section 7.1.1, Observed 

release/observed contamination, states:

For radioactive substances, establish an observed release for each migration pathway by 

demonstrating that the site has released a radioactive substance to the pathway (or 

watershed or aquifer, as appropriate); establish observed contamination for the soil 

exposure pathway as indicated below. Base these demonstrations on one or more of the 

following, as appropriate to the pathway being evaluated: 

. . . 

Analysis of radionuclide concentrations in samples appropriate to the pathway (that is, 

ground water, soil, air, surface water, benthic, or sediment samples):
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-For radionuclides that occur naturally and for radionuclides that are ubiquitous in the 

environment: 

--Measured concentration (in units of activity, for example, pCi per kilogram 

[pCi/kg], pCi per liter [pCi/1], pCi per cubic meter [pCi/m3 ]) of a given 

radionuclide in the sample are at a level that:

---Equals or exceeds a value 2 standard deviations above the mean sitespecific background concentration for that radionuclide in that type 

of sample, or 

---Exceeds the upper-limit value of the range of regional background 

concentration values for that specific radionuclide in that type of sample.

--Some portion of the increase must be attributable to the site to establish the 

observed release (or observed contamination), and

--For the soil exposure pathway only, the radionuclide must also be present at the 

surface or covered by 2 feet or less of cover material (for example,

soil) to establish observed contamination. [emphasis added] 

In effect, background samples are primarily used to establish background levels for the purpose of 

identifying a significant increase in hazardous substance concentrations; they may secondarily be used to 

assist in attributing some portion of that significant increase to a site.

HRS Documentation Record Evaluation 

Page 55 of the HRS documentation record at proposal states that “[h]ydrologic data indicate that both 

surface water and ground water flow from east-northeast to west-southwest in the western half of the 

study area, and from north to south in the eastern half of the study area.” Figure A-5B of the HRS 

documentation record at proposal shows the locations of the background sample wells, generally 

upgradient or sidegradient of the Site. Page 57 of the HRS documentation record at proposal shows that 

background and release ground water samples were collected during the same 3-day time frame, using the 

same collection techniques, and analyzed using the same methodology.

Page 55 of the HRS documentation record at proposal also states: 

• Uranium concentrations/activities increase with respect to background in both ground 

water and surface water across the facility. This is demonstrated in the results of the 

2011 ESI sampling event, as well as at least four studies involving surface water, and 

two studies involving ground water ( (Ref. 35, p. 2794). 

• Ground water, surface water, and sediment samples collected on-site and 

downgradient of the facility have uranium activities that are significantly elevated 

with respect to background above the property (Ref. 35, p. 2783). 

HRS Documentation Record Reference 35 Conceptual Site Model Assessments

The ESI Revised Conceptual Site Model included in Reference 35 of the HRS documentation record 

provides further evidence that ground water background samples presented in the HRS documentation 

record at proposal are appropriate for identifying ground water background uranium levels. The model 

describes how uranium has been mobilized by effects of the mining processes – via oxygenated waters 

and the increased available surface area of crushed ore/waste; it also explains that this increased uranium 

mobility is not naturally present in the undisturbed Jackpile Sandstone/Jackpile aquifer. This increased 

mobility of uranium at the mine explains why observed release ground water samples have uranium 

isotope ratios (likely representative of Jackpile Sandstone, disturbed by mining ) different from those in 
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background ground water samples (whose ratios may be more representative of other upgradient 

formations).

Page 2748 of Reference 35 (section 4.4.1 of the ESI Revised Conceptual Site Model) notes that 

“[o]xidation/reduction reactions between pore waters and the bedrock are the primary mechanism

for mobilization and deposition of uranium-bearing minerals in the host rock.” 

Page 2790 of Reference 35 (section 4.4.1 of the ESI Revised Conceptual Site Model) identifies that 

oxidation in pit waters is mobilizing uranium that may then enter the ground water-surface water system:

Oxidation reactions between water and waste rock are occurring in the backfilled pits. 

This is evident not only from direct oxygen and ORP measurements of the pit waters, but 

from water analyses that show uranium activities that are four orders of magnitude higher 

than background concentrations in surface water and groundwater above the site. 

Dissolved oxygen measurements in the pit waters are among the highest recorded at the 

site, indicating that the pit waters are communicating with atmospheric oxygen. . . . The 

hydrologic connectivity between the pits and the surface water – groundwater system 

indicates that contaminants in the pits can migrate into the surface water system. . . . 

Contamination appears to be leached from the mine waste materials that have been piled 

along the river systems, used to replace the natural alluvium in places where the river was 

diverted for the sake of mining, and backfilled into the three main mining pits at the site. 

Leaching of uranium oxides in the mine wastes is facilitated by the saturation with 

oxygenated water and the increased surface area of the mineral material due to blasting, 

crushing, and milling. Contaminants migrate in the dissolved load of groundwater, and 

they may be dissolved and re-deposited several times due to the high evaporation rates in 

the vadose zone and in the subaerial environment.

Page 2786 of Reference 35 (section 4.4.1 of the ESI Revised Conceptual Site Model) describes 

differences in dissolved oxygen and oxidation-reduction potential (ORP) in ground water background vs. 

observed release samples:

Dissolved oxygen in the three background wells installed in the Jackpile Sandstone 

(MWs 1, 7, and 8) are the lowest in the study group, ranging from 2.9 to 5.6 ppm; ORP 

values in these wells range from 71 to 133.6 mV. Dissolved oxygen in the background 

well, MW-RM, is measured at 10.8 ppm, and ORP at this well is measured at 111 mV. 

The dissolved oxygen range measured in the on-site and down-gradient wells is between 

8.1 and 12.8 ppm, and the ORP range is between -23.5 and 115.8 mV. The dissolved 

oxygen range measured in the pit wells is between 7.7 and 12.0 ppm, and the ORP values 

range between 45.4 and 117.3. 

