memo - pinto valley mine eis• mwmp characterization per astm method e2242 (astm, 2012), with...

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MY/CH/JR TSF3-TSF4_Char_215900-290_20160504_jr_ckh_FNL.docx May 2016

Memo To: Mr. Timothy S. Ralston, CHMM, REM Date: May 4, 2016

Company: Pinto Valley Mining Corp. From: C. Hoag, J. Rasmussen, D. Bird, M. York, C. Kelley, R. Peroor

Copy to: Chris Rife, WestLand Resources, Inc. Project #: 219500.290 Task 500

Subject: TSF3 and TSF4 Tailings Characterization and Reclamation Strategies

1 Introduction This technical memorandum provides tailings characterization information for Tailings Storage Facility No. 3 (TSF3) and Tailings Storage Facility No. 4 (TSF4) at Pinto Valley Mine (PVM) shown on Figure 1, including:

• a summary of static and kinetic geochemical testwork completed on existing tailings from TSF3, TSF4, and metallurgical test tailings that represent future tailings material;

• a description of surface preparation measures, if any, that would be conducted prior to placement of tailings (e.g. pre-sliming) based on existing design data and reports by Amec Foster Wheeler (AFW);

• a description of soil stockpiling, if any, prior to placement of tailings, and • a description of the BADCT measures in place and proposed; and • other environmental protection measures applicable to the TSFs.

This document also summarizes the current reclamation strategies for TSF3 and TSF4 based on information previously prepared by Amec (i.e. reclamation design, post-closure drainage design) and by PVMC and SRK Consulting (SRK) (i.e. Mined Land Reclamation Plan (MLRP)), Closure and Post-Closure Strategy, Aquifer Protection Permit (APP) application materials, and seed mix recommendations).

2 Sample Materials and Collection Methods The challenge in characterizing active TSFs is to collect representative materials that accurately reflect the lateral and vertical variability found in a large tailings facility, especially if changes over time have occurred in ore host rocks or mineral types within the deposit, grind size of the processed ore, or tailings construction methods. Tailings used to construct the starter dam and embankment structures typically contain dominantly coarser, free-draining sand-size constituents and constitute a zone of active oxidation and oxygen ingress; a continuous air phase is present in the embankment skin and at the surface of the tailings pond. Finer silt- or clay-size materials (slimes) are deposited in the beach area in back of the dam crest and in the area of the supernatant pond. Tailings at the toe of an embankment represent older tailings that have been exposed to oxygen for a longer period, may also have been exposed to water erosion, and are likely to be more oxidized than the relatively fresh tailings recently deposited at the dam crest or the saturated tailings submerged at depth with no continuous air phase present and limited oxygen. Heterogeneities in layers of finer and coarser material within a tailings may also affect water movement through the tailings and the circulation of oxygen. During draindown of a tailings facility at closure, oxygen entry is controlled by (1) advection of oxygen in water that infiltrates into the tailings surface or through cracks from surface to deeper

SRK Consulting Pinto Valley TSF3 and TSF4 Characterization


levels, (2) diffusion of oxygen in water through pore spaces in the tailings that remain water-saturated, and (3) diffusion of oxygen in air through unsaturated void spaces in the tailings.

During site characterization activities at an active TSF, surface samples are easily collected with a shovel or shallow test pit along access roads on the dam crest or embankment face, or in drier perimeter or beach areas. Samples from greater depths are collected by auger or sonic drilling along dam crest roads or in beach locations within the TSF or in perimeter areas. The beach areas, however, are more difficult to access owing to the consistency of newly deposited tailings and potential unstable conditions for excavation or drilling equipment. The preponderance of surface samples therefore creates a bias in sample results towards the coarser and potentially more weathered/oxidized samples. Deep samples are more representative of the total volume of tailings in the facilities, but are typically under-represented relative to the larger numbers of shallow samples.

The shallow surface samples represent the tailings that have been exposed to oxygen concentrations typical of surface conditions (~20.9%) while oxygen concentration decreases rapidly with depth below the surface and laterally away from the embankment face. Oxygen monitoring by SRK at similar (but closed and drained) TSFs in southern Arizona confirmed that oxygen concentrations are reduced to only 3-5% at depths of 85-100 feet below surface.

The characterization samples collected at PVM are predominantly shallow samples of less than 2 feet in depth located along embankment faces and dam crests. Samples representing finer and coarser materials have also been collected for testing directly at the mill during processing. Although there are fewer tailings samples located in the internal and perimeter beach areas and at depth, there are sufficient results to provide an indication of geochemical characteristics of the various types of existing tailings materials. In 2015-2016, tailings from metallurgical test work were analyzed to characterize the geochemical characteristics of representative future tailings at PVM.

2.1 Historic Sampling

Geochemical characterization of TSF3 and TSF4 was performed in 1995 as part of site characterization studies required under the Aquifer Protection Permit (APP) program (Schafer and Associates, 1995). Additional characterization was performed in 2004 by MWH (MWH, 2005) to support closure-related studies. Characterization samples were also collected by Water Management Consultants (WMC), now Schlumberger Water Services (SWS), in 2009.

Schafer and Associates (1995) collected primarily test pit samples (TP labels). Six samples were collected from tailings material slimes located on top of TSF3 and six from TSF4. Six samples were collected from cyclone tailings material deposited along the top of TSF3 dam and six from the top of the TSF4 dam (Figure 2 and Figure 3). Grab samples were collected from test pits that were approximately a 6- to 18-inch depth and that consisted of both embankment materials (cyclone sands) (TP3C-1 through TP3C-6 for TSF3 and TP4C-1 through TP4C-6 for TSF4) and slimes (TP3-1 through TP3-6 for TSF3 and TP4-1 through TP4-6 for TSF4). Slimes samples were collected from the drier area around the pond perimeters.

MWH (2005, 2006) collected samples at various depths below the tailings surface (Figure 4 and Figure 5). These sample depths included 0-12” by surface sampling (SS sample numbers), 0-10 ft by auger boring (AH sample numbers), 30-40 ft by percussion hammer drilling (DH sample numbers), and at various depths by sonic drilling chips. Materials collected include sand, silty sand, and silt. Sample locations, especially for TSF4 beach samples, have been buried by subsequent deposition of tailings in the 12 years since the sample collection dates in 2004. MWH surface samples include SS04-T3-34 through SS04-T3-41 for TSF3 and SS04-T4-47 through SS04-T4-60 for TSF4. MWH AH sample numbers include AH04-T3-15P and AH04-T3-17P for TSF3 and AH04-T4-22P and AH04-T4-23P for TSF4. Samples from percussion hammer drilling include DH sample numbers DH04-T4-25P and DH04-T4-27P for TSF4. The sample sent for the MWH (2005) HCT was AH04-T4-24 from TSF4.

SWS samples were collected from sonic drilling chips in 2008 including samples TD 308-1 through TD 308-4 samples for TSF4. These sample numbers include tailings embankment samples TE3-1 through TE3-3 from TSF3 (SWS, 2009 data).

SRK Consulting Pinto Valley Tailings Static Analyses

MY/CH/DB TSF3-TSF4_Char_215900-290_20160504_jr_ckh_FNL.docx May 2016

The locations of test pit sample locations from TSF3 and TSF4 are presented in Figure 2 and Figure 3, respectively. Shallow surface samples from TSF3 and TSF4 are presented in Figure 4 and Figure 5, respectively. The locations of selected samples are not available based on a review of historic reports.

2.2 2015 Sampling

Two ore-bearing composite samples representing future phases of mining at PVM were processed in 2014 and 2015 during a metallurgical testwork program performed by Capstone Mining Corp. Twenty-nine samples from 21 drill holes were sent to Base Metallurgical Laboratories Ltd. (BaseMet) in Kamloops, B.C., Canada. Tailings from this metallurgical testing were provided to ACZ Laboratories (ACZ) of Steamboat Springs, Colorado, under the direction of SRK for static and kinetic testwork.

These metallurgical test residue samples represent potential future tailings to be deposited predominantly on TSF4 from approximately year 2026 through the end of processing and tailings deposition in 2039 (referred to as Pinto Valley Phase 3 or PV3). Although these metallurgical test tailings have not been exposed to several years of weathering as have actual tailings, they do represent a composite of tailings to be generated in the future and provide an indication of expected geochemical behavior.

Twenty-five drill core samples were from the Precambrian Ruin Granite, which is locally called quartz monzonite porphyry (QMP) in the deposit area and which is the dominant future PVM ore host. Four samples were from aplite, a secondary ore type present during the PV3 phase of operations. The samples were obtained from representative diamond drill core penetrating the pit pushback phases in the PV3 mine plan at various elevations. They were designated as Eastern Pushback “Lower-Level Length”, “Mid-Level Length”, and “Upper-Level Length samples and the Northern Pushback “Lower-Level Length”, and Mid-Level Length” samples (Table 1 and Table 2). The representative material was collected from PVM diamond drill core based on intervals selected by Capstone Mining Corp. (AJAX, 2014). Sample and drillhole locations for the composite ore samples are provided on Figure 6 (Base Metallurgical Laboratories, 2015). ACZ completed static testwork in January 2015 and the metallurgical test tailings samples were then composited for kinetic testwork, which took a year to complete.

3 Geochemical Testing Methods The characterization work performed on PVM tailings includes paste pH, acid base accounting (ABA), total metals, Synthetic Precipitation Leaching Procedure (SPLP) testing, and/or Meteoric Water Mobility Procedure (MWMP) testing, mineralogy, and humidity cell testing (HCT).

The geochemical analysis methods are based on industry best practice and on the geochemical screening guidance for evaluating behavior of mining waste materials as provided by Arizona Department of Environmental Quality (ADEQ) in Appendix B – Solution, Ore and Waste Characterization of Arizona Mining Guidance Manual – Best Available Demonstrated Control Technology (BADCT) (ADEQ, 2004a; 2004b). Analysis of the tailings material included the following tests, which are described in the following subsections:

• Acid-base accounting (ABA), including sulfur mineral speciation (total sulfur, sulfide sulfur, sulfate sulfur, and organic), acid neutralization potential, and paste pH;

• Net acid generation (NAG) test; • Whole rock geochemistry by ICP/ICP-MS analyses, to obtain total elemental composition of

each sample; • MWMP characterization per ASTM method E2242 (ASTM, 2012), with analysis of the MWMP

leachate for a suite of metals, anions, and pH; • SPLP testing per EPA Method 1312 (EPA, 1994) / ASTM method D6234-98 (ASTM, 1998); • Mineralogy by a combination of optical petrography, powder x-ray diffraction, and scanning

electron microprobe analyses; and/or



• Humidity Cell Tests (HCT) per ASTM method D5744 (ASTM, 2007). A brief summary of the testing methods is provided below for reader convenience.

