Preassessment Screen and Determination: Rio Algom Mines and Quivira Mill Site, McKinley County, New Mexico New Mexico Office of Natural Resources Trustee Albuquerque, New Mexico September 2010 Contents List of Figures..............................................................................................................................iv List of Tables................................................................................................................................v List of Acronyms and Abbreviations........................................................................................vi Chapter 1 Introduction......................................................................................................1-1 1.1 Intent of the Preassessment Screen....................................................................1-1 1.2 Criteria to Be Addressed by the Preassessment Screen.....................................1-2 Chapter 2 Information on the Site [43 CFR § 11.24]......................................................2-1 2.1 Location and Description...................................................................................2-1 2.2 Site History and Mining Process.......................................................................2-4 2.3 Identification of Potentially Responsible Parties...............................................2-8 2.4 Releases of Hazardous Substances....................................................................2-9 2.4.1 Hazardous substances released..............................................................2-9 2.4.2 Sources of hazardous substance releases...............................................2-9 2.4.3 Time, quantity, duration, and frequency of releases............................2-11 2.5 Relevant Operations Occurring at or near the Site..........................................2-12 2.6 Damages Excluded from Liability...................................................................2-12 Chapter 3 Preliminary Identification of Resources at Risk [43 CFR § 11.25].............3-1 3.1 Preliminary Pathway Identification [43 CFR § 11.25(a)]..................................3-1 3.1.1 Pathways to groundwater.......................................................................3-1 3.1.2 Pathways to surface water/sediment......................................................3-3 3.1.3 Pathways to soils....................................................................................3-3 3.1.4 Pathways to vegetation and biota...........................................................3-3 3.2 Exposed Areas and Estimates of Concentrations [43 CFR § 11.25(b)].............3-4 3.2.1 Groundwater..........................................................................................3-4 3.2.2 Surface water.........................................................................................3-9 3.2.3 Terrestrial resources.............................................................................3-12 3.3 Potentially Affected Resources [43 CFR § 11.25 (e)(1)]................................3-17 3.4 Preliminary Estimate of Potentially Affected Services [43 CFR § 11.25(e)(2)]....................................................................................3-17 Page ii Contents (9/2010) Chapter 4 Determination Criteria [43 CFR § 11.23(e)].................................................4-1 4.1 A Release of Hazardous Substances Has Occurred...........................................4-1 4.2 Trust Natural Resources Have Been Adversely Affected by the Release.........4-1 4.3 The Quantity and Concentration of the Released Hazardous Substances Are Sufficient to Potentially Cause Injury.........................................................4-2 4.3.1 Groundwater..........................................................................................4-2 4.3.2 Surface water.........................................................................................4-8 4.3.3 Terrestrial resources...............................................................................4-9 4.4 Data Sufficient to Pursue an Assessment Are Available or Likely to be Obtained at Reasonable Cost...........................................................................4-11 4.5 Response Actions Will Not Sufficiently Remedy the Injury to Natural Resources without Further Action...................................................................4-11 4.6 Conclusions......................................................................................................4-12 References.................................................................................................................................R-1 Page iii Figures 2.1 Site overview.................................................................................................................2-2 2.2 Underground mine workings.........................................................................................2-3 3.1 Preliminary identification of pathways by which State resources may be exposed to hazardous substances from the Site.............................................................3-2 3.2 Geologic cross-section at the Site..................................................................................3-5 3.3 Uranium deposits in the Morrison Formation................................................................3-6 3.4 Uranium concentrations in Sections 19, 24, and 35 mine shafts from the early 1960s to 2005........................................................................................................3-8 