Page 2788 of Reference 35 (section 4.4.1 of the ESI Revised Conceptual Site Model) further describes the 

effect of oxidation on uranium mobility:

oxidation state plays a critical role in uranium mobility in the hydrologic system. Preremedial contaminant modeling conducted by Dames and Moore (1983) relied on the 

assumption that conditions in the pits would stabilize in the anoxic range within a few 

years so that uranium oxides would stay in the pits. The dissolved oxygen concentrations 

in the pit waters, not to mention uranium activities four orders of magnitude higher than 

background, indicate that oxidation reactions are occurring in the pit waters. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

78 

Oxidation reactions are also likely occurring where groundwater flows through the 300+ 

million tons of waste rock re-deposited at the site that are not in the backfilled pits. Much 

of this material is mapped as being piled along the sides of the pits and Rios Paguate and 

Moquino; however, there is evidence that the rivers were routinely diverted during 

mining activities. As a result, much of the original alluvium through the site was 

excavated in an effort to access the Jackpile Sandstone, and replaced with waste rock 

(Contact Report #1). This means that the Alluvial Aquifer at the site is flowing through a 

host material that is at least partially, if not entirely, Jackpile-Paguate waste rock.

Page 2791 of Reference 35 (section 4.4.1 of the ESI Revised Conceptual Site Model) states: 

Based on historical groundwater sampling data, Jackpile groundwater is an unlikely 

source of natural uranium contamination. Groundwater monitoring wells located upgradient of the site, and screened in the Jackpile Aquifer, consistently yield low uranium 

concentrations and/or activities with respect to down-gradient surface water and 

groundwater sampling locations (see Table 4 and associated references therein). Field 

measurements taken during the 2011 ESI indicate that three background wells installed in 

the Jackpile Aquifer have the lowest dissolved oxygen concentrations of the entire data 

set. In addition, uranium oxide deposition is known to be intimately associated with 

concentrations of organic material, especially in the upper portions of the Jackpile 

Sandstone (Owen, et al., 1984); this organic material may provide additional protection 

of uranium oxides in the undisturbed form. Regardless, uranium oxides do not appear to 

be significantly mobile in the Jackpile Aquifer above the site.

Thus, possibly due to the lower dissolved oxygen levels in upgradient Jackpile Aquifer background 

samples, organic material in the Jackpile Sandstone, and the intact nature of upgradient Jackpile 

Sandstone, uranium is less naturally mobile in the Jackpile Aquifer near background locations compared 

to the pits and other disturbed areas.

Therefore, the isotopic ratios in the ground water background samples represent the combined sources of 

uranium in the watershed/source waters upgradient of the Site, which is probably derived from 

Cretaceous-Tertiary rocks through which these waters flow, whereas the isotopic ratios in the observed 

release ground water samples likely predominantly reflect the uranium from the Jackpile Sandstone (and 

its isotopic signature) in waste materials that has been disturbed by mining processes and made mobile 

and available to ground water at and downgradient of the mine. The change in isotopic ratio in the release 

samples is a strong indicator of mixing with a water population with a different isotopic signature at 

concentrations substantial enough (relative to those in backgrounds) to exert significant changes in the 

isotopic ratios. Therefore, the shift in uranium isotope ratios referred to by the commenter is further 

evidence attributing uranium releases to mining operations, and does not invalidate the ground water 

background samples. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.22 Ground Water to Surface Water Migration Component: Presence of 

Water in Pits 

Comment: Mr. Parkhill commented that during a visit to the Site in 1981 he observed that the mine was 

dry, asserting that “[t]he lack of any standing water means that the Jackpile Mine is completely above the 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

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water table and could not have been the source of Uranium or any other metals that were leached out of 

the rock to become contaminants of the surface or groundwater.” 

Response: The HRS documentation record at proposal clearly identifies that since the end of mining 

activities, ground water levels in the pits have rebounded. And, inasmuch as the commenter’s assertion 

that the mine is above the water table affects the ground water to surface water migration component of 

the surface water pathway (which was presented in the HRS documentation record at proposal but not 

evaluated for scoring purposes), there is no HRS requirement that a source be in direct contact with 

ground water to be considered for this component. 

HRS Section 4.2.2.2, Drinking water threat-waste characteristics, contains instruction on evaluating the 

waste characteristics factor category value. In this evaluation, it states to consider “only those hazardous 

substances available to migrate from the sources at the site to the uppermost aquifer (see section 3.2),” 

and that 

[s]uch hazardous substances include:

• Hazardous substances that meet the criteria for an observed release to ground water. 

• All hazardous substances associated with a source that has a ground water containment 

factor value greater than 0 (see sections 2.2.2, 2.2.3, and 3.1.2.1). 

HRS Section 3.1.2.1, Containment, describes various containment measures applicable to sources 

evaluated for their containment to ground water (including assessment of the presence of elements such as 

liners, maintained engineered covers, run-on control systems, run-off management systems). If no liner is 

present, a source receives a containment value of 10 (indicating that hazardous substances are not 

contained from migration to ground water). As ground water has infiltrated the pits, were the ground 

water to surface water migration component scored, the hazardous substances in the pit waste would 

clearly be available to migrate from the source.

Pages 55-56 of the HRS documentation record at proposal indicates that since the end of mining 

activities, ground water levels in the pits have rebounded in several places:

Mining activities have historically lowered ground water elevations in the upgradient 

areas of the facility, but not the downgradient areas. The cessation of mining activities, 

as well as the backfilling of the Paguate and Jackpile pits, has caused the ground 

water system to rebound. This rebound was predicted before the pits were 

backfilled; however, the rate of ground water rebound appears to be faster for the 

South Paguate Pit than anticipated. The models predict that ground water 

accumulating in the pits will flow through the natural (Jackpile and Alluvium) geologic 

materials, as well as waste rock and tailings, to flow into the surface water system (Ref. 

25, p. 2773). 

Geologic cross sections completed through the facility indicate that surface water may 

have flowed into the North and South Paguate pits, causing ground water to 

rebound more quickly than modeled. Ground water elevations indicate that ground 

water from the North Paguate and Jackpile pits is flowing into Rio Moquino. Ground 

water from the South Paguate Pit appears to be flowing into Rio Paguate, and water from 

Rio Paguate (and/or the associated Alluvial Aquifer) may be flowing into the North 

Paguate Pit (Ref. 35, pp. 2767, 2773). 