3.1.1 Acid-Base Accounting Methods

ABA analysis is the procedure used to predict the potential for mine tailings or waste rock to generate acid rock drainage (ARD) owing to sulfide oxidation. ABA is an ADEQ-recommended Tier 1 screening level test (2004b). ABA determines the quantities of available sulfidic sulfur that can generate acid drainage, balanced against the quantities of carbonates and other minerals that can neutralize the acid production. ABA testing follows the method of EPA M600/2-78-54 (1.3, 3.2.2, 3.2.4). Coupled with other test results and the site mineralogy, ABA results provide an indication as to whether the material might generate alkaline, near neutral, or acidic drainage.

Long-term acid generating potential (AP) of the rock was assessed on pulps from the representative tailings samples. The AP in the rock is a function of the amount of sulfur present in the form of sulfide. To isolate the proportion of sulfide sulfur within the rock, the samples were analyzed for all forms of sulfur, including organic sulfur, sulfide sulfur, sulfate sulfur, and total sulfur. The AP of the sample was calculated on the basis of the sulfide sulfur content and expressed as [AP=%S- x 31.25] and reported in equivalent units (kg CaCO3/metric ton).

Neutralizing Potential (NP) is a function of the amount of carbonate and other minerals in the rock that have the capacity to neutralize acid. Several different standardized laboratory methods are used globally to determine NP depending on the regulatory structure. For this investigation SRK specified the modified Sobek method (Lawrence et al., 1989), which is a modification of the original Sobek method M600/2-78-054, 3.2.3 (, Sobek et al., 1978). Ground rock pulp is mixed with a known amount of de-ionized water and a known amount of acid is added to decrease the pH to approximately 2. The sample is then titrated with sodium hydroxide to a pH of 8.3. The amount of acid available to be neutralized in the original sample is then calculated.

A comparison of the NP to the AP of a sample provides an indication of the potential for the samples to generate acid over time. The difference between the two (NP minus AP) is the net neutralization potential (NNP), expressed in terms of equivalent kg CaCO3 per metric ton of material.

Arizona BADCT Guidance specifies the interpretation of NP and AP values as follows:

• If NNP is less than -20, the rock can be considered acid generating; • If NNP is greater than +20 the rock can generally be considered non-acid generating; and • Samples that fall between -20 and +20 are considered uncertain, and may be tested further

using kinetic testing methods the additional would be expected to assist in the design of the facility, i.e., design of ARD controls.

Arizona BADCT guidance also allows use of the neutralization potential ratio (NPR), calculated as NP ÷ AP, to assess acid generating potential. The criteria are as follows:

• NPR > 3 indicates low risk for acid drainage to develop; • NPR < 1 indicates that the rock is “more likely to generate acid”; • NPR between 1 and 3 indicate uncertainty and additional testing is usually necessary using

kinetic test methods described under Tier #2 protocols.

Another commonly used analytical procedure for estimating acid generating potential is the Net Acid Generation (NAG) Test (IWARK and EGi, 2002). The NAG test involves reaction of a sample with a 15% hydrogen peroxide (H2O2) solution to rapidly oxidize any sulfide minerals contained in the sample. During the test, acid generating and acid neutralizing reactions can occur simultaneously, and the end result is a direct measurement of the net amount of acid generated by the rock sample. The test uses 2.5 g of pulverized sample in 250 mL of hydrogen peroxide solution.



3.1.2 Total Metals Methods

The purpose of total element analyses is to provide data for calculating mass balance and for determining metal loading and long-term leaching behavior of the tailings. Total element analysis is an ADEQ-recommended Tier 2 geochemical test procedure.

Samples were analyzed for elements using EPA-approved methods of total element analysis by acid digestion (hydrofluoric acid-perchloric acid-nitric acid), coupled with Inductively Coupled Plasma (ICP), ICP-Mass Spectrometry (ICP-MS), Cold Vapor Atomic Absorption (CVAA), and Atomic Absorption (AA) analysis. Method detection limits and practical quantification limits are variable depending on constituent.

Sample results were then compared against Arizona Non-residential Soil Remediation Levels (NRSRLs), Arizona Groundwater Protection Levels (GPLs) (described in greater detail below), and Global Abundance values for crustal rock and soil materials. Global abundance data are from Reimann and Caritat (1998).

Soil remediation requirements under Arizona Administrative Code (A.A.C.) R18-7-206 states that any concentration of contaminants remaining in the soil after remediation must not cause or threaten to cause a violation of the Arizona Aquifer Water Quality Standards (AWQS). To evaluate the potential of groundwater impact from impacted soils, ADEQ has developed screening criteria termed the minimum GPLs, which are compared to total soil concentrations. The GPLs are published in the Screening Method to Determine Soil Concentrations Protective of Groundwater Quality (ADEQ, 1996). They are characterized in the guidance document as being a worst case, theoretical correlation between total metals concentrations in soils and the concentration of the leachable fraction of the metals from those soils. Therefore, soils having concentrations of metals below the minimum GPLs would not be expected to leach contaminants at concentrations that would impact groundwater above AWQS.

3.1.3 SPLP Test Method

SPLP is an industry-standard, ADEQ-approved Tier 1 test protocol (ASTM method D6234; EPA method 1312) for leachate testing that is performed on the material to determine the leachate water quality of samples under current conditions. Because these materials have undergone natural weathering, these materials were tested to evaluate potential runoff/infiltration water quality from the dumps.

This short-term extraction procedure is designed to determine the mobility of constituents due to leaching, and the test is commonly applied to estimating leachate quality of mine rock after meteoric water comes in contact with the rock. Constituents mobilized by the SPLP extraction will primarily be associated with secondary salts and other similar species analogous to what would be mobilized in the early stages of sequential extraction procedures.

EPA Method 1312 method calls for analysis of the solids for total metals and treatment of the solids with a weak sulfuric and nitric acid rinse. The rinse has a pH of 5.0 to simulate natural precipitation and a water-to-rock ratio of 20:1. This method provides an indication of short-term leaching (18±2 hours) of soluble constituents and readily dissolvable constituents from dried mined materials. The solids are screened to be less than 9.5 mm (0.4 in); reducing the grain size may increase the reactivity. SPLPs are not kinetic tests. Short-term leach tests, such as SPLP, provide limited information on long-term conditions (such as depletion of carbonate minerals and resulting acidification over time) and may underestimate leachability and resulting concentrations owing to high solution to solid ratio.

3.1.4 MWMP Test Method

MWMP is an industry standard, ADEQ-approved Tier 1 test protocol (ASTM, 2012) that is a short-term extraction procedure designed to predict the mobility of readily leachable minerals (e.g., soluble, reactive, and secondary minerals) when meteoric water comes in contact with the rock. MWMP was used to estimate the mobility of leachable constituents from the samples. When



compared to whole rock chemistry and mineralogy, these results identify potential controls on the leaching rates.

MWMP extracts are laboratory leachates that have no applicable regulatory standards in Arizona, but various numeric standards can be used for reference purposes to provide an approximate indication of potential water quality of seepage and/or runoff. The test method has not been demonstrated to simulate actual site leaching conditions, but may be used to support estimates of pH and mobility of soluble constituents from a rock sample. Solute mobilization resulting from meteoric contact with actual tailings may differ from that generated in the laboratory owing to differences in water-rock ratio, contact time, and attenuation processes.

The MWMP and SPLP are both short-term leach tests, but with key differences as follows: 1) The SPLP extract solution pH is 5.0 while the MWMP uses type II reagent grade water that has unspecified pH (ASTM, 1999) but typically ranges from 5.5 to 6.0; 2) particle size in the SPLP is specified as -9.5 mm versus -5 cm in the MWMP; 3) test duration for the SPLP is 18 hours versus 24 for the MWMP; and 4) the SPLP is a bottle roll while the MWMP is a column percolation test.

The primary advantage of the MWMP and SPLP are that they provide a screening level estimate of dissolution and mobility using a short-term and relatively inexpensive laboratory test that can be performed on larger numbers of samples than is done with long-term kinetic tests. The primary disadvantage is that they cannot provide information on long-term mineral reaction/oxidation rates including sulfide oxidation.

3.1.5 Humidity Cell Testing Method

The primary objective of an HCT is to accelerate the natural weathering of a solid material sample so that diagnostic mineral dissolution data are developed, and dissolution products are collected and analyzed. The principal data obtained from the humidity cell tests are mineral reaction rates and water quality of leachate that gives a preliminary indication of field leachate quality.

The humidity cell method involves weekly leaching of the sample with one liter of solution, with weekly collection and chemical characterization of the leachate. The test protocol was specified to involve weekly analysis of pH, conductivity, acidity, alkalinity, carbon, iron, and sulfate. Every four weeks, a more comprehensive analysis was performed that included the following, in addition to the weekly cycle analytes: antimony, aluminum, arsenic, barium, beryllium, cadmium, calcium, chloride, chromium, cobalt, copper, fluoride, iron, lead, lithium, magnesium, manganese, mercury, molybdenum, nickel, nitrate + nitrite, phosphorus, potassium, selenium, silicon, silver, sodium, strontium, sulfate, thallium, uranium, vanadium, and zinc.

A 26-week HCT was performed on fresh tailings from TSF4 by MWH (2006).

A 53-week HCT (10 February 2015 to 16 February 2016) was conducted on metallurgical test tailings representing future tailings at PVM. The 2015 HCT was conducted by ACZ under the supervision of SRK and was performed in accordance with the same standard methods as the earlier HCTs. The 2015 HCT materials derived from a metallurgical test tailings composite that combined two samples (BL-5-17 and BL-5-18) in equal fractions.

3.1.6 Mineralogy

The petrology and geochemistry of the various rock units in and near the PVM are described in U.S. Geological Survey Professional Paper 971 (Peterson, Gilbert, and Quick, 1951) and in various site characterization and consulting reports. Optical (polished thin section) petrography on ore and waste rock types, reflected light ore microscopy, X-ray diffraction of ore and mining wastes, and other analytical and mineralogy methods have been performed to assess the mineral types, percentages, and associations in the various ore and mine waste materials at PVM.

Mineralogical analyses consisting of petrography (optical microscopy), scanning electron microscopy, and powder x-ray diffraction were completed on waste rock samples by Petrographic Consultants International, Inc. (PCI, 2015). Their observations on the mineralogy and alteration of the dominant ore host and waste rock (quartz monzonite porphyry) in thin and polished section are



important in understanding potential mineralogy and chemical reactions of the tailings. Optical microscopy has been completed on the tailings samples by ALS Laboratory as part of the metallurgical testing program (Base Met, 2015). The petrology and geochemistry of the various rock units in and near the PVM were summarized in an SRK memorandum (SRK, 2016a).

