United States
Environmental Protection Agency 

# EPA 1200 Penn sylvaniaAvenue, 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 20460Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

i 

## Table of Contents

Executive Summary

................................................................................................ ................................................ iii

Introduction

............................................................................................................................................................ iv

Background of th e 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 Su pport 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 ...............................................26Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

ii 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 o f 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 S urface 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 ......................................................................................................................................................93Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

iii 

## 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 doc ument 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 pub lished in the Federal Register in December 2013.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

iv 

## 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 t o 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 Liabilit y 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, 198 1). 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 throug hout 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 ta ken 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 sever al 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 purpos e 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]).Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

v The priority list serves primarily informational purposes, identifying for the St ates 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 ass ociated with the site and to determine what CERCLA

financed 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 doe s 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 principa l 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 pos e 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 exte nt 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 requir e 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

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

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

• Ground Water Migration (S gw )Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

vi • Surface Water Migration (S

sw ) 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 (S

s )

- resident population - nearby population

• Air Migration (S

a ) - 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

I f all pathway scores are low, the HRS score is low. However, the HRS score can be relatively high ev en 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 we lls, 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 sign ificant 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 response s 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 r esponses to each comment. A concluding statement indicates the effect of the comments on the HRS score for the S ite.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

vii 

### Glossary

The following acronyms and abbreviations are used throughout the text:

Agency U.S. Environmental Protection Agency

AMC Anacond a 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

E IS Environmental Impact Statement

EPA U.S. Environmental Protection Agency

E SI 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 Maxi mum Contaminant Level

mg/l M illigram 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 I nvestigation

RI/FS Remedial Investigation/Feasibility Study

R OD Record of Decision

SARA Superfund Amendments and Reauthorization Act

SCDM Superfund Chemical Data MatrixJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

viii SI Site Inspection

SQL Sample Quantitation L imit

TDS Total Dissolved Solids

TDL Target Distance L imitJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

1 

## 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

- SFUN D-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

Richfiel d 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 Moqu ino 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 pu rpose 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 protore 1 st ockpiles . 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 m ining, 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, approximatel y 40 miles west of the proper ty

.

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

2 topography that contains wildlife consisting of elk, antelope, goats, and mule deer. There is also a population of approximately 1,500 domesticated c attle 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 fo llowing: 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 ro ck 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 o f 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, ligh t manufacturing, office space, mining, and major equipment
storage. H abitation 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 Corpora tion 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 p art 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 bee n collecting surface water samples along the surface water pathway quarterly from 2005 through 2009. During th ese evaluation s , several samples exhibited uranium and manganese contamination in the Rio Moquino, Rio Paguate, Paguate Reservoir, and Rio San Jose. These

results indicate d contamination w ithin 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 theJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

3 presence of various hazardous substances associated with this mining waste, including uranium, thorium, and radium radionuclide isotopes (uraniu m-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 proposa l 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 surf ace 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 contami nants 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.Jackpile -Paguate Uranium Mine NPL L isting Support Document December 2013

4Jackpile -Paguate Uranium Mine NPL L isting Support Document December 2013

5Jackpile -Paguate Uranium Mine NPL L isting Support Document December 2013

6Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

7 

## 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 rem ediation 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 projec t 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 Drinkin g Water Standards, as the National Secondary

Maximum Contaminant Level (MCL) for manganese; and the human health/environmental concern posed by m anganese is questionable.

ARC further made several comments questioning whether the available information use d 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 w ater 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 run off samples should have been collected to quantify source contribution of

hazardous subst ances to the surface water.

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

to the S ite

.

• Because an HRS documentatio n 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.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

8 • T he EPA must present and take into account evidence of metals concentrations prior to mining

activities in order to attribute the observed re lease to mining operations.

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

ARC submitted comments related to the liabilit y 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 su bject, 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

con tamination.

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, c overed with top soil, and partially re

- vegetated. Mr. Parkhill noted that in a previous visit to the S ite, 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 grou nd 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 prop erly score the Jackpile site.” ARC asserted that this deficiency impact s 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 surfac e water background samples was not adequate to determine background levels for the S ite and not representative of Site conditions.

• The background samples do not adequately address the metals contributed to surface water by naturally occurring rock formati ons 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:Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

9 • A RC 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 uran ium -bearing ground water discharging from the underlying Jackpile sandstone and mixing with the surface

water.