Historical hydrologic data establish that there is hydrologic communication between 

surface water and both natural ground water reservoirs (Alluvial and Jackpile) at the 
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facility. This observation is based on ground water and surface water elevation data, 

aquifer pump tests, and hydrologic modeling. Cross sections using historical and recent 

hydrologic data also support this observation (Ref. 35, p. 2740). 

The hydrologic models also predict hydrologic communication between backfilled pits 

and the surface water – ground water system. Ground water is predicted to flow from the 

North Paguate and Jackpile pits into the Alluvial Aquifer, then into the Rio Paguate. 

Ground water from the South Paguate Pit is predicted to flow into the Jackpile Sandstone 

and the Alluvial Aquifer, with some fraction reaching Rio Paguate. This prediction is 

bolstered by the fact that ground water levels in several of the wells near the pits 

have increased up to 66 feet in the last 30 years. The rebound of the water table is 

due partially to the fact that mining activities, specifically pumping of water from 

the pit areas, ceased in 1982. Cross sections drawn through the pits illustrate the 

relationship between the excavated and backfilled pit conditions with respect to the most 

dramatically affected wells (Ref. 35, p. 2789). 

Field measurements and laboratory analysis of the ground water in the Jackpile, North 

Paguate, and South Paguate pits indicate that chemical reactions are occurring in the 

backfill that mobilize uranium in very high concentrations (four to five orders of 

magnitude higher than background surface or ground water). Ground water in the pits 

appears to be rebounding at a rate much higher than pre-remedial modeling predicted; 

ground water in the South Paguate Pit has already rebounded 10 feet above the 

elevation it was projected to reach after 150 years. Hydrologic observations and 

modeling indicate that these pit waters are not contained and will flow into the surface 

water system via ground water pathways, carrying contaminants into that system (Ref. 

35, p. 2795). [emphasis added]

Thus, the pits are no longer dry and ground water levels in the pits have clearly risen over time (coming in 

contact with the pits), and this does constitute a connection between water in the pits and surface water. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.23 Ground Water: Flow Direction/Targets 

Comment: In discussing the geologic setting of the Jackpile mine, Mr. Parkhill asserted that any 

contaminants in ground water would flow north-northwest, away from Pueblo of Laguna. 

Response: While Mr. Parkhill did not identify how this statement was related to the proposed HRS 

scoring of the Site, because the HRS documentation record at proposal presented information on the 

ground water to surface water migration component of the surface water pathway at this site, this 

comment is assumed to be addressing that component. However, the ground water to surface water 

migration component of the surface water migration pathway was not evaluated for HRS scoring 

purposes; the information provided on this component in the HRS documentation record at proposal was 

included to notify the public that this component may be of concern to the EPA and may be evaluated 

during further investigations. 

Within the ground water to surface water migration component, flow direction could have an influence on 

identifying an observed release to ground water – in particular in establishing attribution of the release to 

a site – and in assigning values to targets (which in part depends on the attribution of the release to a 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

81 

site)17. If the commenter is implying that ground water flow in the vicinity of the Site would be to the 

north/northwest and away from the Pueblo of Laguna (and would not constitute a threat to any potential 

targets there), or if the commenter is instead implying that the asserted north-northwest ground water flow 

direction would contradict the contribution of hazardous substances by site sources to the rivers via 

ground water, hydraulic data presented in the HRS documentation record at proposal indicates that 

ground water instead flows from the east-northeast to west-southwest in the western half of the mine 

facility area, and from north to south in the eastern half of the mine facility area. 

The HRS provides two options for scoring the threat posed by the migration of hazardous substances to 

surface water. HRS Section 4.0.1, Migration components, states the following:

Evaluate the surface water migration pathway based on two migration components: 

• Overland/flood migration to surface water (see section 4.1). 

• Ground water to surface water migration (see section 4.2). 

Evaluate each component based on the same three threats: drinking water threat, human 

food chain threat, and environmental threat. 

Score one or both components, considering their relative importance. If only one 

component is scored, assign its score as the surface water migration pathway score. If 

both components are scored, select the higher of the two scores and assign it as the 

surface water migration pathway score. 

As illustrated on page 55 of the HRS documentation record at proposal, the ground water to surface water 

migration component was not evaluated: 

The ground water to surface water component is presented in this section although the 

surface water likelihood and potential to release as well as the threat-targets are scored 

based on the overland/flood migration component as shown in Section 4.1 of this report. 

Since the threat of release by overland flow or flood is more than minimal for this facility 

and the component score sufficient to score the overall site, this information is presented 

as supporting information. 

However, the commenter’s assertion that ground water flow is to the north-northwest is 

inconsistent with the information presented in the HRS documentation record at proposal. As 

documented on Page 55 of the HRS documentation record at proposal: 

Hydrologic data indicate that both surface water and ground water flow from eastnortheast to west-southwest in the western half of the study area, and from north to south 

in the eastern half of the study area (Ref. 35, p. 2740)18. 

Thus, the flow direction does support the migration of hazardous substances from sources at the Site to 

the rivers via ground water (and would support the attribution of the significant increase in hazardous 

substances found in surface water to the Site by means of the ground water to surface water migration 

component, were that component scored).

 

17 See HRS Sections 4.2.2.1.1, Observed release, and 4.2.2.3, Drinking water threat-targets. 18 This statement is supported by page 2740 of the July 2011 Draft Expanded Site Inspection Report for Jackpile-Paguate 

Uranium Mine (Reference 35 of the HRS documentation record at proposal). 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

82 

Also, to the extent that the commenter means to imply that contaminated ground water from the Site 

would not constitute a threat to the Pueblo of Laguna, the ground water migration pathway was not 

evaluated in the HRS documentation record at proposal. 

This comment results in no change to the HRS score and no change in the decision to place the Site on the 

NPL.