The QMP phase of the Ruin Granite correlates closely in age and composition with the Precambrian Oracle Granite, which was the main host for ore at the San Manuel mine and tailings facilities at the San Manuel plant site at similar elevations, mining, processing, and tailings disposal methods, and climate to PVM. Extensive mineralogical, petrological, and geochemical investigations were documented in the Tailings Characterization Report (SRK, 2005) submitted to ADEQ for the APP application related to the closure of the San Manuel tailings facilities. Owing to the close similarity in ore host and tailings material, selected comments discussed below in Section 4.2.6 will incorporate observations and common conclusions at both PVM and San Manuel.

4 Geochemical Testing Results Results from three types or locations of samples are discussed in this section including the tailings from TSF3 and TSF4, and the metallurgical test tailings that represent future tailings to be deposited predominantly on TSF4 from approximately 2026 through the end of processing and tailings deposition in 2039.

4.1 Geochemical Test Results from TSF3 4.1.1 Paste pH Results from TSF3

The paste pH results on 34 samples from TSF3 are presented in Table 3. Twenty of the 34 samples were near neutral and had paste pH values that ranged from 6.2 to 8.24. Less than half of the paste pH values were acidic (14 of 34), ranging from 2.3 to 4.8.

Deeper samples [i.e. AH04-T3, TP3 (slimes), and TP3C (cyclone sands from the embankment) sample numbers] were near neutral or slightly alkaline. Surface samples (TE3 and SS04-T3 sample numbers) measured acidic pH values, ranging from 2.3 to 4.8 indicating oxidation has occurred in these samples. Some embankment materials are also acidic, which is consistent with the higher rate of oxidation in the coarser grained sand materials and less saturated conditions.

4.1.2 Acid-Base Accounting Results from TSF3

The results of the ABA analyses on 34 samples from TSF3 are presented in Table 1 and Figure 7. The analyses indicate that the tailings are either potentially acid generating or are in the uncertain range. Twenty-three of 34 TSF3 samples returned values of NNP between +1.1 and -17, placing them in the uncertain range. Eleven of the 34 samples returned values of NNP that were less than -20, which is in the acid-generating range. None of the samples returned values of NNP that were in the acid neutralizing range. The two Tailings Solid BL samples are included in Figure 7 for comparison with earlier TSF3 samples. Most of the Tailings Solid BL values are within the same min to max range of earlier samples.

The NPR ratios of the TSF3 samples varied between 0.01 and 1.10, which places the samples in the uncertain or acid-generating range. Thirty-one of 34 samples were between 0.01 and 1.0, placing them in the category that is more likely to generate acid. Three samples were between 1.0 and 1.25, placing them in the uncertain range. None of the samples had NPR >3, which is the range of low risk to generate acid.

Sulfur speciation in TSF3 (Table 1) varies between total sulfur percentages of 0.39% to 2.07%. Total sulfur percentage is the sum of pyritic sulfur, sulfate sulfur, and sulfur residue percentages. Pyritic sulfide ranges from 0.04% to 1.09% in the tailings slimes, with most samples having approximately 0.5% pyritic sulfur. Sulfate sulfur varies from 0.01% to 1.81%. Sulfur residue ranges between 0.01% and 0.65%.



4.1.3 Total Metals Results from TSF3

The results of the multi-element geochemistry analyses on TSF3 samples are presented in Table 4 and Figure 8. For reference purposes, the results for the samples are compared against Arizona NRSRLs, Arizona GPLs, and Global Abundance values for crustal rock and soil materials.

There were no exceedances of NRSRLs or GPLs. Water after contact with these tailings solids is not expected to exceed numeric groundwater quality standards (AWQS).

The results of the TSF3 samples indicate all four samples reported values of copper and six samples selenium that were elevated with respect to global abundances. Trace metals, such as copper and selenium, are commonly found in elevated concentrations in the immediate vicinity of porphyry copper ore deposits in comparison to the average Global Abundance concentrations. The two Tailings Solid BL samples are included in Figure 8 for comparison with earlier TSF3 samples. Some of the Tailings Solid BL values are outside the min to max range of earlier samples.

4.1.4 SPLP Results from TSF3

The results of the SPLP leachate analysis on the bulk composite sample of the TSF3 samples are presented in Table 5 and Figure 9. For reference purposes, the results were compared against ADEQ’s AWQS and EPA’s Maximum Contaminant Levels (MCLs) for National Primary Drinking Water (DW).

No samples of SPLP leachates from TSF3 exceeded the AWQS or EPA National Primary DW MCLs.

Analytical results on SPLP leachate samples from TSF3 indicate there were exceedances of the EPA National Secondary DW MCLs for aluminum (3 of 7 samples), copper (3 of 7 samples), iron (1 of 7 samples), manganese (5 of 7 samples), and pH (5 of 7 samples ranged from 2.8 to 6.2 SU. EPA Secondary DW MCL standards for pH range between 6.5 to 8.5 SU. Exceedances were in leachates derived from shallow surface samples, except the exceedance of manganese in auger hole AH 04-T3-15P at depths from 10-15 ft of 0.065 mg/L compared to the EPA Secondary DW MCL of 0.05 mg/L. Two of seven samples (depths of 10 to 20 ft) of the SPLP leachate were slightly alkaline with a paste pH of 7.7. The results indicate that water runoff after contact with these tailings (especially surface materials) have the potential to be acidic and exceed Secondary DW MCLs.

4.2 Geochemical Test Results on Samples from TSF4 4.2.1 Paste pH Results from TSF4

The paste pH results on 32 samples from TSF4 and two composite metallurgical test tailings are presented in Table 6. Paste pH values were near neutral and ranged from 6.9 to 8.2 on 24 of the 32 tailings samples. Seven of the 32 samples reported acidic values of 2.6 to 4.3; these samples were all shallow surface samples. The metallurgical test tailings had slightly alkaline paste pH values of 8.2 to 8.3.

Paste pH data are circum-neutral in TSF4 and are variable in embankment materials, ranging from neutral to 2.6. Water levels below the embankment at TSF4 are at least 150 feet below ground surface based on water level measurements in compliance monitoring wells outboard from the toe of the tailings embankment, suggesting a thick unsaturated zone is present in these materials, which is consistent with the higher rate of oxidation in the embankment zone.

4.2.2 ABA Results from TSF4

The results of the ABA analyses on the TSF4 tailings and the metallurgical test tailings are presented in Table 6. The analyses indicate that the tailings are either of the uncertain potential to generate acidic drainage or are confirmed to be potentially acid generating. The two Tailings Solid BL samples are included in Figure 7 for comparison with earlier TSF4 samples. Most of the Tailings Solid BL values are within the same min to max range of earlier samples.

Twenty of 32 samples from TSF4 returned values of NNP between 3 and -17.2, placing them in the uncertain range. Eleven of the 32 samples returned values of NNP that were less than -20, which is



in the acid-generating range. Metallurgical residue sample “Tailings Solid BL-5-17” reported an NNP of +1.06 t CaCO3/kt and sample “Tailings Solid BL-5-18” reported an NNP of -3.06 t CaCO3/kt, placing them in the uncertain range.

The NPR ratios of the TSF4 samples varied between 0.01 and 1.60, which places the samples in the uncertain or acid-generating range. Twenty-eight of 32 samples had an NPR between 0 and 1.0, placing them in the category that is more likely to generate acid. Five samples had NPR values between 1.0 and 1.6, placing them in the uncertain range. None of the samples had NPR >3, which is the range of low risk to generate acid. The metallurgical tailings samples reported NPR of 1.18, placing it in the uncertain range, and 0.78, indicating likely acid generation.

ABA analysis was compared with historical results taken from Cottonwood Tailings Impoundment and from TSFs No. 1, No. 2, No. 3, and No. 4 (Schafer, 1995; MWH, 2005). The comparison is presented in Figure 10. Values for the metallurgical residue samples for likely future tailings are within the range of historic results.

The NAG test results on the metallurgical test tailings in Table 6 indicate that Tailings Solid BL-5-17 has a net acid generating potential of 3 kilograms of sulfuric acid per tonne of rock (kg/t), and Tailings Solid (BL-5-18) has a net acid generating potential of 8 kg/t. NAG pH values of the samples are 4.3 for sample BL-5-17 and 4.4 for sample BL-5-18, indicating that the tailings will be potentially acid generating. The marginally acidic NAG pH and relatively low sulfuric acid production classify the tailings as having low capacity for acid generation (IWARK and EGi, 2002).

Sulfur speciation in TSF4 (Table 6) varies between sulfur total percentage of 0.21% to 2.27%. Pyritic sulfide ranges from 0.02% to 1.13%; pyrite is assumed to be the dominant residual sulfide mineral in the tailings after processing is completed to recover chalcopyrite and lesser copper sulfide minerals that are present in the deposit. Sulfate sulfur varies between <0.01% to 1.75%. Sulfur residue ranges between <0.01% and 0.53%.

4.2.3 Total Metals Results from TSF4

The results of the multi-element geochemistry analyses are presented in Table 7. For reference purposes, the results for the samples were compared against NRSRLs, Arizona GPLs, and Global Abundance values for crustal rock and soil materials.

There are no exceedances with respect to the NRSRLs or the GPLs. The results of the TSF4 samples indicate four of the six samples reported values of copper and selenium that were elevated with respect to Global abundance concentrations in all in surface samples. The results for the metallurgical test tailings also show selenium was elevated with respect to Global Abundance concentrations in both of the samples. Selenium was measured in the composite samples from metallurgical test tailings at a concentration of 2 mg/kg, which is greater than ten times the global abundance value of 0.12 ppm as indicated in Table 7. As mentioned previously, copper, selenium, and other associated trace metals are commonly found in elevated concentrations in ore deposits in comparison to the average Global Abundance concentrations.

Total metal analyses from the 2015 metallurgical residue samples were compared with historical results taken from Cottonwood Tailings Impoundment and from TSFs No. 1, No. 2, No. 3, and No. 4 (MWH, 2005). The comparison is presented in Figure 11. The metallurgical residue samples reported values that were generally at the upper end or above the range of historical results. Recent samples had higher concentration levels of aluminum, barium, and beryllium compared to historical values. The Tailings Solid (BL-5-18) sample had a higher concentration of silver compared to historical values.

Porphyry copper deposits have mineralization and secondary alteration halos that vary laterally and vertically with respect to the centroid of the ore-forming magmatic intrusion(s). Changes in metal concentrations relative to previous samples are expected because mining uncovers deeper portions of the deposit over time with variations in rock type, alteration and mineralization signatures, and the concentrations of individual constituents and the ratios of one constituent to another. Some of the difference in reported values for the metallurgical residue samples may be attributed to changes in method detection limits (MDLs), such as is apparent in antimony and thallium. The two Tailings Solid



BL samples are included in Figure 8 for comparison with earlier TSF4 samples. Most of the Tailings Solid BL values are within the same min to max range of earlier samples.

4.2.4 SPLP Leachate Results from TSF4

The results of the SPLP leachate analysis on TSF4 samples are presented in Table 8. For reference purposes, the results were compared against AWQSs and EPA MCLs for National Primary Drinking Water. One surface sample (SS04-T4-48) exceeded the AWQS or EPA primary DW MCLs for beryllium and cadmium.