• ARC reasoned that t he HRS documentation record should have documented uranium and manganese levels before mining operations began to show that o bserved releases are due to

mini ng 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. Park hill posited that e levated 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 docume ntation 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 sourc e 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 inappro priate 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 t he EPA NPL Site Narrative statement s regarding high levels of uranium in surface water

downs tream of the mine and post

- reclamation releases are inaccurate, based on ARC’s assertions questioning the establishment of an observed releas e 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 th ose same challenges to the observed release establishment , and challenges to documentation of

these s urface 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 fo r 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 o f 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 remediat ion.

• 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 S ite.

• A request that the Site be dealt with before any other new mines or mills are allowed to operate i n the Grants Minera l Belt.

Response: T he 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 Ac curacy 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 mention ed 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 describ e 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 i nappropriately 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 S ite, the information in ARC’s comments have also been added to the public record for the S ite.

Regar ding 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 suppo rt 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 healt h 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

ove rsight.” 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.”

Res ponse: 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 De cember 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 Projec t 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. A lso, 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

NP L

.

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–approve d 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 H RS documentation record at proposal, Site Summary section, note s 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 relate d 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 S ite 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 a pproval of federal agencies.

Respo nse : 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 state s 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:

R eclamation 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 r evegetation 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 S ite, page 26 of the HRS documentation record at proposal further explain s 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 recla imed 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 re

sloped, 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 no t 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, rec lamation or other activities ( various mitigation/improvement measures that have taken place at the S ite ) 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 sta ndards 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 • T hus, the manganese concentrations do not pose a threat to huma n health or the environment.

• The EPA was arbitrary to rely on this comparison to support listing the S ite 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 environmen t 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 investigatio ns (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 u se 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 too l 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 investi gation 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 adeq uately 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

A s 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 cri teria.

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 specifica lly 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 substan ce 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 W aste 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 302.4 2 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 ch aracteristics , 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/text

idx?c=ecfr&SID=eea576297c24e12601cff27d7803cffe&rgn=div8&view=text&node=40:29.0.1.1.2.0.1.4&idno=40Jackpile -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/
bi oaccumulation

, refers back to HRS section 4.1.2.2 quoted above, stat ing 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 identifi ed in Source 2, as shown in analytical results presented on page 23 of the HRS documentation record at proposal 3 ; pages 21

- 22 of the HRS documentation record at proposal show that a containment value of 10 w as 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 c omment 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. T here 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 t hat 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, t he 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 o nly 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 si te 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 sectio n 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, hazardo us 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 no t
af

fected.

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 av ailable 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 th e 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 S ite.

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 i nexpensive, 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

do cumentation record at proposal is sufficient for the purposes of listing a site on the NPL , including the following assertions:

• I nsufficient 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

.

• F urther 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 • S t orm water runoff samp les should have been collected to quantify source contribution of

hazardous subst ances to the surface water.

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

to the site.

• B ecause 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 m etals concentrations prior to mining

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

• The EPA should have collected tissue samples to support bi oaccumulation 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 state s:

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 believe s 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, 99 th
Cong. 2 nd 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 certai nty 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 I ndustries, 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

H RS 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 S ite are discussed in other sections of the support document; and in each case, the level of information used to

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

• T he number of samples collected to characterize sources and determine background levels for surface water and ground water is addressed in the following section s of this support docu ment :

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

• W hether runoff c an 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 ru noff samples is addressed in section s 3.16.7, Attribution to a Source, and 3.16.8, Storm Water Runoff Data, of this support document.

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

of Wind D eposition , of this support document.

• The screening of natural sources of contamination and the need for metals concentrations prior to mining are addressed in section s 3.16.1 , Background Samples Screening of Natural Levels, and 3.16.4, Consideration of Naturally Occurri ng Releases, of this support document.

• T he 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.

Th ese 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 S ite.

ARC commented that the Site Summary of t he 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

B ureau of Land Manageme nt 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 documen tation record exemplifies the failure to “analyze or describe” the extent the Pueblo managed reclamation project (with the direct involvement of the federal government) was c onsistent with or deviated from the federal government-approve d 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 r esponsible for further action and not the “taxpayers and companies who fun ded” 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 act ion(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 exp lained in the Federal Register (48 FR 40 674, 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 consi dered 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

con stitutes 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 secti on 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 is sue of uranium contamination. Mr. Parkhill stated that:Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

21 [r] ec lamation will never completely eliminate this problem because the Morrison

formatio n 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 probabl y the source of all Uranium and other metals contaminants in this area and there is no known way to sto p this problem.