3.24 Accuracy of the EPA Site Narrative 

Comment: ARC disagreed with several aspects of the EPA NPL Site Narrative for the Site, stating that it 

“contains statements that ARC believes are misleading, unsupported by the record and/or incorrect.” 

Response: The EPA Site Narrative reflects past and current conditions at the Site. While not part of the 

HRS package supporting the HRS evaluation of the Site, the information contained in the Site Narrative is 

consistent with the information used in the HRS evaluation of the Site. The following subsections address 

the consistency of the Site Narrative with the HRS evaluation of the Site:

• 3.24.1 Magnitude of Contamination 

• 3.24.2 Post-Reclamation Releases

• 3.24.3 Potential Impacts

• 3.24.4 List of Contaminants

3.24.1 Magnitude of Contamination

Comment: ARC took issue with the EPA NPL Site Narrative statement that “[t]here are high 

concentrations of U-238 in surface water immediately downstream of the mine.” ARC characterized this 

statement as “conclusory” and “misleading” and requested it be removed, arguing that proper background 

levels were not established in the HRS documentation record at proposal, and therefore there is no 

documentation that an observed release of isotopic uranium or manganese has occurred. ARC similarly 

argued against an EPA NPL Site Narrative statement that “[s]urface waters of the Rio Paguate and in the 

Paguate Reservoir contain elevated levels of Isotopic Uranium.” 

Response: The EPA Site Narrative descriptions of “high concentrations of U-238 in surface water 

immediately downstream of the mine” and “elevated levels” of isotopic uranium in the Rio Paguate and in 

the Paguate Reservoir are consistent with information presented in the HRS documentation record 

package. As explained in section 3.15, Likelihood of Release: Background and Significant Increase, of 

this support document and section 3.16, Likelihood of Release: Attribution, of this support document and 

its subsections, the background samples used in the HRS documentation record at proposal were adequate 

to determine background levels for the Site, and an observed release of manganese and isotopic uranium 

was correctly established, in accordance with the HRS. The observed releases showed that there are 

elevated concentrations of U-238 in surface water immediately downstream of the mine, and, surface 

waters of the Rio Paguate and in the Paguate Reservoir contain elevated levels of isotopic uranium. 

Background uranium concentrations measured in the April 2011 SI and shown on pages 38-39 of the 

HRS documentation record at proposal are summarized in the table below:
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

83 

Sample ID

Hazardous 

Substance

Conc. 

(pCi/L)

Sample 

Mean

Sample 

Standard 

Deviation

Two Standard 

Deviations 

Above The 

Mean

MD-SW-110420 Uranium234 4.858

RM-SW-BG-110419 Uranium 5.073 1.077706361 7.228412721 234 4.119

RP-SW-BG-041911 Uranium234 6.242

MD-SW-110420 Uranium235 0.306

RM-SW-BG-110419 Uranium 0.2072 0.103481013 0.414162026 235 0.0996

RP-SW-BG-041911 Uranium235 0.216

MD-SW-110420 Uranium238 2.811

RM-SW-BG-110419 Uranium 2.94466667 0.790026793 4.524720252 238 2.23

RP-SW-BG-041911 Uranium238 3.793

As explained in section 3.15, Likelihood of Release: Background and Significant Increase, of this support 

document, HRS Section 7.1.1, Observed release/observed contamination, specifies that a naturally 

occurring radionuclide concentration meets the significant increase criteria for establishing an observed 

release if it equals or exceeds a value two standard deviations above the mean background concentration. 

Pages 39-41 of the HRS documentation record at proposal show the release sample concentrations from 

the April 2011 SI; a summary is presented in the following table alongside the associated backgroundbased criteria:

Station Location Location Description

Hazardous

Substance

Observed 

Release Conc.

(pCi/L)

Two Standard 

Deviations 

Above The 

Mean 

Background

RM-JM-SW-110420

Rio Moquino, within the property, 

upstream of its confluence with 

Rio Paguate and 5,500 feet south 

of the Jackpile-Paguate Mine 

boundary at PPE3

Uranium234

Uranium235 

Uranium238

37.997

1.540

33.431

7.228412721

0.414162026

4.524720252

RM-JM-SW-02-110420

Rio Moquino, within the property, 

upstream of its confluence with 

Rio Paguate and 5,500 feet south 

of the Jackpile-Paguate Mine 

boundary at PPE3

Uranium234

Uranium235 

Uranium238

28.334

0.961

23.591

7.228412721

0.414162026

4.524720252

RP-JM-SW-11042019

Rio Paguate, within the property, 

just upstream of its confluence 

with Rio Moquino and 6,800 feet 

east of the Jackpile-Paguate Mine 

boundary and 4,900 feet from 

PPE1

Uranium234

Uranium235 

Uranium238

28.476

1.071

24.247

7.228412721

0.414162026

4.524720252

 

19 As described in section 3.10, Surface Water Pathway Description: Source 1, of this support document, because

Source 1 is no longer evaluated for the overland/flood migration component, the release samples RP-JM-SW and 

RP-JM-SW-110420 (in the Rio Paguate, upstream of the rivers’ confluence) are also no longer considered in the 

evaluation of the overland/flood migration component. However, these samples would represent an observed release 

for the ground water to surface water pathway, were it scored. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

84 

Station Location Location Description

Hazardous

Substance

Observed 

Release Conc.

(pCi/L)

Two Standard 

Deviations 

Above The 

Mean 

Background

RP-JM-SW-01-110420

Rio Paguate, within the property,

just downstream of the confluence 

of Rio Moquino and Rio Paguate, 

600 feet from PPE3

Uranium234

Uranium235 

Uranium238

32.398

1.236

29.257

7.228412721

0.414162026

4.524720252

RP-SW-01-110420 Rio Paguate, 9,500 feet. 

downstream of PPE420

Uranium234

Uranium235 

Uranium238

85.098

3.236

78.787

7.228412721

0.414162026

4.524720252

PR-SW-01-110420 Paguate Reservoir, 22,300 feet 

downstream of PPE4

Uranium234

Uranium235 

Uranium238

17.445

0.565

14.624

7.228412721

0.414162026

4.524720252

The release concentrations not only meet the observed release criterion of two standard deviations above 

the mean background concentration, but often exceed it: U-234 release concentrations are approximately 

2 to 12 times the observed release criteria value; U-235 release concentrations are approximately 2 to 8 

times the observed release criteria value; and, U-238 release concentrations are approximately 3 to 18 

times the observed release criteria value. 