Eight of 11 samples of the leachate are near neutral with pH between 6.9 and 7.8. Three of the 11 samples reported acidic paste pH values between 3.5 and 4.3, which are more acidic than the EPA National Secondary DW MCLs. Exceedances of EPA National Secondary DW MCLs occurred in five of 11 samples for aluminum, two samples for copper, and one sample of manganese. These exceedances were in the surface samples and in one auger hole for aluminum.

The results of these limited test results indicate that water after contact with TSF tailings may generate a near neutral to acidic water quality that exceeds selected numeric water quality standards.

4.2.5 MWMP Leachate Results from TSF4

The results of the MWMP leachate analysis on the bulk composite sample of the metallurgical samples are presented in Table 11. For reference purposes, the results were compared against AWQS, and EPA National Primary and Secondary DW MCLs.

With respect to AWQSs and EPA primary MCLs, all constituents meet numeric groundwater standards. The dominant constituents measured were bicarbonate, sulfate, calcium, potassium, sodium, and magnesium.

The MWMP leachate from the metallurgical test tailings is slightly alkaline with a pH of 8.3, but is within the range of EPA National Secondary DW MCLs.

Differences are apparent between the ABA data and the MWMP leachate data on the metallurgical tailings samples. The MWMP data indicate relatively benign drainage with neutral pH, while the ABA data indicate that the tailings have the potential to generate acid drainage. The reason for the difference is likely a function of the types and occurrences of minerals present in the rock, as detailed below:

• The rock leaches sulfate at a concentration of 40 mg/L, but no iron. This indicates that sulfate minerals such as gypsum or anhydrite may be producing a significant portion of the sulfate in the leachate rather than iron sulfates or iron sulfides.

• The tailings samples contain 0.19% and 0.45% sulfide, yet iron is below detection limits in the MWMP leachate. This reflects the inability of the short-term leach tests to oxidize sulfide minerals like pyrite and chalcopyrite.

• The neutral pH of the MWMP leachate indicates that availability of readily leachable acid neutralizing minerals, such as fracture filling carbonates, exceeds that of acid generating secondary sulfate minerals.

MWMP analyses of the metallurgical test tailings composite was compared with historical MWMP results taken from the Cottonwood Tailings Impoundment and TSFs No. 1, No. 2, No. 3, and No. 4 (MWH 2005). Measured values for the metallurgical testing composite (“Tailings Solids Combined”) were generally within the range of historical results (see Figure 12). Some constituents had differences in minimum values likely attributed to changes in the MDL. For reference, the historical SPLP analyses are also shown on Figure 12.



4.2.6 Mineralogy Results on TSF3 and TSF4

As mentioned previously, the main PVM ore host is QMP and refers to a porphyritic phase of the Ruin Granite of Precambrian age (1415 to 1485 million years ago (Ma) (Reynolds and others, 1986). Other ore types include diabase and aplite.

Ruin Granite at PVM is a massive intrusion of biotitic quartz monzonite, consisting of about 30% quartz, 20-25% orthoclase, 30% plagioclase, and variable smaller proportions of subhedral books of dark-brown biotite and oriented needles of rutile. Minor accessory minerals include sphene, apatite, and ilmenite or titanian magnetite, apatite, titanite, and zircon (rare). QMP contains low concentrations of acid-neutralizing minerals such as calcite, and 0.25-3% sulfides including pyrite is present (SRK, 2014). Note that the results of ABA testwork indicate the total sulfur species remaining in the metallurgical test tailings following ore processing is less than 1.81% in the TSF3 tailings samples and 1.02% in TSF4 samples.

From the petrographic work completed on the metallurgical test tailings (PCI, 2015), sulfide mineral grains were observed in two forms:

• Fully liberated grains, often very coarse especially in the rougher tailings (Figure 13); • Fine grains of chalcopyrite and pyrite encapsulated in silicate gangue (Figure 14).

Mineralogy and morphology is one of the key factors in terms of assessing sulfide oxidation and sample reactivity related to field weathering conditions. Coarse crystalline sulfide grains, although potentially exposed to oxygen and water, will have a high inherent chemical stability if encapsulated in non-reactive minerals such as quartz, so that oxygen reactions will be extremely slow, possibly over geological time (SRK, 2016b).

By contrast, the finer grained sulfides such as those found in slimes have more surface area and are more likely to be reactive if exposed to oxygen and water. The slimes typically occur in deeper, submerged, less oxygenated zones of the TSF and likely fully or partially encapsulated by non-reactive silicates. They are unlikely to react or less likely to react until the encapsulating silicate gangue is weathered or cracked, thus exposing the sulfide to weathering.

As a consequence, despite the ABA results and presence of sulfides, the tailings are predicted to have low reactivity and the release of any acid or metals would likely occur at low concentrations and over a long period of time. Thus although ABA analysis, completed on pulverized samples, indicates net potential for acid generation, the texture of the sulfides in the tailings would reduce this potential and consequently in the leach tests (completed on coarser or unprepared material) shows significant less reaction.

4.2.7 Humidity Cell Test Results on TSF4 Samples

A 26-week humidity cell test was completed by MWH on fresh tailings from TSF4 and CTI as an addendum to site characterization work completed in 2005. The common parameters, major cations/anions, metals, and metalloids analyzed during the testwork are listed in Table 12. The TSF4 HCT sample (AH04-T4-24P) was taken from 10 to 20 feet below the tailings surface and the CTI HCT sample (DH04-CT-03P) was taken from 30 to 35 feet below the CTI tailings surface. These materials were unoxidized tailings samples from the most recent and oldest tailings at site (MWH, 2006). The tailings samples were first tested for ABA characteristics.

Sample AH04-T4-24P from TSF4 returned the following results (Table 13 and Table 14):

• Acid Generating Potential = 33 tons/kiloton, • Acid Neutralizing Potential = 18 tons/kiloton, • Net Neutralizing Potential = -15 tons/kiloton (classifying an uncertain ARD potential), • Neutralizing Potential Ratio = 0.55 (classifying as potential ARD generator), • Total Sulfur = 1.05 percent, • Pyritic Sulfur = 0.88 percent (sufficient sulfide for ARD generation), and



• Paste pH = 7.5.

Weekly indicator parameter results for sample AH04-T4-24 are presented in Table 13, and additional parameter results from weeks 1, 10, 20, and 26 are presented in Table 14. The HCT test results are presented graphically in Figure 15 for pH, Figure 16 for specific conductivity, Figure 17 for sulfate, Figure 18 for TDS, Figure 19 for calcium, Figure 20 for cumulative sulfate, and Figure 21 for alkalinity.

The results of the two tailings material samples (TSF4 and CTI) indicate that throughout the 26-week cycle, the tailings leachate remained slightly alkaline and did not produce acid. The dominant cations observed were calcium and magnesium with sulfate as the dominant anion. Metals and metalloids were generally below detection (antimony, arsenic, cadmium, lead, selenium, and thallium) or not elevated in these samples suggesting they are not present in large quantity or in a soluble form. The dominant metals present above detection include copper, iron, manganese, and zinc reflecting the residual trace metals associated with the ore deposit.

The TSF4 sample had an average pH of approximately 8.5, which was higher than that of CTI, likely a result of a higher percentage of reactive carbonate and more recent age of the tailings material (MWH, 2006). Specific conductivity, sulfate, total dissolved solids (TDS) and calcium exhibited similar trends in both tailings facilities. The elevated concentrations of many of the indicator parameters in weeks 3 through 7 suggest accelerating sulfide oxidation, but the concentrations rapidly decreased between weeks 7 to 14, so the reaction was apparently not able to proceed at an accelerated rate (MWH, 2006).

Alkalinity release from the 2004 HCT on the TSF4 sample is consistent with the higher neutralizing potential of the TSF4 sample. A slight upward trend in alkalinity from TSF4 is noted in Figure 21. This is inversely related to the apparent increased rate of sulfide oxidation early in the test. These results indicate that in the laboratory, using the HCT test procedures, the older CTI sample is behaving as mostly inert material, while the TSF4 sample is only able to maintain a very low rate of sulfide oxidation (MWH, 2006).

Despite the ABA results and presence of sulfides in the TSF4 tailings, the HCT laboratory data supports the observation that ARD generation from fresh tailings is delayed, often by years, and the overall ARD reactivity is relatively low. Some potentially ARD-generating tailings on the surface of TSF4 had not turned acidic after approximately seven years of weathering (at that time). After cycle 1, the water quality of the leachate exhibits relatively low levels of metals and other analytes. The HCT data suggest that low reactivity and the release of any acid or metals would likely occur at low concentrations and over a long period of time. The texture of the sulfides and encapsulation by less reactive host minerals (quartz, potassium feldspar) may be an important contributing factor to reduce this ARD potential and mitigate the potential impacts to groundwater predicted by the results of short-duration static testwork.

4.2.8 Humidity Cell Test Results on Metallurgical Test Tailings

Results for the 2015-2016 testwork on metallurgical test tailings representing future tailings production) indicate the cell has exhibited relatively slow rates of solute release and circum-neutral pH throughout the duration of the 53-week test (SRK, 2016). Early time (weeks 0-1) pH values exceeded 8.0 but after week 25 stabilized to 6.6 - 6.9 (Figure 22). Acidity reported below detection level in all weeks reflecting the neutral pH. Sulfate concentration peaked at 35.1 mg/L in week 2 but decreased steadily until week 48 when it started increasing slightly to 5.7 mg/L at termination (Figure 23). Iron was only detected in three of the weekly leachate analyses, and no metal concentrations exceeded regulatory criteria in any analyses.

A closedown procedure was done on the HCTs as prescribed in Price (2009). The procedure includes analyses of both a final rinsate and the final sample residue. The final rinsate chemistry is shown in Table 15. The data indicate that secondary weathering products accumulated in the cells, as indicated by elevated concentrations compared to the week 53 leachate data. Elements accumulating in the cells as a result of this process include aluminum, barium, calcium, iron



potassium, magnesium, sodium, antimony, silicon, strontium, uranium, carbon (as both alkalinity and carbon), fluorine, nitrogen (as nitrate + nitrite), and sulfur.

The results of the ABA analysis on the final test solids indicate the tailings are in the uncertain acid-generating range (Table 16). The NNP was 0.25 and the NPR was 1.25. With the uncertain acid-generating NNP limits of -20 to +20 and the NPR limits of 1 to 3 the sample results are in the uncertain acid-generating range. The pyritic sulfur was 0.23%, the sulfur sulfate was 0.055% and the total sulfur was 0.28%. These results are consistent with the initial analysis of the sample at the start of the HCT.