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

and that further reclamation wo rk at the Jackpile Mine and Paguate Mine would be a huge waste of taxpayers' money

. ”

Response: T he NPL listing itself does not represent a finding that remedial action is necessary or will be taken; decisions on conducting response actions are made durin g the RI, when more information is collected (and contributions of hazardous substances from naturally occurring sources would be taken

into accoun t). 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 ste ps 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 he alth 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 H RS, and some portion of the significant

increase in hazardous substances is attributable to the S ite (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 pre sent the current conditions of the S ite

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 S ite.

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

A naconda 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 federalJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

22 government oversight.” This reclamation project was called the Jackpile

- P aguate Reclamation Project.

• AMC provided the Pueblo of Laguna with funds “that substantially exceeded the Bureau of Land Management reclamation estimate.”

• The Si te 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 DOI

approved 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 a pproval 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 wi th 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 sta nding 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 t he 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 (an d 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.

T he 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 S ite.

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 impacts 4 . This approach is reasonable as it e nsures that the risk posed by

released hazardous subst ances 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, tit led “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

pos sible 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 rulemaki ng, consistent with its policy quoted above, the reclamation actions discussed by the commenter result in no change to the HRS site score.

Furthermore, r egarding 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 Jackpile

Paguate Uranium Mine was completed by OA Systems Corporation to determine if the
post- reclamation had met the requiremen ts 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 quo te 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

bui lt 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 thr eat 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 w ell 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 R egarding 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 plac e 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 t hat 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 exte nt
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 we re 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 fo r 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

S ite s core, 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 bel ieves 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 S ite score in the HRS documentation record at promulgation. However, Source 1 re mains 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 S ite 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

qua ntity. As explained in section s 3.25.1, Drinking Water Threat Waste Characteristics, and 3.25.2,

Human Food C hain 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

listi ng 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 evalu ation 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

mile s 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 e ffect on the targets evaluated ( i.e., targets evaluated as subject to actual Level II contamination and targets evaluated as subject to potential contam ination 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. Thes e samples

w ere previously scored observed release samples in the HRS documentation record at proposal, b ut 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, th e se sample s would represent an observed release for that component ; the significant increase in hazardous substances identified in th ose sample s would be attributable to Source 1 North and South pits, waste materials in contact with the Rio Paguate 5 , and historical runoff from the North and South pits over the course of their mining. The removal of sample s 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 th ose sample s 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

ove rland/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 a s an eligible site source.

5 See page 13 of Reference 7 of the HRS documentation record at proposal, which explains that within th e 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 p its

.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

ch anges in the HRS evaluation of the Site result in no change to the S ite 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 HRS 6 . Th e 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 place d, 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 sourc es , 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 sourc e when evaluating each pathway.

Page 14 of the HRS documentation record at proposal describe s Source 1 a s 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 eli g ible source for the ground

water to surface water migration component of the s urface 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 a s 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 portio n 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. 2 9). 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 place d 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.

Further more , although not required by the HRS, at leas t 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 detect ed in 4 of 7 samples, and in all 3 pits

• Cobalt was detected in 2 of 7samples, both in the North Paguate P it

• 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 P it

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 , sam ples from each Source 1 pit and the Source 2 waste dump were presented, documenting the presence of hazardous substances in these sources, c onsistent 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 sample s ; background samples are not needed for waste samples when associat ing

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 asso ciation

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

• t oo 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 refl ect 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

mea sure as follows:Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

30 • F or 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 path way 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 det ermine the mass of all CERCLA

eligible 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 tha t 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 evaluate d o n 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 43,5 60 (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 Cha racteristics , 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 S ite score at promulgation.)Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

31 T his comment results in no change to the HRS si te 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 in sufficient 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 th at “[l]imited data may not reflect the actual variation and could incorrectly

in dicate 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 l onger 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 be low. 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 Si te

, 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 contamina ted 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 identif ied 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 instruc t ions 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), bu t 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 prese nt 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

subs tances 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 mini ng 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 propos al 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 i nto the pits (North Paguate Pit, South Paguate Pit, and Jackpile Pit) and used as backfill (Ref. 5, pp. 31, 32). [emphasis added]Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

33 T he HRS documentation record at proposal clearly acknowledges that the materials from the wa ste 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 slope s 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- Pagua te 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 p ose a risk at the Site. Additionally, it is not

demonstrated that remediation carried out at the Site has addressed all hazardous substance migration

from the se 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 sou rces.”