3.5 Sulfate concentrations in alluvial wells at the Site and estimated areal extent of saturated alluvium for different parts of the Site.....................................................3-10 3.6 Areas where mining activities have potentially impacted soils at the Site..................3-13 4.1 Uranium exceedences in bedrock groundwater near the Site in western, central, and eastern portions of the bedrock groundwater.............................................4-4 Page iv Tables 2.1 History of the Site..........................................................................................................2-4 2.2 Hazardous substances and other constituents of concern in mine process liquids and tailings liquids.......................................................................................................2-10 3.1 Summary of geologic characteristics.............................................................................3-7 3.2 Mean concentrations of sulfate, uranium, radium-226, and selenium in deep groundwater in section mines, 1958 to 2005.................................................................3-8 3.3 Contaminant concentrations in alluvial groundwater....................................................3-9 3.4 Water quality in the Arroyo del Puerto, 1980..............................................................3-11 3.5 Average concentrations of radioactive constituents in sediment from former evaporation ponds, tailings, and areas with windblown tailings.....................3-14 3.6 Concentrations of radium and uranium in soil leachate (water percolated through soils) from east of the former Section 4 Ponds............................................................3-15 3.7 Concentrations of arsenic, molybdenum, and selenium in soil leachate (water percolated through soils) from east of the former Section 4 Ponds.............................3-16 3.8 Concentrations of radium, uranium, and arsenic in soils from east of the former Section 4 Ponds................................................................................................3-16 3.9 Concentrations of molybdenum, selenium, and vanadium in soils from east of the former Section 4 Ponds......................................................................................3-16 4.1 State of New Mexico and federal water quality standards used to evaluate potential groundwater injury..........................................................................................4-3 4.2 Comparison of mean concentrations of sulfate, uranium, radium-226, and selenium for Ambrosia Lake uranium mines, 1958 to 2005, to water quality standards............................................................................................................4-3 4.3 Comparison of contaminant concentrations in alluvial groundwater to water quality standards............................................................................................................4-5 4.4 Historic Westwater Canyon member analytical results (µg/L).....................................4-6 4.5 Concentrations of selected contaminants in the Section 32 Mine shaft and the Section 23 well...............................................................................................................4-7 4.6 Soil benchmark or screening level concentrations for the protection of plants, biota, and groundwater.....................................................................................4-10 Page v Acronyms and Abbreviations ACL alternate concentration limit ALC aquatic life criteria CERCLA Comprehensive Environmental Response, Compensation, and Liability Act cfs cubic feet per second cm centimeter cpm counts per minute CWA Clean Water Act DAF dilution/attenuation factor DOE U.S. Department of Energy DOI U.S. Department of the Interior Eco-SSL ecological screening level FIFRA Federal Insecticide, Fungicide, and Rodenticide Act ft feet gpm gallons per minute µg/L micrograms per liter µR/hr micro-Roentgens per hour MCL maximum contaminant level mg/kg milligrams per kilogram mg/L milligrams per liter NaCl sodium chloride NaClO sodium chlorate 3 Na U O sodium diuranate 2 2 7 (NH ) U O ammonium diuranate 4 2 2 7 NMED New Mexico Environment Department NRC Nuclear Regulatory Commission NRDA natural resource damage assessment ONRT Office of Natural Resources Trustee pCi/µg picocuries per microgram pCi/g picocuries per gram pCi/L picocuries per liter PMP probable maximum precipitation PRP potentially responsible party QMC Quivira Mining Company RCRA Resource Conservation and Recovery Act Page vi Acronyms and Abbreviations (9/2010) SDWA Safe Drinking Water Act SMCL secondary maximum contaminant level SO sulfate 4 SSL soil screening level s.u. standard units TDS total dissolved solids TI tailings impoundment UNC United Nuclear Corporation U.S. EPA U.S. Environmental Protection Agency USFWS U.S. Fish and Wildlife Service Page vii 1. Introduction Hazardous substances1 have been released to the environment as a result of mining and milling activities at uranium mines and the Quivira Mill owned by Rio Algom Mining Ltd. (the Site) in McKinley County, New Mexico. Specifically, the Site includes nine section mines and associated facilities owned by Rio Algom that are located north of the mill area and the Quivira Mill. The State of New Mexico (the State) Office of Natural Resources Trustee (ONRT) has begun the process of assessing natural resource damages at the site in accordance with the natural resource damage assessment (NRDA) regulations promulgated by the U.S. Department of the Interior (DOI) at 43 CFR Part 11 (hereafter, the DOI regulations). These regulations are not mandatory. However, assessments performed in compliance with these regulations have the force and effect of a rebuttable presumption in any administrative or judicial proceeding under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) [42 U.S.C. § 9607(f)(2)(C)]. The first step in the process established by the DOI regulations is the preparation of a preassessment screen. 