4.3 Conclusions from Geochemical Test Results on Representative Future PVM Tailings

Samples of tailings derived from metallurgical testing have the potential to generate acidic drainage, based on ABA and NAG results (SRK, 2015b). The potential for acid generation is indicated by the NPR values of 1.18 and 0.78 and supported by element depletion rates in the humidity cell test. Paste pH values on the tailings samples are 8.2 and 8.3, indicating the absence of acidity in soluble secondary minerals.

Total element analysis indicates that aluminum, calcium, iron, magnesium potassium are the major elements present and reflect the composition of the rock-forming minerals. Pyrite and copper sulfide minerals were identified by site geologists in the drill core; the weight percentage of each mineral was noted on the drill logs for the overall sample interval. Carbonate minerals were not specifically identified and noted in the logs for these intervals but is present in small quantities in the ore materials in the rock matrix, along fractures, and as replacement minerals related to hydrothermal alteration. The laboratory results show elevated selenium concentrations with respect to Global Abundances. Selenium and other trace metals frequently occur associated with porphyry copper deposits in concentrations above average concentrations found in global continental crust.

The potential for mobility of trace metals from readily leachable minerals appears to be low based on the short-term MWMP leach tests on the metallurgical tailings and SPLP leach tests on the TSF3 and TSF4 samples. No constituents exceeded the reference AWQS or EPA national DW standards that are used to evaluate potential impacts to groundwater. Some samples returned values detected above the method detection limit (MDL), but below the practical quantitation limit. This suggests that the tailings would have low concentrations of readily leachable mineral phases with contained trace elements, but provides no indication of long-term acid drainage or metal leaching potential owing to sulfide oxidation.

The results of these analyses have been benchmarked against the previous results for samples taken directly from the various PVM tailings facilities and from the reclaim water. The geochemical test results for the metallurgical tailings are within the ranges documented in previous site testwork from 1995 through 2009 on actual tailings and for the water samples taken between 1993 and 2013. The composite metallurgical test tailings samples are deemed by SRK to be adequate to represent the future tailings materials.

The 2015 HCT data indicate the cell generated circum-neutral to alkaline pH throughout the duration of the test and relatively low element concentrations in cell leachate. Early alkaline pH values stabilized to 6.6 to 6.9 after week 25. Acidity reported below detection level in all weeks reflecting the near-neutral pH. Sulfate concentration peaked at 35.1 mg/L in week 2 but decreased steadily until week 48 when it started increasing again slightly to 5.7 mg/L at termination. Iron was only detected in four leachate analyses, and no metal concentrations have exceeded regulatory criteria in any of the analyses.

Despite the appearance of relatively benign leaching behavior, the relative depletion rates of NP (as carbon) versus AP (as sulfur) are evidence that development of acidic drainage is a possibility. If the cell was continued and current rates of depletion persist, it is predicted that carbon in the sample would be depleted in 4 years, whereas sulfur (as sulfate and sulfide) would be depleted in 19 years. Considering that carbon (as carbonate) is the primary source of acid neutralization in these materials, acidic conditions would be established once the carbon is depleted and would persist until the sulfur is depleted. However, the slow depletion rates of carbon and sulfur indicate that reactivity



is relatively low in the tailings and although development of acidic drainage is possible, the reality is that it will take many years to observe this. Figure 24 shows the relative depletion rates of carbon and sulfur.

However, examination of the morphology of the sulfide minerals indicates that they may have limited availability owing to factors such as encapsulation and coarse grain size, thus suggesting that the sulfides will not be sufficiently reactive to produce acidic drainage.

Based on the combined static, kinetic, leach, and mineralogical data for the TSF4 metallurgical test tailings, it is predicted that TSF4, as a whole, will not produce acidic drainage, although runoff from oxidized uncovered portions of surface embankment materials may generate acidic drainage and will require best management practices to contain and manage the runoff. If acidic drainage is produced from the TSF as a whole, it is expected to require a very long time period to develop (on the order of thousands of years or more), based on the sulfide deportment.

Future impacts to groundwater during operations are expected to be similar in magnitude to current impacts, which presently include elevated sulfate and TDS. Impacts to groundwater from TSF4 under the closure scenario, which will occur under a predicted seepage rate of only 22 gallons per minute (gpm), will be diluted at a factor of more than 70 to 1 by natural recharge, which is predicted to be sustained long term at a rate of 1635 gpm based on numerical flow groundwater modeling.

The reclamation approach as described in Section 8 for the future closed TSFs assumes a minimum of one foot cover of local borrow materials (dominantly acid-neutralizing Gila Conglomerate or similar inert material) to minimize direct contact of precipitation with tailings, minimize infiltration and seepage, and to re-establish local vegetation.

5 Water Quality Data on Tailings Waters and Supernatant (Reclaim Water) Water quality data are presented in Table 17 for various major and trace elements, total dissolved solids, pH for samples of blended reclaim water from both TSFs, tailings reclaim water from TSF4 and TSF3, and the supernatant water from the two metallurgical testing tailings that represent future tailings.

Similarly to actual tailings solid-liquid content, the two metallurgical testing residuals provided by BaseMet to ACZ consisted of approximately 50% liquid supernatant fraction. The two supernatants were combined and analyzed for a suite of total metals plus wet chemistry analytes. The supernatant fluid is slightly alkaline with a pH of 7.7 and has relatively low concentrations of total solutes. In order of concentration, the dominant constituents are sulfate, bicarbonate, total organic carbon, calcium, potassium, fluoride, and sodium (Table 17).

The only elevated constituents in the supernatant from the metallurgical testing is fluoride, which exceeds the reference AWQS for fluoride (11.1 mg/L in the sample versus the AWQS of 4 mg/L). This is attributed to dissolution of naturally occurring fluorine-bearing minerals such as fluorite. There are no fluorine-containing chemicals used in the milling, flotation, or concentration processes based on information provided by PVM.

The results of the 2015 supernatant sample were compared with six analyses of tailings reclaim water from TSF4 and TSF3 taken in 1999, 2013, and 2016 (Table 17). There is broad similarity in the results despite the fact that the analyses were completed by different laboratories, lack consistency in the constituents analyzed, and have different minimum detection limits (MDLs) for the constituents. The MDLs are generally lower in the 2015 and 2016 samples relative to the earlier reclaim water samples.

Fluoride is elevated above the AWQS (4 mg/L) and EPA Secondary Drinking Water MCL (2 mg/L) in the historical reclaim water samples from TSF4 (4.3 mg/L in 1999), TSF3 (6.55 mg/L in 2016), in the 2015 metallurgical test residue supernatant (11.1 mg/L), and in the 2016 reclaim water (6.3 mg/L). Elevated fluoride, however, is not detected in PVM’s spring monitoring points (0.29 to 4.01 mg/L) or in the compliance groundwater monitoring wells downgradient of TSF3 and TSF4 (<0.50 to 3.16 mg/L) (SRK, 2016b).



With respect to EPA Secondary Drinking Water MCLs, total iron (0.3 mg/L) was exceeded (1.4 mg/L) in TSF4 water in 1999 and in TSF3 reclaim water in 1994 (13.2 mg/L), but measured in significantly lower concentrations in 2016 (<0.060 mg/L in dissolved, 0.17 mg/L total iron) and were not present in the 2015 supernatant sample. Total dissolved solids (TDS) standards were also exceeded with respect to EPA Secondary MCLs (500 mg/L) in TSF4 (2900 mg/L) and water from TSF3 pond in 1994 (2500 mg/L). TDS was not analyzed in the 2015 supernatant sample (SRK, 2016b) but was reported at similar concentrations in the 2016 water quality sample (2590 mg/L).

6 BADCT Measures The original BADCT demonstration for the TSFs was documented by Hargis + Associates (1995a) in the 1995 site-wide APP application. Four elements were considered: depositional (operational) practices, design and construction; reuse of tailings water, and stormwater runon and runoff control (Hargis, 1995b). The following sections summarize the BADCT measures implemented in the construction, operation, and closure of TSF3 and TSF4.

6.1 Design and Construction

The TSF3 starter dam was originally constructed in 1973-1974 as a homogeneous embankment of compacted soil consisting of clayey sands and gravels on volcanic bedrock using an upstream construction method. A small starter dam was also constructed southeast of the main starter dam to prevent tailings from flowing into Gold Gulch. Drainage blankets were constructed below and through the starter dam in the eastern and western stream beds. The drainage blankets empty into toe drains and then to seepage collection facilities (Hargis, 1995b).

TSF4 starter dam was originally constructed by the upstream method in 1977. The design consisted of an excavated dacite rock-fill embankment with a low-permeability cap on the upstream face. A 30-foot-thick layer of drain material was placed between the rock fill and soil cover of Gila Conglomerate with a 10-foot-thick layer of river run gravel placed on the Gila Conglomerate to act as a toe drain. A secondary dam was constructed 1,500 feet upstream to store the cyclone underflow slimes during facility start-up. This dam was covered by tailings by 1983 (Hargis, 1995b). The current dam face (below elevation 3,790 feet) has been reclaimed with a minimum 2-foot-thick soil cover, which is subsequently protected with 6 to 13 inches of rock armor, depending upon slope angle and locations (ADEQ, 2015).

A stability analysis for both TSF3 and TSF4 was undertaken by AFW in 2015. The work included installation of new piezometers, additional geotechnical field and laboratory investigations, and static and dynamic (seismic) stability analyses. The stability analyses completed for this study, as well as the assessment of previous stability analyses performed by AFW and other consultants, indicate that TSF3 and TSF4 are stable in their current condition. The calculated FOS values exceed the minimum prescribed Arizona BADCT static and dynamic design criteria of 1.3 and 1.0, respectively (AFW, 2015).

6.2 Operational Practices

Tailings are deposited into TSF3 and TSF4 using cycloning and spigotting to separate the coarse portion of the tailings from the slimes. The coarse fraction is used for dam construction. The slimes were used as low permeability liner material to decrease infiltration and seepage of the decant ponds during construction. For TSF4, tailings slimes were initially used to line the bottom of the impoundment to create a low-permeability base (ADEQ, 2015). This practice would be used in the future if high-permeability substrate conditions are encountered.

Beach widths are optimized to enhance dam stability. Dam stability is monitored using piezometers. TSF3 and TSF4 facilities are operated and inspected quarterly by the Engineer of Record (AFW) according to the APP requirements for compliance monitoring and reporting to ADEQ.

Decant water is recycled to the mill process water system and seepage and stormwater runoff are directed to downstream intercept ponds and basins. The facility components are regularly inspected and periodically maintained to ensure proper operation.



6.2.1 TSF3

TSF3 is currently being used as a backup storage facility. The facility is used when the mill tailings flow rate is below the minimum flow rate required for gravity pipe flow to the TSF4 booster pump station or when the TSF4 tailings distribution system is being maintained. The facility received 714,822 tons of tailings in 2015. The TSF3 embankment crest elevation at the end of 2015 was 3,756 feet (AFW, 2016).