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 C onceptual S ite 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 f or 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 ari d 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 se t out below, the HRSJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

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 co ncern 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 Seboyet a 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 nea r 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 2,0 00 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 channe l 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 intermitt ently 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 eph emeral) portion s – 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, stat ing:

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 join s the Rio San Jose approximately one mile southwest of the reservoir.

However, p ages 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

intermittent ly 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 sou th en d 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 o f 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 time s 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’ inters ects 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 event 7 . 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 S ite and did no t 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,

Establ ishing 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 Re ference 36 of the HRS documentation record at proposal, showing a note that the stream was dry at location RP

- 02 in April

2011.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

36 ARC concluded that the observed release factor category value of 550 is an “overestimation based on

l imited sampling and does not represent act ual 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 contain s 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 sa mples 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 in crease 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 ar e 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 Repre sentative of the

Area

• Summary

Comments regarding the cause of the significant increase are addressed in section 3.1 6, 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 envir onment 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 s ignificantly 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 con centrations.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

37 - F or 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 sedimen ts 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 sa mples 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. F urther, 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 pe r 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 site

specific 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

38 -- Some portion of the increase must be attributable to the site to establish th e

o bserved 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, ba ckground 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

downstream 8 of the mine operations, and thus re presentative 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, attr ibution 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 discuss es 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 backg round 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 be fore 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 do wnstream 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.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

39 collected from Rio Paguate is compared to site

- r elated sediment and surface water samples collected from Rio Moquino, Rio Paguate, and the Paguate Reservoir.

• Me sita 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; Figure s 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 o f 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 state s:

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 collectedJackpile -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, backgroun d 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

T he 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 substance s, 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 compara ble 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:

EP A SI Back ground Surface Water Sample Concentrations – March 2010

Station

Location Hazardous
Substance Concentration (mg/l) 1 Reporting

Limit 2 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

Limit 2 Units 1 Reference

Rio Moquino

RM

- SW

- BG

- 110419 Uranium 234

Uranium 235

Uranium 238 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 Uranium 234

Uranium 235

Uranium 238 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 Uranium 234

Uranium 235

Uranium 238 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

, indicate s that they accurately reflect the surfa ce 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 ment ion 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 specifi c 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 wat er ( 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 ad dress 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

rele ase samples be collected within the same time frame, be of similar type, be exposed to similarJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

42 environmental conditions). B ackground 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 fo od 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 s ite sources. And, t he 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 s ite 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 S ite and site

sources , and the HRS documentation record at proposal presents reasonable evidence supporting the

attribut ion 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 attribut ion 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 chemicalJackpile -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).

T he minimum standard to establish an observed release by chemical analysis is analytical evidence of a hazardous substance in the media significan tly 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 eith er 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 mate rial 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 es tablish 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,

g round 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 pe r 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 site

specific 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 contamin ation.

I t 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

com menter.

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 s ite sources:

As part of an environmental assessment of the Jackpile

- Paguate Uranium Mine fa cility 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 with in the former mine area (Ref. 19, Figure A -5A). The solid waste samples contained uranium 238
as high as 367 ug/g and manganese as high as 270 mg/kg. The liquid waste sample

contained uranium 238 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 uranium 238 and 0.25 mg/l for manganese (see Section 2.4.1.2.1.1 of this HRS

do cumentation 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 explain s 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 withJackpile -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,

s traightening the course of the meandering stream (Ref. 4, p. 102). It appears that normal practice was to stockpile waste material in the Rio Mo quino’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 ins tability 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 stabil ization 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 uns uccessful; 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 was te 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

Sec tion 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 documentat ion record a t 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

ev aluated, the Site score would not change i f 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 fish ery 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 sub sections:

• 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

3.1 6 .1 Background Samples Screening of Natural Leve ls

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 categor y 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 leve ls 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 f ormations 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 theJackpile -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 mine

derived 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 boun daries. 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 so urce 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 Anacond a 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 o f 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 subst ance concentrations in surface water as it moves downstream through the S ite, 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 presen ted 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 calc ulated:

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

r eplaced 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 thatJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

49 background surface water samples were collected du r ing 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 le vels 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 dow nstream of the S ite, 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. T he HRS does not require the timing of sample collection to coincide with rain events

. I n this situation , it woul d 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 HR S. 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 EP A 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.