Furthermore, pages 7-8 of the HRS documentation record at proposal identify that in several surface 

water samples collected at and downstream of the mine (as part of ROD Compliance Assessment 

monitoring from 1996-2006 and Water Pollution Program Grants monitoring from 2005-2009) total 

uranium concentrations have exceeded EPA Maximum Contaminant Levels (MCLs) for drinking water.

Thus, the EPA Site Narrative descriptions of “high concentrations of U-238 in surface water immediately 

downstream of the mine” and “elevated levels” of isotopic uranium in the Rio Paguate and in the Paguate 

Reservoir were consistent with information presented in the HRS documentation record at proposal (and 

are consistent with the HRS documentation record at promulgation). 

These comments on the EPA Site Narrative result in no change to the HRS score and no change in the 

decision to place the Site on the NPL.

3.24.2 Post-Reclamation Releases

Comment: ARC also criticized the EPA NPL Site Narrative statement that “[r]eleases from the mine are 

still occurring despite the reclamation of the surficial mine areas.” ARC described this language as 

“conclusory” and “unfounded” based on its challenge to background levels and establishment of an 

observed release. ARC further stated that 

[t]his statement also implicitly suggests that the mine reclamation plan as approved and 

adopted by the BLM was faithfully implemented, which is contradicted by statements in 

the HRS documentation that note non-compliance with certain requirements of the 

approved reclamation plan (For example, the heading on Page 15 “Release to Surface 

Water” last sentence states that. “...although required as part of the ROD, no berms were 

placed to control surface runoff. . . .” 

 

20 Note that this location description for sample RP-SW-01-110420 was incorrect (the sample was located at PPE4), 

and has been corrected in the HRS documentation record at promulgation.
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85 

ARC concluded that “EPA’s unsubstantiated statements in EPA’s narrative have the unfortunate potential 

to exaggerate the observed level of impacts and unnecessarily alarm the public about the potential risks 

associated with the Jackpile Mine site.” 

Response: The information presented in the HRS package at proposal regarding ongoing releases from the 

Site is sufficient to document that releases have occurred after any reclamation activities. Given that site 

conditions have not changed significantly since these releases were identified, and that ARC has not 

presented any information to the contrary, it is reasonable to state that releases are ongoing at the Site. As 

explained on pages 7-9 of the HRS documentation record at proposal, the most recent observed release 

samples shown were water samples collected in April, 2011, well after reclamation actions took place and 

the reclamation project was closed in 1995 (and constitute current releases since the hazardous substances

were found in samples of water that is flowing). 

The NPL Site Summary phrase “despite the reclamation of the surficial mine areas” does not necessarily 

mean that reclamation is absolutely complete or that reclamation activities have proven absolutely 

effective; furthermore, the reclamation activities also do not address potential releases to ground water 

and from ground water to surface water at the Site. The NPL Site Summary also clearly states that a 2007 

Record of Decision Compliance Assessment found that reclamation was not complete. The need for 

further cleanup efforts is determined in a different stage of the Superfund process. 

These comments on the EPA Site Narrative result in no change to the HRS score and no change in the 

decision to place the Site on the NPL.

3.24.3 Potential Impacts

Comment: ARC objected to the EPA NPL Site Narrative statement that: 

[s]urface waters of the Rio Paguate and in the Paguate Reservoir contain elevated levels 

of Isotopic Uranium. Fishing has been documented at the reservoir and downstream in 

the Rio San Jose. The levels of Isotopic Uranium could have an impact on 

Traditional/Cultural and Ceremonial uses of surface water bodies below the convergence 

of the Rio Paguate.”

ARC again cited its challenge to background levels and establishment of an observed release, concluding 

that the EPA should remove language discussing impacts of elevated levels of isotopic uranium on fishing 

in the Reservoir and downstream Rio Paguate and “non-specific and speculative impacts on Traditional/ 

Cultural and Ceremonial uses of surface water bodies below the convergence of the Rio Paguate.” ARC 

added that “[t]he HRS Documentation provides nothing more than anectodal [sic] notes related to 

assumed fish biomass, fishing activity within and downstream from the Jackpile Mine and there is no 

mention of Traditional/Cultural and Ceremonial uses of surface water.” 

Response: That the release of uranium from the mining operations “could have” an impact on the users of 

the Rio Paguate and the Paguate Reservoir for fishing and cultural activities is supported by the 

information presented in the HRS documentation record at proposal. This description of potential effects 

is reasonable because:

• As explained in section 3.18, Human Food Chain Threat: Evidence of Fishing for Consumption, 

of this support document, fishing for human consumption has been correctly established in the 

Paguate Reservoir and portions of the Rio Moquino, Rio Paguate, and Rio San Jose within the 

target distance limit and the zone of actual contamination, consistent with the HRS.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

86 

• As explained in section 3.24.1, Magnitude of Contamination, of this support document, there are 

concentrations of isotopic uranium in surface water at and downstream of the Site that are 

elevated relative to background levels.

• As explained in section 3.16, Likelihood of Release: Attribution, of this support document and its 

subsections, some portion of the significant increase in hazardous substances found in surface 

water is correctly attributed to the Site, consistent with the HRS.

• Uranium is a hazardous substance listed in 40 CFR 302.4, the list of hazardous substances under 

section 102(a) of CERCLA as those substances in the statutes referred to in CERCLA section 

101(14). 

• Uranium is associated with health impacts and is known to bioaccumulate in fish tissue and thus 

the consumers of the fish are potentially exposed to higher concentrations of uranium than those 

found in the ambient water bodies. Page 48 of the HRS documentation record at proposal presents 

HRS factor values for toxicity and bioaccumulation of uranium isotopes.21 

Therefore the release of uranium could have an effect on downstream fisheries and the people that 

consume fish caught in those fisheries.