Three new groups of open standpipe piezometers equipped with vibrating wire piezometer tips were installed in 2015 at TSF3. The operation of TSF3 also transitioned to a combination of peripheral spigotting and the use of single point discharge stations at the northwest embankment abutment. This change has significantly improved the supernatant pool management. A new trailer-mounted centrifugal decant pump has also proven effective in maintaining a smaller sized supernatant pool. The planned combined TSF3 and TSF4 pump station was under construction at the time of the annual inspection in 2015. It is understood that this facility will be placed in service in mid-2016. The new pump station is expected to provide operational flexibility in the management of TSF3 (AFW, 2016).

6.2.2 TSF4

The primary storage facility for PVM is TSF4. The facility received 18,609,517 tons of tailings in 2015. The cyclone sand embankment crest of the facility was raised from about elevation 3,855 feet in January 2015 to 3,870 feet at the end of December 2015. Thirteen new open standpipe piezometers were constructed at TSF4 in 2015 and were equipped with vibrating wire piezometers automatically measured daily with data logger devices (AFW, 2016).

6.3 Reuse of Tailings Water

Decant pond size is minimized by constant reclaiming and recycling of decant water to the process water control system. In addition, contact stormwater and embankment toe seepage is also captured and returned to the process water system.

At TSF3, all stormwater runoff and seepage collected in the nearby East Catchment and East Catchment Caisson, Slack/Conklin Pond, West Catchment, No. 3 Seepage Caisson, and Canyon Dam Pond is returned to the mill process water system, except for overflow that is permitted through AZPDES Outfall 003. The facility is operated as a closed-circuit system that meets BADCT requirements.

At TSF4, stormwater and seepage is collected in Yasin Impoundment, Rosa’s Pond System, Road Pond and Charlie Pond and returned to the mill process water system.

6.4 Stormwater and Seepage Controls

TSF3 and TSF4 stormwater and seepage controls consist of a series of toe drains, pipelines, tanks, impoundments, caissons, and diversion ditches designed to capture and commingle seepage and contact stormwater for return to the mill process water system. Major components for each TSF are described in the following sections (ADEQ, 2015).

6.4.1 TSF3

The East Catchment and East Catchment Caisson are located on the east side of TSF3 and collect stormwater runoff and seepage from it. East Catchment was excavated into the natural soil and the bottom and embankments were constructed of imported compacted fill, with accumulated fine particulates providing a low-permeability bottom to the pond of 1 x 10-3 cm/sec or less. The Caisson is installed within the East Catchment. The storage capacity of the facility (5.52 acre feet) is sufficient to contain the 100-year, 24-hour storm event and normal operating discharges.

Slack/Conklin Pond is located downstream and due north of the center of TSF3 dam and is between East Catchment and Canyon Dam Pond. The pond was constructed by excavating down in native soil and the embankment shall be maintained as an engineered, permitted, jurisdictional dam fitted with a concrete spillway. Slack/Conklin Pond collects stormwater runoff and seepage from a small



drainage area below TSF3, overflow and seepage from West Catchment, pumped discharge from No. 3 Seepage Caisson, and is an alternate collection point for water pumped from Canyon Dam Pond. Commingled seepage and stormwater runoff discharge to Tank 16 on TSF3 decant pond, and overflow is captured by Canyon Dam Pond. Seepage from Slack/Conklin Pond is collected in No. 3 Seepage Caisson. This pond has a storage capacity of 51.10 acre-feet, sufficient to contain the 100-year, 24-hour storm event.

The No. 3 Seepage Caisson is located west of and downstream of Slack/Conklin Pond. This vertically emplaced pipe collects seepage from the French drain system located below Slack/Conklin Pond. The seepage is pumped back to Slack/Conklin Pond by a submersible, level-actuated pump, which has sufficient capacity to return all flow to Slack/Conklin Pond. The pipe has a storage capacity of approximately 2,000 gallons. Minor seepage that might bypass the caisson is captured by Canyon Dam Pond.

Canyon Dam Pond is located approximately 1,000 feet west of and downstream of Slack/Conklin Pond. This dam is constructed into native soil with an embankment constructed of imported compacted fill. The bottom of the facility was also constructed from compacted fill and is lined with accumulated sediment. The dam is equipped with a concrete spillway that acts as an AZPDES outfall. The pond behind the dam collects stormwater runoff and seepage for the drainage area located west of the TSF3 and below Slack/Conklin Pond. A diversion ditch is located upstream and to the southwest of Canyon Dam to divert undisturbed stormwater runoff. This pond has an 8.56 acre-feet storage capacity, sufficient to contain the100-year, 24-hour storm event. Commingled stormwater runoff and seepage discharges are pumped to Slack/Conklin Pond or Tank 16; and overflow shall be directed to AZPDES Outfall 003.

West Catchment is located downstream of the westernmost portion of the No. 3 Tailings Impoundment dam. This retention pond captures stormwater runoff from the TSF3 dam face and from the header road located at the top of the dam. West Catchment was excavated into the natural soil and the embankment was constructed of imported compacted fill. The bottom of the facility is formed from compacted fill and accumulated fine sediment with an estimated low permeability of 1 x 10-3 cm/sec. A barge pump is used to pump discharge to Slack/Conklin Pond or Tank 16. The basin has a storage capacity of 7.90 acre-feet, augmented by gravity overflow to Slack/Conklin Pond, which can contain the 100-year, 24-hour storm event.

6.4.2 TSF4

At TSF4, stormwater and seepage is collected in Yasin Impoundment, Rosa’s Pond System, Road Pond, and Charlie Pond, which have been upgraded to increase capture of seepage from the dam. Non-contact stormwater is diverted around the embankment on the north side, through a sedimentation area for eventual discharge to Pinto Creek. Yasin Impoundment is located on TSF4 to collect embankment face stormwater commingled with TSF4 pumping station spillage. Charlie and Road ponds and the Rosa’s Pond System are all part of BADCT for TSF4 and collect and divert contact stormwater from the face of the tailings to downstream structures.

Rosa’s Pond System is located at the downstream toe of TSF4 dam near the center of the dam. The system consists of one evaporation pond excavated into the native ground, the bottom of which is highly impermeable. The estimated permeability of the pond base is 1 x 10-3 cm/sec or less. Rosa’s Pond System collects seepage and stormwater runoff from the face of TSF4 dam and the area below Yasin Impoundment. Rosa’s Pond System is designed and maintained as a containment and evaporation area and is not equipped with a pumping system. The capacity of 2.85 acre-feet is sufficient to contain the 100-year, 24-hour storm event.

7 Surface Preparation Measures for TSF4 Expansion Surface preparation involves stripping of existing vegetation, debris, and other deleterious materials. Stripped material consisting of vegetation and organic materials should be disposed outside the tailings dam impoundment area in fill sections not exceeding 5 feet in height. Select tailings basin areas with highly permeable substrata will be lined with a low permeable slimes layer to minimize infiltration and seepage.



8 Reclamation of TSF3 and TSF4 TSF draindown will take approximately 10 years after closure before reclamation can commence. During this time period, dust control measures will be implemented and may consist of temporary water sprays, dust covers, or application of other commercial dust control additives to the top of the tailings. Following draindown, re-contouring of the TSFs will be performed by bulldozers, which will be used to lessen the slopes by pushing up-slope material down the slope or pulling down-slope material up the slope to create a shallower slope angle. The tops of the TSFs will be re-contoured to promote drainage and prevent water from ponding. Bulldozer operations may be augmented by a grader or scraper, as appropriate. The reduction of selected side slopes for closure can begin as soon as the area becomes inactive.

A cover will be utilized to reduce erosion, re-establish site vegetation, and reduce or eliminate infiltration of storm water through the cover to the TSF surface, thus minimizing the potential impact to groundwater. The TSF cover will consist of non-acid generating soil, typically Gila Conglomerate and/or Whitetail Conglomerate but also other materials as available and appropriate, excavated from a borrow area, hauled, and placed at a minimum depth of a 1 foot. Addition of amendments such as organics, straw/mulch, and/or fertilizers, will be evaluated. Conventional fertilizer trucks may be used to spread the required organics, and/or granular fertilizer. A heavy-duty disc or chisel plow will likely be utilized to work any required amendments into the growth media by discing or chiseling on the contour.

Growth media not requiring amendment will be ripped or scarified prior to seeding. Seed will be either broadcast simultaneously with the fertilizer or drilled with farm equipment. On some steeper slopes, it may be necessary to use a hydroseeder/hydromulcher to apply the required amendments and seed. GeoSystems Analysis, Inc. (GSA, 2015) recently evaluated the historic PVM seed mix. GSA recommended removal of three species from the seed mix; addition of one species, and modification of the application rates for three species based on consideration of local climate and seed availability. The seed mix will be re-evaluated for actual seed availability and revised, if needed, prior to beginning seeding activities

Surface drainage control associated with the reclaimed TSFs will be provided after closure of the facility. The existing TSF catchments and ditches will include diversion of runon stormwater. Ponds and ditches no longer necessary will be closed by cutting and filling to promote drainage through these areas. These catchments and ditches will then be closed by pushing in berms, and cutting and filling to promote drainage and precipitation run-off.

8.1 TSF3

During the remaining mine life, TSF3 is planned to rise to a maximum crest elevation of 3,860 ft amsl. Closure of TSF3 will take place at the end of the project life after tailings consolidation has occurred (approximately 10 years after last use). The TSF3 downstream embankment face will be regraded to a 3H:1V interbench slope with an interbench drainage channel and covered with 2 feet of soil cover material followed by 6 inches of rock armor fill on the outslopes (AFW, 2016). The TSF3 top surface will be graded at a minimum 0.5% slope and covered with a minimum of one foot of cover material, which will be revegetated. Soil cover material will consist of Gila Conglomerate or similar inert material acquired from nearby borrow source area. Side slopes will be regraded to 3.0H:1V and covered by 2 feet of soil cover material followed by 6 inches of rock armor fill.

The TSF3 top bench stormwater diversion channel will connect to a drop channel on the northeast side of the TSF3 embankment to discharge stormwater to a northern perimeter stormwater run-on interceptor channel and existing ponds. This water will be discharged to a natural drainage when reclamation has been completed. Another top surface stormwater channel will constructed to eventually discharge to the natural drainage via a spillway on the western side of the impoundment following full reclamation.

Seepage from the embankment underdrains will be captured by the existing system located at the No. 3 Seepage Caisson, West Catchment, East Catchment, and East Catchment Caisson, where



fluids will be collected and a pump will be housed to convey those fluids to their ultimate location for the post-closure period (AFW, 2015).