3.1 6 .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 dir ect 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 c oncerns with background surface water samples for the Site re lated to the above text,

ARC asserted that

in reference to Comment 18 9 , 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 a nd the NCP can be prepared.

On a similar subject, Mr. Parkhill commented that ground water in the Morr ison 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 rive r water quality.

Response : To the extent that the commenter s w ere implying th at 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 th e 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 watersh ed. 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

a ppears 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 tha t 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 Com ponent: 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 sectio n 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 (an d 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 unlikelysource 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). Fi eld 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 componen t 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

- 110420 10 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 e valuated for the overland/flood migration component, the release sample s 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, th ese sample s 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 s urface

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 s ite 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 o ther 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 Inspecti on 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.

A RC 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 fo r 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 thatJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

54 i n reference to Comment 18 11 , 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 requ irements of the HRS, must be conducted before a HRS that meets the requirements of CERCLA a nd 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 minin g 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 amoun ts 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- commer cial 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 be cause the hazardous

substances – uranium and manganese

– are clearly related to the S ite 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 do cument, 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 compon ent 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 backg round 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

t he site sources; a description of the many mechanisms by which site

- related hazardous substances may have entered surface water; an explanation of why the signific ant 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:

• Adeq uacy of Background Samples

• HRS Documentation Record Reference 35 Conceptual Site Model Assessments

• Summary

Adequacy of Background Samples

Section 3.1 5, Likelihood of Release: Background and Significant Increase , of this support document, explains that th e 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, detail s 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 ac count for any uranium that would be added naturally to surface water – there is another significant increase

scale elevation in concentration at the next downstream sampling point. This indicates a strong

contribution of hazardous substances from the S ite 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 S ite 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 addresse s 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

t he 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 contaminat ion 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 co

mingled with the pre

- mi ning Alluvium, and efflorescent sediments that were deposited by evaporation with the Alluvium during the pre-mining era.

On page 2791 of Reference 35, t he ESI Revised Conceptual Site Model addressed uranium contributions from ground water to surface wate r:

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 urani um 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 Jack pile 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 ad ded]

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 b e 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 Jack pile 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 thi s 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 W eathered Jackpile Sandstone is an unlikely source of significant quantities of uranium in the surface water system . The weathering process would include physic al 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 significa nt 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

page s 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 201 1 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. Qual itative 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 efflor escent 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 fl ooding.

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 repre sents 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 th an 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

- m ining

- 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 S ite 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 S ite; 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 r equirement.

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):

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 is incorre ct 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 state s:

The primary source of uranium in surface and groundwater on

- site, an d down

gradient 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 decisi on t o place the Site on the

NPL.

3.1 6.5 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 evapo ration 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 reaso ns 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 S ite (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 elevat ion 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 contamina nt 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 S ite. The lower levels of uranium in this sample contradict a scenario in which e vaporation 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 3.1 6.1 , Ba ckground S amples 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

- SW

110420, 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 3.1 6.6 E ffects of Wind Deposition

Comment : ARC asserted that the EP A 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 wi th 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 eq ually 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 releas e from the S ite (and the HRS air migration pathway could have been evaluated in that case). On the other hand, i f the commenter is implying the origin of any wind- deposited contaminants is outside the S ite , 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 re vegeta tion 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

Do cumentation 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 contaminant s 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 obse rved 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: A ttribution, 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 c hange 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 arbitrar y, and must be reassigned.”

To support th is claim, ARC cited Chapter 4 of Sampling Strategies, EPA Guidance for P erforming 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:

backgrou nd 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 eve nts 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 o f 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:Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

62 • D irect 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, s ample 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 prese nt 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 woul d 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 t elephone conversation record

r egarding s ample l ocation 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 d irect 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 3.1 6, 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 th e 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 mandato ry requirements, and t he 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 t h e 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 vi cinity 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 commen ter 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 w atershed 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 S ite via overland flow.