Regarding traditional/cultural and ceremonial uses of surface water bodies, page 2 of Reference 23 of the 

HRS documentation record at proposal notes that “[t]raditional uses and taking of water fowl have been 

also been observed on a routine and continuing basis.” Furthermore, pages 1 and 5 of Reference 42 of the 

HRS documentation record at promulgation (a memorandum from Curtis L. Francisco of the Pueblo of 

Laguna Environmental and Natural Resources Department) contain statements confirming tribal 

members’ cultural use of the Rio Paguate and Rio Moquino upstream and downstream of the Jackpile 

Mine site. These pages note that “Tribal members continue to use the Rio Paguate below the Jack Pile 

Mine site for cultural, ceremonial and traditional use,” that there may be “immersion and consumption of 

the water,” and that 

[w]ater is a valuable resource for the Pueblo of Laguna especially in the current drought. 

Water is used and livestock and wildlife eat vegetation along it and wild food plants that 

grow along waterways are collected and consumed, used for basketry and wood from the 

trees is used to heat home and cook with in wood stoves and outside ovens (hornos). 

These comments on the EPA Site Narrative result in no change to the HRS score and no change in the 

decision to place the Site on the NPL.

3.24.4 List of Contaminants

Comment: ARC challenged the list of contaminants in the Contamination/Contaminants section of the 

EPA NPL Site Narrative (which include uranium [U-234, U-235 and U-238] arsenic, barium, chromium, 

cobalt, copper, lead, manganese, vanadium, selenium, and zinc.) ARC claimed that this list is more 

extensive than what is documented in the HRS documentation record at proposal (pointing to isotopic 

uranium and manganese), and that “[t]here is no basis to discuss any other compounds other than those 

used specifically for the HRS scoring for surface water pathway.” 

 

21 Reference 2 is cited to support these values. Page 17 of that reference shows a surface water pathway human food 

chain reference dose screening concentration. Page 5 of Reference 2 explains that these factor values are sourced 

“from peer reviewed, generally accepted literature sources and databases and/or EPA-developed literature sources 

and databases; or are calculated using procedures set forth by EPA and in the HRS. 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

87 

Response: The majority of the substances listed in the EPA Site Narrative are associated with the Site 

based on data presented in the HRS documentation record at proposal and associated references. 

Although only manganese and isotopic uranium were used to establish observed releases to the surface 

water pathway in the HRS documentation record at proposal, the presence of other hazardous substances 

was identified in source material. Chromium, cobalt, manganese, vanadium, and zinc were found in 

Source 1 samples, and vanadium was found in Source 2 samples (as shown in tables on pages 18 and 23 

of the HRS documentation record at proposal). And the HRS documentation record at proposal 

establishes that these hazardous substances are available to migrate to the surface water pathway from 

these sources because the containment features for the sources are incomplete for HRS purposes.22

Additionally, the EPA Site Narrative has been revised to remove those analytes not presented in the text 

of the HRS documentation record at proposal: arsenic, barium, copper, lead, and selenium. 

These comments on the EPA Site Narrative result in no change to the HRS score and no change in the 

decision to place the Site on the NPL.

3.25 Waste Characteristics

As described in Section 3.10, Surface Water Pathway Description: Source 1, of this support document, 

after consideration of comments questioning the inclusion of Source 1 as a source of hazardous 

substances to surface water via overland runoff, the EPA has removed Source 1 from the evaluation of the 

surface water pathway overland/flood migration component in the HRS documentation record at 

promulgation. The effects of this change on the waste characteristics factor category values are explained 

in the following subsections: 

• 3.25.1 Drinking Water Threat Waste Characteristics

• 3.25.2 Human Food Chain Threat Waste Characteristics

As explained in these subsections, there is no change to the waste characteristics factor category values 

for either the drinking water threat or the human food chain threat; and thus the removal of Source 1 from 

evaluation of the overland/flood migration component results in no change to the Site score or the 

decision to place the Site on the NPL.

3.25.1 Drinking Water Threat Waste Characteristics

As described in Section 3.10, Surface Water Pathway Description: Source 1, of this support document, 

Source 1 has been removed from the evaluation of the surface water pathway overland/flood migration 

component in the HRS documentation record at promulgation. Therefore, the Source 1 source hazardous 

waste quantity value and hazardous substances (including radium) available to migrate from Source 1 to 

surface water via the overland/flood component are no longer considered in the calculation of the waste 

characteristics factor category value for the drinking water threat. 

However, as detailed below, these changes result in no effect on the drinking water threat waste 

characteristics factor category value. 

HRS Section 4.1.2.2, Drinking water threat-waste characteristics, states to 

 

22 Pages 15 and 21 of the HRS documentation record at proposal identify that there is no maintained engineered 

cover, liner, and a run-on control system and runoff management system for Source 1 and Source 2.
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

88 

Evaluate the waste characteristics factor category for each watershed based on two 

factors: toxicity/ persistence and hazardous waste quantity. Evaluate only those 

hazardous substances that are available to migrate from the sources at the site to surface 

water in the watershed via the overland/flood hazardous substance migration path for the 

watershed (see section 4.1.1.1). Such hazardous substances include:

• Hazardous substances that meet the criteria for an observed release to surface water 

in the watershed.

• All hazardous substances associated with a source that has a surface water 

containment factor value greater than 0 for the watershed (see sections 2.2.2, 2.2.3, 

4.1.2.1.2.1.1, and 4.1.2.1.2.2.1). 

On determining a toxicity/persistence factor value, HRS Section 4.1.2.2.1.3, Calculation of 

toxicity/persistence factor value, states to: 

Assign each hazardous substance a toxicity/persistence factor value from Table 4–12, 

based on the values assigned to the hazardous substance for the toxicity and persistence 

factors. Use the hazardous substance with the highest toxicity/ persistence factor value 

for the watershed to assign the toxicity/persistence factor value for the drinking water 

threat for the watershed.