8.2 TSF4

TSF4 is a planned to expand to a maximum crest elevation of 4,250 feet amsl. Closure of TSF4 will take place approximately 10 years into the post-closure period to allow for tailings consolidation. The TSF4 downstream embankment face will be regraded to a 3H:1V interbench slope with an interbench drainage channel and covered with 2 feet of cover material followed by 6 inches of rock armor fill on the outslopes. Two 20-ft-high divider berms are to be constructed to create a terraced tailings impoundment surface. Three cells will be formed, with the south cell (Cell C) being the highest and the north cell (Cell A) being the lowest (AFW, 2016). The TSF4 top surface of each cell will be graded at a 0.5% slope or steeper and covered with a minimum of one foot of soil cover material (Gila Conglomerate or other similar inert material) obtained from nearby borrow areas. The soil cover will then be revegetated.

The closure drainage design for TSF4 will consist of a conveyance channel running through all three cells that will collect flows and direct flows to a spillway located on west embankment face of the TSF4 facility and eventually to the natural drainages when TSF4 is fully reclaimed. Seepage will be captured in one or more impoundments throughout the post-closure period (AFW, 2015).

9 Post-Closure Facility Inspections, Maintenance, and Water Monitoring It is expected that post-closure maintenance and monitoring of site facilities, including some elements of closed facilities will be required for 30 years following final closure. Post-closure maintenance includes maintaining:

• access roads, • drainage facilities to ensure ditches, culverts, and ponds remain free of debris, • reclaimed areas impacted by erosion, • security measures throughout the mine site, and • monitoring locations (surface and groundwater monitoring locations) and support facilities.

TSF3 and TSF4 will be inspected periodically to monitor erosion and vegetation. In addition, the re-established drainages will be inspected periodically and after major rainfall events to make sure the retained stormwater diversions and riprap spillways are working properly. Seepage handling facilities will be subject to routine on-going maintenance. Areas that have been revegetated will be inspected periodically to monitor vegetation coverage and erosion control effectiveness. Areas not responding to revegetation efforts or areas that experience erosion will be repaired and reseeded.

Post-closure monitoring of groundwater monitoring wells and surface water discharge points will be in accordance with PVM’s existing permits as amended. Routine monitoring of groundwater Points of Compliance wells (POCs) will be conducted for a period of 30 years following the closure in accordance with PVM’s APP. Groundwater monitoring is currently performed on a quarterly or a biennial basis depending on the parameter being analyzed. It is anticipated that groundwater monitoring frequency will be decreased during the post-closure period following the completion of a minimum period of routine monitoring.

PVM’s Arizona Pollutant Discharge Elimination System (AZPDES) Permit No. AZ0020401 requires monitoring of a perennial discharge at Outfall 005. Other outfalls which are for point source discharges exceeding the 10-year, 24-hour storm event may remain in place and require periodic monitoring. For these outfalls water quality monitoring and reporting is required for several parameters including metals, flow, total suspended solids, pH, and hardness (CaCO3). This permit also requires ambient seep identification and monitoring for various parameters. Finally, the AZPDES permit includes a Best Management Practices Plan that requires monitoring of available surge capacity in all process and stormwater impoundments and routine inspection/maintenance procedures for ponds, berms, ditches, dikes, dams, containment structures, pipelines, and pump



stations. Solids must be removed when the impoundment storage capacity is less than 80% of the design volume.

In addition, PVM will retain coverage under the Arizona General Permit for Stormwater Discharges Associated with Industrial Activity-Mineral Industry (known currently as the AZMSGP-2010) for a number of years during the closure and post-closure period. This permit covers stormwater discharges at mining-related support functions, such as vehicular use of public and private roads to access active areas of the mine, disturbed areas such as borrow areas, construction areas, and laydown yards, well and pipeline/pump maintenance, containment/pump back systems maintenance and other functions. This permit also requires periodic inspection and maintenance of structural stormwater controls and monitoring of discharges from several discharge points throughout the property for various metals and other parameters. Once major facilities have been reclaimed satisfactorily and released from applicable reclamation bonds, PVM will terminate coverage under the AZMSGP.



10 References Arizona Department of Environmental Quality (ADEQ), 1996, Screening method to determine soil

concentrations protective of groundwater quality: published testwork guidance.

_____, 2004a, Arizona mining guidance manual – BADCT: ADEQ Publication # TB 04-01, 182 p, 6 appendices, accessed May 18, 2012, http://www.azdeq.gov/environ/water/wastewater/download/badctmanual.pdf

_____, 2004b, Appendix B – Solution, ore, and waste characterization in Arizona Mining Guidance Manual – BADCT: ADEQ Publication # TB 04-01, 20 p.

_____, 2015, Aquifer Protection Permit P-100329, Pinto Valley Mine: environmental permit issued to Pinto Valley Mining Corp., October 21, 2015, 78 p.

AJAX, 2014, Pinto Valley Phase 3 Metallurgical sample collection memorandum: unpublished memorandum prepared for P into Valley Mining Corp. by G. Lenzi, October 28, 2014, 3 p.

Amec Foster Wheeler (AFW), 2015, Static and dynamic analysis and piezometer replacement program, Tailings Storage Facilities No. 3 & No. 4, Phase 2 Extension, Pinto Valley Mine, Gila County, Arizona: unpublished report prepared for Capstone Mining Corp., August 3, 2015, 66 p., 8 appendices.

_____, 2016, Tailings impoundments 2015 monitoring program, Pinto Valley Mine, near Miami, Arizona: unpublished report prepared for Pinto Valley Mining Corp. and submitted by PVMC to ADEQ, March 3, 2016, 18 p., 2 appendices.

ASTM, 1998, Standard test method for shake extraction of mining waste by the synthetic precipitation leaching procedure, Designation D6234-98 (reapproved 2007): ASTM, West Conshohocken, Penn., 7 pp.

_____, 2007, Standard test method for laboratory weathering of solid material using a humidity cell: American Society for Testing and Materials (ASTM), West Conshohocken, Pennsylvania, USA, ASTM method D5744-07, 19 pp.

_____, 2012, Standard test method for column percolation extraction of mine rock by the Meteoric Water Mobility Procedure, Designation E2242-12: ASTM, West Conshohocken, Penn., 8 pp.

Base Metallurgical Laboratories (Base Met), 2015, PV3 metallurgical testing of future ores from Pinto Valley: report BL0005 prepared for Capstone Mining Corp., January 20, 2015,141 p.

GeoSystems Analysis, Inc. (GSA), 2015, Pinto Valley seed mix review: unpublished technical memorandum prepared for SRK Consulting, Inc., April 28, 2015, 6 p.

Hargis + Associates, 1995a, Preliminary hydrogeologic report, Magma Copper Company, Pinto Valley Mining Division, Miami, Arizona: unpublished report for Magma Copper Company, Pinto Valley Mining Division, 196 p.

_____, 1995b, Preliminary Best Available Demonstrated Control Technology Assessment, Magma Copper Company, Pinto Valley Mining Division, Miami, Arizona: unpublished report prepared for Magma Copper Company, January 13, 1995, 6 volumes, 10 appendices.

Ian Wark Research Institute (IWARK) and Environmental Geochemistry International (EGi), 2002, ARD test handbook – AMIRA P387A Project, Prediction and Kinetic Control of Acid Mine Drainage: AMIRA International, Melbourne, Australia.



Lawrence, R.W., Poling, G.W., and Marchant, P.B., 1989, Investigation of prediction techniques for acid mine drainage, Coastech Research Inc., MEND Project 1.16.1a, CANMET Scientific

MWH, 2005, Site investigation results – Final draft: unpublished report prepared for BHP Copper Inc., April 2005, 61 p. plus tables, figures, and appendices.

_____, 2006, Pinto Valley humidity cell testing results: unpublished technical memorandum prepared for BHP Copper Inc., February 20, 2006, 18 p.

Peterson, N.P., Gilbert, C.M., and Quick, G.L., 1951, Geology and ore deposits of the Castle Dome area, Gila County, Arizona: U.S. Geological Survey Bulletin 971, plus plates.

Petrographic Consultants International, Inc. (PCI), 2015, Petrography of samples from a copper porphyry deposit: unpublished report for SRK Consulting (U.S.), Inc., on Pinto Valley Mine samples, March 28, 2015, 21 p.

Price, W.A., 2009, Prediction manual for drainage chemistry from sulphidic geologic materials, Mine Environment Neutral Drainage (MEND) Report 1.20.1, CANMET – Mining and Mineral Sciences Laboratories, Smithers, British Columbia, V0J 2N0, 579 p.

Reimann, C., and Caritat, P.d, 1998, Chemical elements in the environment, factsheets for the geochemist and environmental scientist, Springer-Verlag, Berlin, 398 pp.

Reynolds, S.J., Florence, F.P., Welty, J.W., Roddy, M.S., Currier, D.A., Anderson, A.V., and Keith, S.B., 1986, Compilation of radiometric age determinations in Arizona: Arizona Bureau of Geology and Mineral Technology (Arizona Geological Survey), Bulletin 197, 258 p.

Schafer & Associates, Inc. (S&A), 1995, Geochemical evaluation Magma Copper Company Pinto Valley Mine: unpublished report prepared Magma Copper Company Pinto Valley Mining Division, February 21, 1995, 200 p.

Sobek, A.A., Schuller W.A., Freeman, J.R., and Smith, R.M., 1978, Field and laboratory methods applicable to overburden and mine soils: Cincinnati, Ohio, U.S. Environmental Protection Agency (EPA), Industrial Environmental Research Laboratory, Office of Research and Development, Report EPA-600/2-78-054, March 1978, 203 [216] pp.

SRK Consulting, 2005, BHP San Manuel Plant Site - Tailings characterization report: unpublished report for BHP Copper Inc., submitted to ADEQ August 1, 2005, 364 p., plus 12 appendices.

_____, 2014, Pinto Valley geology summary for BADCT: unpublished report from D. Russin for Pinto Valley Mining Corp., May 9, 2014, 3 p.

_____, 2016a, Petrology and geochemistry of formations in and near the Pinto Valley Mine: unpublished memorandum from Jan Rasmussen to David Bird, SRK, February 9, 2016, 13 p.

_____, 2016b, Static and kinetic geochemical test results – Pinto Valley PV3 phase tailings composite sample: unpublished memorandum from David Bird to Capstone Mining Corp., March 31, 2016, 30 p.

U.S. Environmental Protection Agency (EPA), 1994, SW-846 Test Method 1312: Synthetic Precipitation Leaching Procedure, in SW-846, Test Methods for Evaluating Solid Waste, Physical / Chemical Methods. Available at: https://www.epa.gov/hw-sw846/sw-846-test-method-1312-synthetic-precipitation-leaching-procedure.