HRS Section 4.1.1.2, Target distance limit , detail s 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 surf ace 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 contiguou s 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 obs erved 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 con centrations 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 c riteria 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.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

64 Page 32 of the HRS documentation record at proposal d escribes the Si te 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 proposal 12 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,

b ecause Source 1 is no longer evaluated for the overland/flood migration component

, probable points of ent ry (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 result ing target distance limit (TDL) has been reduced by approximately 1.1 miles to reflect this (as detailed on page 33 and Fig ure A

- 5A of th e HRS documentation record at promulgation). This minimal change has no e ffects 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 t he 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 down stream 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 i n 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

, Si te 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, determin e 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 F or 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 subjec t 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 th e 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 (P i ) 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 porti ons 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 esti mated 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 t o 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.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

67 • A ssign 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 (uranium 238 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,

uranium 234 , uranium 235 , and uranium 238 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 “fishin g 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 be lieve 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 t he 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 obse rved 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 identif ie s 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 :Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

68 The zone of Level II contamination in Rio Paguate extends 27,800 feet from samples

RM

- JM

- SW /SED and RP

- JM

- SW/SED 13 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 adde d]

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 (an d 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 Pueb lo 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 Mesi ta 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 s amples 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. 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 chan ge 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 distanc e 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 NP L 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 bioaccumu lation pathway for fish,

cattle and elk.” ARC contended th at t he “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 da ta is provided to support this risk; therefore, the “ EPA’s assertions are arbitrary and capricious, ” and the human food chain t hreat s core “ 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 associat ed 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

incl ude 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 foodJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

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 T able 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 T able 4 -16, based on the values assigned for the toxi city/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 T able 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

toxi city/persistence factor value and the hazardous waste quantity factor value for the watershed, subject to a maximum product of 1x10 8 . Then multiply this product by the bioaccumulation potential factor value for this hazardous substance, subject to a

maximu m product of 1x10 12 . 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 T able 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 t wo 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 t arget 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 e ntry 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. E nter this value in T able 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 f ood 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 v alue for the human food

chain threat using a bioaccumulation potential factor value from the hazardous substance with the highest toxicity/persistence/bioaccumulation factor value 14 :

Toxicity/Persistence Factor Value: 10,000 Hazardous Waste Quantity Facto r 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 10 10 (maximum of 1 x 10 8 according to HRS Section 4.1.3.2.3)

1 x 10 8 (Toxicity/Persistence Factor Value x Hazardous Waste Quantity Factor Value) x

14 As detailed in section 3.25.2, Human Food Chain Threat Waste Ch aracteristics, 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).Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

72 50,000 (Bioaccumulation Potential Factor Value) = 5 x 10 12 (maximum of 1 x 10 12
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 uranium 238 have a toxicity/persistence value of 10,000 and a bioaccumulation potential factor of 50,000 15

. The waste characteristics factor category value from Reference 1, Table 2

- 7 for a waste characteristics product of 1 x 10 12 is 1,000.

Hazardous Waste Qua ntity 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 limi t 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 o n 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 documen tation record, an observed release of hazardous substances having a bioaccumulation factor value of 500 or greater (uranium 238 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,

uranium 234 , uranium 235 , and uranium 238 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

identif ying 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 S ite:

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 drink ing 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 identifie s 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 identify ing 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

contamination 16 , 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 structu re 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 calcul ation 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 5x10 8 is incorrect and that this error

detracts from overall confidence in a ll 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 threa t- targets ).Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

74 Response : Based on this comment, t he 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 H RS 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

calculat ion 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 S ite 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 th e 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 g roundwater were not representative of background conditions for J ackpile 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 groundJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

75 water samples likely predominantly reflect the uranium from the Jackpile Sandstone (and its isotopic

si gnature) in waste materials that has been disturbed by mining processes and made mobile and available to ground water at and downgradient of the mine.