 . . . a Table 4–12—Toxicity/Persistence Factor Values

Persistence factor value 

Toxicity factor value

10,000 1,000 100 10 1 0 

1.0 10,000 1,000 100 10 1 0 

0.4 4,000 400 40 4 0.4 0 

0.07 700 70 7 0.7 0.07 0 

0.0007 7 0.7 0.07 0.007 0.0007 0 a

Do not round to nearest integer. 

As shown on page 47 of the HRS documentation record at promulgation, the toxicity/persistence factor 

values are:

Hazardous

Substance

Source 

Number

Toxicity 

Factor

Value

Persistence1

Factor Value

Toxicity/

Persistence/ Reference

Manganese 2 10,000 1 10,000 Ref. 2, p. 10

Vanadium 2 100 1 100 Ref. 2, p. 13

Uranium234 2 10,000 1 10,000 Ref. 2, p. 16

Uranium235 2 10,000 1 10,000 Ref. 2, p. 16

Uranium238 2 10,000 1 10,000 Ref. 2, p. 16

Notes:

1 All hazardous substances were assigned the same persistence factor value (i.e., 1.0000) for both water 

body types (river and lake) within the TDL (Ref. 1, Table 4-10).

The highest toxicity/persistence factor value remains the same as that assigned at proposal: 10,000 (based 

on all five hazardous substances in the table above).
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

89 

On determining hazardous waste quantity for the overland/flood migration component, HRS Section 

4.1.2.2.2, Hazardous waste quantity, states to “[a]ssign a hazardous waste quantity factor value for the 

watershed as specified in section 2.4.2.” HRS Section 2.4.2.1, Source hazardous waste quantity, states in 

relevant part “[f]or each of the three migration pathways, assign a source hazardous waste quantity value 

to each source (including the unallocated source) having a containment factor value greater than 0 for the 

pathway being evaluated.” 

As shown on page 24 of the HRS documentation record at proposal, a hazardous waste quantity value of 

43,560 was assigned for Source 2. 

HRS Section 2.4.2.2, Calculation of hazardous waste quantity factor value, then states to:

Sum the source hazardous waste quantity values assigned to all sources (including the 

unallocated source) or areas of observed contamination for the pathway being evaluated 

and round this sum to the nearest integer, except: if the sum is greater than 0, but less 

than 1, round it to 1. Based on this value, select a hazardous waste quantity factor value 

for the pathway from Table 2–6. 

Table 2–6—Hazardous Waste Quantity Factor Values

Hazardous waste quantity value Assigned value

0 0 

1a to 100 1b

Greater than 100 to 10,000 100 

Greater than 10,000 to 1,000,000 10,000 

Greater than 1,000,000 1,000,000 a

If the hazardous waste quantity value is greater than 0, but less than 1, round it to 1 as specified in text. b

For the pathway, if hazardous constituent quantity is not adequately determined, assign a value as 

specified in the text; do not assign the value of 1.

For a migration pathway, if the hazardous constituent quantity is adequately determined 

(see section 2.4.2.1.1) for all sources (or all portions of sources and releases remaining 

after a removal action), assign the value from Table 2–6 as the hazardous waste quantity 

factor value for the pathway. If the hazardous constituent quantity is not adequately 

determined for one or more sources (or one or more portions of sources or releases 

remaining after a removal action) assign a factor value as follows:

• If any target for that migration pathway is subject to Level I or Level II 

concentrations (see section 2.5), assign either the value from Table 2–6 or a value of 

100, whichever is greater, as the hazardous waste quantity factor value for that 

pathway. 

• If none of the targets for that pathway is subject to Level I or Level II concentrations, 

assign a factor value as follows:

- If there has been no removal action, assign either the value from Table 2–6 or a 

value of 10, whichever is greater, as the hazardous waste quantity factor value for 

that pathway. 

- If there has been a removal action:

- Determine values from Table 2–6 with and without consideration of the 

removal action.

- If the value that would be assigned from Table 2–6 without consideration of the 

removal action would be 100 or greater, assign either the value from Table 2–6 
Jackpile-Paguate Uranium Mine NPL Listing Support Document December 2013 

90 

with consideration of the removal action or a value of 100, whichever is 

greater, as the hazardous waste quantity factor value for the pathway.

- If the value that would be assigned from Table 2–6 without consideration of the 

removal action would be less than 100, assign a value of 10 as the hazardous 

waste quantity factor value for the pathway.

As shown on page 48 of the HRS documentation record at promulgation, based on the sum of source 

hazardous waste quantity values (43,560), a hazardous waste quantity factor value of 10,000 is assigned. 

On determining the waste characteristics factor category value, HRS Section 4.1.2.2.3, Calculation of 

drinking water threat-waste characteristics factor category value, states to:

Multiply the toxicity/persistence and hazardous waste quantity factor values for the 

watershed, subject to a maximum product of 1×108

. Based on this product, assign a value 

from Table 2–7 (section 2.4.3.1) to the drinking water threat-waste characteristics factor 

category for the watershed. . . . 

HRS Table 2-7 states:

Table 2–7—Waste Characteristics Factor Category Values

Waste characteristics product Assigned value 

0 0 

Greater than 0 to less than 10 1 

10 to less than 1×102 2 

1×102to less than 1×103 3 

1×103to less than 1×104 6 

1×104to less than 1×105 10 

1×105to less than 1×106 18 

1×106to less than 1×107 32 

1×107to less than 1×108 56 

1×108to less than 1×109 100 

1×109to less than 1×1010 180 

1×1010to less than 1×1011 320 

1×1011to less than 1×1012 560 

1×1012 1,000 

As shown on page 48 of the HRS documentation record at promulgation, the product of the 

toxicity/persistence and hazardous waste quantity factor values is 1 x 108

. The resulting hazardous waste 

characteristics factor category value from HRS Table 2-7 remains 100, as was assigned at proposal. 