1.1 Intent of the Preassessment Screen The purpose of a preassessment screen is to determine whether a discharge or release of a hazardous substance warrants conducting a NRDA. It is intended to be based on “a rapid review of readily available information . . . [to] ensure that there is a reasonable probability of making a successful claim” [43 CFR § 11.23(b)]. A preassessment screen is not intended to serve as a completed assessment of natural resources injuries or damages. To prepare this preassessment screen, ONRT relied largely on existing data and engineering reports developed for the Site (e.g., AVM Environmental Services and Applied Hydrology Associates, 2000; Maxim Technologies, 2001; INTERA, 2007). All literature and data sources relied on in the preparation of this preassessment screen are presented in the references provided at the end of this report. 1. The term “hazardous substance” refers to a hazardous substance as defined in Section 101(14) of CERCLA [43 CFR § 11.14(u)]. This includes hazardous substances designated or listed by Sections 311(b)(2)(A) and 307(a) of the Federal Water Pollution Control Act (a.k.a. the Clean Water Act, or CWA), by Section 102 of CERCLA, by Section 3001 of the Solid Waste Disposal Act (a.k.a. the Resource Conservation and Recovery Act, or RCRA), or listed by Section 112 of the Clean Air Act. Page 1-1 Introduction (9/2010) 1.2 Criteria to Be Addressed by the Preassessment Screen The content and requirements of a preassessment screen are described at 43 CFR § 11.23. As described in the regulations, the State evaluated whether the following criteria have been met [43 CFR § 11.23(e)]: 1. A release of a hazardous substance has occurred. This criterion was evaluated by reviewing information on sources of hazardous substances, evidence of releases of hazardous substances to the environment, and data demonstrating elevated concentrations of hazardous substances in natural resources. 2. Natural resources for which the State may assert trusteeship have been or are likely to have been adversely affected by the release. This criterion was evaluated by reviewing data on the magnitude of natural resources exposure to hazardous substances relative to potential adverse effect thresholds. 3. The quantity and concentration of the released hazardous substance are sufficient to potentially cause injury to those natural resources. This criterion was evaluated by comparing concentrations of hazardous substances in surface water and groundwater to regulatory criteria, and by comparing concentrations of hazardous substances in geologic resources to potential injury thresholds. 4. Data sufficient to pursue an assessment are readily available or likely to be obtained at reasonable cost. Reasonable cost is defined in the DOI regulations as meaning that “the Injury Determination, Quantification, and Damage Determination phases have a well-defined relationship to one another and are coordinated . . . and the anticipated cost of the assessment is expected to be less that the anticipated damage amount” [43 CFR § 11.14 (ee)]. Although the specific elements of injury determination, quantification, and damage determination have not yet been developed for this Site, ONRT does not anticipate difficulties in developing a well-defined and coordinated process. Further, monitoring data for groundwater and other natural resources already exist for the Site, and more data are being collected as part of remedial planning and response activities. ONRT believes that additional data collection for groundwater and other trust resources could be conducted at reasonable cost, as defined in the regulations. 5. Response actions carried out or planned will not sufficiently remedy the injury to natural resources without further action. Response actions over the past 25+ years include covering and capping of tailings impoundments (TIs; AVM Environmental Services and Applied Hydrology Associates, 2000), reclamation and revegetation of some evaporation ponds (Brummett et al., 2006), construction of interceptor trenches to intercept contaminated groundwater, and pumping of contaminated groundwater (Rio Page 1-2 Introduction (9/2010) Algom Mining, 2007). Despite these efforts, concentrations of hazardous substances continue to exceed injury thresholds in some natural resources, sometimes by orders of magnitude. Additional reclamation and remediation actions have been proposed. Absent the complete removal of contaminated mine and mill waste and the extraction and treatment of contaminated groundwater, it is likely that areas of the Site will remain sources of hazardous substances to State resources for many years. Moreover, none of these remedies will address past and ongoing injuries to natural resources. As described in greater detail below, the State has concluded that the determination criteria outlined in the DOI regulations have been satisfied, and therefore the State intends to proceed with further NRDA activities at the Site. Page 1-3