Th ese 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 requi ring that samples from one medium b e 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 th e 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):Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

76 -For radionuclides that occur naturally and for radionuclides that are ubiquitous in the

e nvironment:

-- 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 site

specific 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 concentration s; 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 state s 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

wa ter 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 wate r, 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 Mode l 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 identifyi ng ground water background uranium levels. The model

describe s 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 ura nium 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 inJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

77 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 tha t “[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) identifie s 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 Jackpil e 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 v alues 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 hydrolo gic system. Pre

remedial 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+

m illion 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 Aquife r 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 unlikelysource 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 res pect 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 diss olved 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 thro ugh 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 pro cesses 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 substant ial 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 n ot 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 theJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

79 water table and could not have been the source of Uranium or any other metals that were leached out of

t he 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 pit s have rebounded. And, i nasmuch 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 evalu ating 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 sub stances 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

wa ter 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, gr ound 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 anticipa ted. 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 Allu vial 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 theJackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

80 fa c ility. 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 increa sed 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 do es constitute a connection between water in the pits and surface water.

This comment resul ts 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 S ite, 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, t he 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 inves tigations.

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 aJackpile -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 wa ter, 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 o n 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 wat er 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 S ite 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 Al so
, 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.



### 3.2 4 Accuracy of the EPA Site Narrative

Comment : ARC dis agreed with several aspects of the EPA NPL Site Narrative for the Site, stating that it “contains statements that ARC believes are misleading, unsupported by t he 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 S ite, the information contained in the Site Narrative is

consistent with the information used in the HRS evaluat ion of the S ite. The following subsections address the consistency of the S ite N arrative with the HRS evaluation of the S ite:

• 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 “misleadi ng” 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 sim ilarly 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 Uraniu m.”

Response : T he 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 sur face 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 Uranium 234 4.858

5.073 1.077706361 7.228412721 RM

- SW

- BG

- 110419 Uranium 234 4.119

RP

- SW

- BG

- 041911 Uranium 234 6.242

MD

- SW

- 110420 Uranium 235 0.306

0.2072 0.103481013 0.414162026 RM

- SW

- BG

- 110419 Uranium 235 0.0996

RP

- SW

- BG

- 041911 Uranium 235 0.216

MD

- SW

- 110420 Uranium 238 2.811

2.94466667 0.790026793 4.524720252 RM

- SW

- BG

- 110419 Uranium 238 2.23

RP

- SW

- BG

- 041911 Uranium 238 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 c oncentration. Pages 39 -41 of the HRS documentation record at proposal show the release sample concentrations fromthe April 2011 SI; a summary is presented in the following table alongside the associated backgroundbased criteria:

Station Location Locatio n 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 Uranium 234

Uranium 235

Uranium 238 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 Uranium 234

Uranium 235

Uranium 238 28.334

0.961

23.591 7.228412721

0.414162026

4.524720252

RP

- JM

- SW

- 110420 19 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 Uranium 234

Uranium 235

Uranium 238 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, becau se Source 1 is no longer evaluated for the overland/flood migration component, the release sample s 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, th ese sample s 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 Locatio n 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 Uranium 234

Uranium 235

Uranium 238 32.398

1.236

29.257 7.228412721

0.414162026

4.524720252

RP

- SW

- 01

- 110420 Rio Paguate, 9,500 feet.

downstream of PPE4 20 Uranium 234

Uranium 235

Uranium 238 85.098

3.236

78.787 7.228412721

0.414162026

4.524720252

PR

- SW

- 01

- 110420 Paguate Reservoir, 22,300 feet

downstream of PPE4 Uranium 234

Uranium 235

Uranium 238 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

t he mean background concentration, but often exceed it: U- 234 release concentrations are approximately

2 to 12 times the observed release criteria valu e; 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 documentati on rec ord 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 concentration s 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 chang e 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 backgr ound levels and establishment o f 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),

a nd has been corrected in the HRS documentation record at promulgation.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

85 A RC 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 wi th the Jackpile Mine site.”

Response : The information presented in the HRS package at proposal regarding ongoing releases from the

S ite is sufficient to document that releases have occurred after any reclamation activities. Given that site

conditions h ave 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 S ite . A s explained on pages 7-9 of the HRS documentation record a t 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).

T he 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 wa ter 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 n othing 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 ura nium 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 • A s 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: Attrib ution, of this support document and its subsections, some portion of th e 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 th an 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 t raditional/ c ultural 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 R eference 42 of the HRS documentation record at promulgation (a memorandum from Curtis L. Francisco of the Pueblo of Laguna Environmental and Natural Resou rces Department ) contain statement s 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 Narra tive 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 (poi nting 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 : T he majority of the substances listed in the EPA Site Narrative are associated with the S ite based on data presented in the HRS documentation record at proposal and associated references

. A lthough 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

establishe s that these hazardous substances are available to migrate to the surface water pathway from

these sources because the contai n ment featur es 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.