Therefore, the removal of Source 1 from the evaluation of the overland/flood migration component results 

in no change to the drinking water threat waste characteristics factor category value; and with respect to 

this factor category value, there is no change in the Site score or the decision to place the Site on the NPL.
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91 

3.25.2 Human Food Chain Threat Waste Characteristics

As explained in section 3.10, Surface Water Pathway Description: Source 1, of this support document, 

Source 1 has been removed from the evaluation of the surface water pathway overland/flood migration 

component in the HRS documentation record at promulgation. Therefore, the Source 1 source hazardous 

waste quantity value and hazardous substances (including radium) available to migrate from Source 1 to 

surface water via the overland/flood component are no longer considered in the calculation of the waste 

characteristics factor category value for the human food chain threat. 

However, as detailed below, these changes result in no effect on the human food chain threat waste 

characteristics factor category value. 

HRS Section 4.1.3.2, Human food chain threat-waste characteristics, states to “[e]valuate the waste 

characteristics factor category for each watershed based on two factors: 

toxicity/persistence/bioaccumulation and hazardous waste quantity.” HRS Section 4.1.3.2.1, 

Toxicity/persistence/bioaccumulation, then specifies to “[e]valuate all those hazardous substances eligible 

to be evaluated for toxicity/persistence in the drinking water threat for the watershed (see section 

4.1.2.2).” 

On determining the toxicity/persistence/bioaccumulation factor value, HRS Section 4.1.3.2.1.4 

Calculation of toxicity/persistence/bioaccumulation factor value, states: 

Assign each hazardous substance a toxicity/persistence factor value from table 4–12, 

based on the values assigned to the hazardous substance for the toxicity and persistence 

factors. Then assign each hazardous substance a toxicity/persistence/bioaccumulation 

factor value from table 4–16, based on the values assigned for the toxicity/persistence and 

bioaccumulation potential factors. Use the hazardous substance with the highest 

toxicity/persistence/bioaccumulation factor value for the watershed to assign the value to 

this factor.

As shown on page 49 of the HRS documentation record at promulgation, the 

toxicity/persistence/bioaccumulation factor values are:

Hazardous

Substance

Source 

Number

Toxicity 

Factor

Value

Persistence1

Factor 

Value

Human Food 

Chain

Bioaccumulation 2

Value

Toxicity/

Persistence/

Bioaccumulation 

Factor Value

Reference

Manganese 2 10,000 1 50,000 5 x 108 Ref. 2, p. 10

Vanadium 2 100 1 500 5 x 104 Ref. 2, p. 13

Uranium234 2 10,000 1 0.5 5,000 Ref. 2, p. 16

Uranium235 2 10,000 1 0.5 5,000 Ref. 2, p. 16

Uranium238 2 10,000 1 5,000 5 x 107 Ref. 2, p. 16

Notes:

1 All hazardous substances were assigned the same persistence factor value (i.e., 1.0000) for both water body 

types (river and lake) within the TDL (Ref 1, Table 4-10). 2 Bioaccumulation factor values are assigned from the SCDM (Ref. 2), for the type of water body "Fresh Water”, 

in which the fisheries are located (Ref. 1, Sect. 4.1.3.2.1.3).

The highest toxicity/persistence/bioaccumulation factor value is 5 x 108

, based on manganese.
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92 

HRS Section 4.1.3.2.2, Hazardous waste quantity, instructs to “[a]ssign the same factor value for 

hazardous waste quantity for the watershed as would be assigned in section 4.1.2.2.2 for the drinking 

water threat.” Accordingly, page 50 of the HRS documentation record at promulgation assigns the 

hazardous waste quantity factor value of 10,000. 

On determining the waste characteristics factor category value, HRS Section 4.1.3.2.3, Calculation of 

human food chain threat-waste characteristics factor category value, states: 

For the hazardous substance selected for the watershed in section 4.1.3.2.1.4, use its 

toxicity/persistence factor value and bioaccumulation potential factor value as follows to 

assign a value to the waste characteristics factor category. First, multiply the 

toxicity/persistence factor value and the hazardous waste quantity factor value for the 

watershed, subject to a maximum product of 1×108

. Then multiply this product by the 

bioaccumulation potential factor value for this hazardous substance, subject to a 

maximum product of 1×1012. Based on this second product, assign a value from Table 2–

7 (section 2.4.3.1) to the human food chain threat-waste characteristics factor category 

for the watershed.

The assignment of the waste characteristics factor category value for the human food chain threat is as 

follows, as shown on page 50 of the HRS documentation record at promulgation, resulting in a value of 

1,000 – the same as that assigned at proposal: 

Toxicity/Persistence Factor Value: 10,000 

Hazardous Waste Quantity Factor Value: 10,000 

Bioaccumulation Potential Factor Value: 50,000 

10,000 (Toxicity/Persistence Factor Value) x 10,000 (Hazardous Waste Quantity Factor Value) = 

1 x 108

 (maximum of 1 x 108 according to HRS Section 4.1.3.2.3) 

1 x 108 (Toxicity/Persistence Factor Value x Hazardous Waste Quantity Factor Value) x 

50,000 (Bioaccumulation Potential Factor Value) = 5 x 1012 (maximum of 1 x 1012 according to 

HRS Section 4.1.3.2.3) 

A hazardous waste quantity factor value of 10,000 is assigned according to HRS Section 2.4.2.2. 

From Reference 2 and Table 4-12 of the HRS, manganese has a toxicity/persistence value of 

10,000 and a bioaccumulation potential factor of 50,000. The waste characteristics factor 

category value from Reference 1, Table 2-7 for a waste characteristics product of 1 x 1012 is 

1,000. 

Waste Characteristics Factor Category Value: 1,000 

Therefore, the removal of Source 1 from evaluation of the overland/flood migration component results in 

no change to the human food chain threat waste characteristics factor category value and no change to the

Site score or the decision to place the Site on the NPL.
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93 

4. Conclusion

The original HRS score for this site was 50.00. Based on the above responses to public comments, the 

score for the Site remains unchanged. The final scores for the Jackpile-Paguate Uranium Mine site are:

Ground Water Migration Pathway: Not scored

Surface Water Migration Pathway: 100.00 

Soil Exposure Pathway: Not scored

Air Migration Pathway: Not scored

HRS Score: 50.00