Th ese comments on the EPA Site Narrative resultin 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,

a fter 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 e ffects 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

evaluat ion 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 haz ardous 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.

Howeve r, 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 2 1 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 categ or y 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/pe rsistence factor value , states to:

Assign each hazardous substance a toxicity/persistence factor value from T able 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

Pers istence 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 Persistence 1

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

Uranium 234 2 10,000 1 10,000 Ref. 2, p. 16

Uranium 235 2 10,000 1 10,000 Ref. 2, p. 16

Uranium 238 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 th at 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 quanti ty 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 (incl uding 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 Se ction 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 T able 2 –6.

Table 2 –6— Hazardous Waste Quantity Fact or Values

Hazardous waste quantity value Assigned value

0 0

1 a to 100 1 b

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 T able 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 T able 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 T able 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 T able 2 –6 with and without consideration of the

removal action.

- If the value that would be assigned from T able 2 –6 without consideration of the removal action would be 100 or greater, assign either the value from Ta ble 2 –6Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

90 with consideration of the removal action or a value of 100, whichever is

g reater, as the hazardous waste quantity factor value for the pathway.

- If the value that would be assigned from T able 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/persiste nce and hazardous waste quantity factor values for the watershed, subject to a maximum product of 1×10 8 . Based on this product, assign a value

from T able 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 1×10 2 2

1×10 2 to less than 1×10 3 3

1×10 3 to less than 1×10 4 6

1×10 4 to less than 1×10 5 10

1×10 5 to less than 1×10 6 18

1×10 6 to less than 1×10 7 32

1×10 7 to less than 1×10 8 56

1×10 8 to less than 1×10 9 100

1×10 9 to less than 1×10 10 180

1×10 10 to less than 1×10 11 320

1×10 11 to less than 1×10 12 560

1×10 12 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 10 8 . 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 result s in no change to the drinking water threat waste characteristics factor category valu e; and with respect to this factor category value, there is no change in the S ite score or the decision to place the Site on the NPL.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

91 3.25.2 H uman Food Chain Threat Waste Characteristics

As explained in s ection 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/bioaccumul ation 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 val ue 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 Persistence 1

Factor

Value Human Food
Chain

Bioaccumulation 2

Value Toxicity/

Persistence/

Bioaccumulation

Factor Value Reference

Manganese 2 10,000 1 50,000 5 x 10 8 Ref. 2, p. 10

Vanadium 2 100 1 500 5 x 10 4 Ref. 2, p. 13

Uranium 234 2 10,000 1 0.5 5,000 Ref. 2, p. 16

Uranium 235 2 10,000 1 0.5 5,000 Ref. 2, p. 16

Uranium 238 2 10,000 1 5,000 5 x 10 7 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 10 8

, based on manganese.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

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 fact or value and the hazardous waste quantity factor value for the watershed, subject to a maximum product of 1×10 8 . Then multiply this product by the bioaccumulation potential factor value for this hazardous substance, subject to a maximum product of 1×10 12

. 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 chai n 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

Bio accumulation Potential Factor Value: 50,000

10,000 (Toxicity/Persistence Factor Value) x 10,000 (Hazardous Waste Quantity Factor Value) =

1 x 10 8 (maximum of 1 x 10 8 according to HRS Section 4.1.3.2.3)

1 x 10 8 (Toxicity/Persistence Factor Value x Hazardo us Waste Quantity Factor Value) x 50,000 (Bioaccumulation Potential Factor Value) = 5 x 10 12 (maximum of 1 x 10 12 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 Ref erence 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 10 12 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 va lue and no change to the

S ite score or the decision to place the Site on the NPL.Jackpile -Paguate Uranium Mine NPL Listing Support Document December 2013

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. T he final scores for the Jackpile

- Paguate Uranium Mine site are:

Ground Water Migration Pathway: Not scored

Surface WaterMigration Pathway: 100.00 Soil Exposure Pathway : Not scored

Air Migration Pathway: Not scored

HRS Score: 50.00