Tables



Table 1 Sample intervals selected for metallurgical and geochemical testing: Eastern Pushback, Northern Pushback, and Aplite Composite

Drill Hole ID Geochemical Sample ID From (ft) To

(ft) Weight (pound

s) Drill Hole

Location Areas

DDH-12-62

Composite Tailings Solid Sample (BL-5-

17)

310 320 27

Eastern Pushback

Low-Level Length

DDH-12-176 1210 1220 21 DDH-12-175 1330 1340 29 DDH-12-91 580 590 26 DDH-12-161 630 640 22

Mid-Level Length

DDH-12-156 510 520 22 DDH-12-3 950 960 21 DDH-12-156 610 620 25 DDH-11-33 Not included in

metallurgical sampling composite

420 430 27 Upper-Level

Length DDH-11-33 390 400 29 DDH-12-156 240 250 26 DDH-12-154 80 90 25 DDH-12-90

Composite Tailings Solid Sample (BL-5-

18)

640 650 27

Northern Pushback

Low-Level Length

DDH-12-55 410 420 24 DDH-12-8 500 510 19 DDH-11-20 440 450 24 DDH-12-79 50 60 14

Mid-Level Length

DDH-11-14 1280 1290 20 DDH-11-15 820 830 12 DDH-12-177 1150 1160 23 DDH-11-15 860 870 21 DDH-13-195 Not included in

metallurgical sampling composite

579 584 11

Aplite Composite DDH-13-194 381.5 394 29 DDH-13-194 465 479 31 DDH-13-194 576.5 583 16

Notes: TAILINGS SOLID (BL-5-17) sample is a 50-50 blend of Eastern Pushback Low and Mid-Level cores TAILINGS SOLID (BL-5-18) sample is a 50-50 blend of Northern Pushback Low and Mid-Level cores Supernatant combined liquid fractions of BL-5-17 and BL-5-18 Tailings Solid Combined is a 50-50 blend of BL-5-17 and BL-5-18 Source: AJAX, 2014



Table 2 Composite sample descriptions

Area Lithology Alteration Mineralization North Pushback, Mid Levels

Ruin Granite with small proportions of Aplite

Mostly Phyllic, with approximately 12-15% sericite and clay replacing feldspars. Minor potassic, with biotite replacing mafic minerals.

Chalcopyrite-dominated with lesser amounts of pyrite and traces of molybdenite. Some samples show evidence of weak supergene enrichment, with traces of covellite, bornite, and chalcocite. Approximately:

0.5-0.6% Chalcopyrite 0.1% Pyrite 0.01 Molybdenite

North Pushback, Low Levels

Ruin Granite with lesser Granodiorite

Weak Potassic, with quartz veins common and magnetite partially replacing igneous biotite. Phyllic alteration overprints Potassic, with approximately 17% sericite replacing feldspars and biotite.

Chalcopyrite-dominated with lesser amounts of pyrite and traces of molybdenite. Some samples show evidence of weak supergene enrichment, with traces of covellite, bornite, and chalcocite. Approximately:

0.4% Chalcopyrite 0.2% Pyrite 0.01% Molybdenite

East Pushback, Low and Mid Levels

Ruin Granite with small proportions of Aplite

Potassic, with approximately 3% biotite replacing mafic minerals and abundant quartz veins. Some samples overprinted by Phyllic, with approximately 15% sericite replacing feldspars and biotite. Calcite is common (0.3%)

Chalcopyrite-dominated with lesser pyrite and molybdenite

Approximately: 0.3% Chalcopyrite 0.1% Pyrite

0.01% Molybdenite

• Source: Compiled by SRK from PVMC drillhole database and drill logs



Table 3 ABA analytical results from TSF3

Parameter TD308-1 TD308-2 TD308-3 TP3-1 TP3-2 TP3-3 TP3-4 TP3-5 TP3-6 TP3C-1 TP3C-2 TP3C-3 TP3C-4 TP3C-5 TP3C-6 TE3-1 TE3-2 TE3-3 Acid Generation Potential (t CaCO3/Kt) 17.5 15.3125 19.0625 19.1 14.1 20.9 10.9 10 36.9 17.5 18.1 11.6 27.2 15 18.4 1.3 2.5 2.2

Acid Neutralization Potential (t CaCO3/Kt) 8 2 7 16 8 13 12 7 34 6 10 9 10 7 11 1 1 B 1 B

Paste pH 7.7 6.2 7.8 8.24 7.98 8.11 8.03 7.87 8.2 7.78 7.83 7.59 7.56 7.45 7.18 3.21 2.89 2.3 Sulfur Residue (%) 0.15 0 0.11 0.04 0.05 0.05 0.05 0.04 0.09 0.06 0.06 0.08 0.15 0.03 0.08 0.01 B 0.03 0.06 Sulfur Pyritic Sulfide (%) 0.56 0.49 0.61 0.57 0.4 0.62 0.3 0.28 1.09 0.5 0.52 0.3 0.72 0.45 0.51 0.03 0.05 0.01 Sulfur Sulfate (%) 0.06 0.17 0.08 0.01 0.16 0.09 0.12 0.15 0.01 B 0.15 0.09 0.09 0.04 0.06 0.01 B 0.46 0.37 0.42 Sulfur Total (%) 0.77 0.66 0.8 0.62 0.61 0.76 0.47 0.47 1.18 0.71 0.67 0.46 0.91 0.54 0.59 0.49 0.45 0.49 NNP = ANP - AGP -9.5 -13.3125 -12.0625 -3.1 -6.1 -7.9 1.1 -3 -2.9 -11.5 -8.1 -2.6 -17.2 -8 -7.4 -0.3 -1.5 -1.2 NPR = ANP / AGP 0.46 0.13 0.37 0.84 0.57 0.62 1.10 0.70 0.92 0.34 0.55 0.78 0.37 0.47 0.60 0.77 0.40 0.45 AGP (% Sulfur Pyritic * 31.25) 17.50 15.31 19.06 17.81 12.50 19.38 9.38 8.75 34.06 15.63 16.25 9.38 22.50 14.06 15.94 0.94 1.56 0.31

Initial Assessment (NNP >= 20) No No No No No No No No No No No No No No No No No No

Step 1 (NPR >= 3) No No No No No No No No No No No No No No No No No No Step 2 (NPR - using Sulfur Pyritic > 3:1) No No No No No No No No No No No No No No No No No No

Source WMC 2008

WMC 2008

WMC 2008

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc. MWH MWH

Parameter SS04-T3-42 GEOCHEM

(0-12)

SS04-T3-43 GEOCHEM

(0-12)

SS04-T3-44 GEOCHEM

(0-2)

SS04-T3-45 GEOCHEM

(0-12)

SS04-T3-46 GEOCHEM

(0-12)

SS04-T3-33 GEOCHEM

(0-12)

SS04-T3-41 GEOCHEM

(0-12 in)

SS04-T3-34 GEOCHEM

(0-5 in)

SS04-T3-35 GEOCHEM

(0-4 in)

SS04-T3-36 GEOCHEM

(0-12 in)

SS04-T3-37 GEOCHEM

(0-3 in) Acid Generation Potential (t CaCO3/Kt) 12 43 21 65 38 24 13 75 50 43 56

Acid Neutralization Potential (t CaCO3/Kt) 15 7 20 <1 15 <1 6 <1 <1 <1 1 B

Paste pH 6.2 4.4 6.9 2.4 6.8 3.4 3.9 3.1 3.3 3.6 4.8 Sulfur Residue (%) 0.27 0.65 0.22 0.58 0.49 0.1 0.12 0.31 0.14 0.23 0.47 Sulfur Pyritic Sulfide (%) 0.07 B 0.65 0.43 0.18 0.66 0.05 B 0.04 B 0.28 0.33 0.06 B 0.42 Sulfur Sulfate (%) 0.05 B 0.09 B 0.03 B 1.31 0.05 B 0.61 0.27 1.81 1.12 1.07 0.89 Sulfur Total (%) 0.39 1.39 0.68 2.07 1.2 0.76 0.43 2.4 1.59 1.36 1.78 NNP = ANP - AGP 3 -36 -1 -64.5 -23 -23.5 -7 -74.5 -49.5 -42.5 -55 NPR = ANP / AGP 1.25 0.16 0.95 0.01 0.39 0.02 0.46 0.01 0.01 0.01 0.02 AGP (% Sulfur Pyritic * 31.25) 2.19 20.31 13.44 5.63 20.63 1.56 1.25 8.75 10.31 1.88 13.13

Initial Assessment (NNP >= 20) No No No No No No No No No No No

Step 1 (NPR >= 3) No No No No No No No No No No No Step 2 (NPR - using Sulfur Pyritic > 3:1) No No No No No No No No No No No

Source MWH MWH MWH MWH MWH MWH MWH MWH MWH MWH MWH

SRK Consulting Pinto Valley TSF3 & TSF4 Characterization


Table 3 ABA analytical results from TSF3

Parameter SS04-T3-38 GEOCHEM

(0-12 in)

SS04-T3-39 GEOCHEM

(0-12 in)

SS04-T3-40 GEOCHEM

(0-10 in) AH04-T3-15P

(10-15 ft) AH04-T3-17P

(10-20 ft)

Acid Generation Potential (t CaCO3/Kt) 22 30 29 27 13

Acid Neutralization Potential (t CaCO3/Kt) <1 <1 <1 16 13

Paste pH 2.8 3 3.4 7.7 7.7 Sulfur Residue (%) 0.09 B 0.12 0.16 0.12 0.07 B Sulfur Pyritic Sulfide (%) 0.06 B 0.08 B 0.08 B 0.74 0.25 Sulfur Sulfate (%) 0.55 0.76 0.69 <0.01 0.1 Sulfur Total (%) 0.7 0.96 0.93 0.85 0.42 NNP = ANP - AGP -21.5 -29.5 -28.5 -11 0 NPR = ANP / AGP 0.02 0.02 0.02 0.59 1.00 AGP (% Sulfur Pyritic * 31.25) 1.88 2.50 2.50 23.13 7.81 Initial Assessment (NNP >= 20) No No No No No

Step 1 (NPR >= 3) No No No No No Step 2 (NPR - using Sulfur Pyritic > 3:1) No No No No No

Source MWH MWH MWH MWH MWH Notes: Schafer & Assoc. = Geochemical Evaluation of the Magma Copper Company Pinto Valley Mine (1995) SWS = SWS 2008-2009 = WMC, 2008 MWH = BHP Copper Inc. Pinto Valley Mine Site Characterization Report (2005a) B = Analyte concentration detected at a value between MDL and PQL. The associated value is an estimated quantity. Initial Assessment: Yes = NNP >=20 potentially acid neutralizing, No = NNP<20 uncertain or potentially acid generating Step 1: Yes = NPR >=3 potentially acid neutralizing, No = NPR <3 uncertain or potentially acid generating Step 2: Yes = NPR - using Sulfur Pyritic >=3 potentially acid neutralizing, No = NPR - using Sulfur Pyritic <3 uncertain or potentially acid generating



Table 4 Total metals analytical results from TSF3

Parameter (mg/Kg)

Non-residential

SRL GPL Global

Abundance TD308-1 SS04-T3-36 GEOCHEM (0-12 in.)

SS04-T3-37 GEOCHEM

(0-3 in.)

SS04-T3-38 GEOCHEM (0-12 in.)



Aluminum 920000 - 82300 0.3 3630 3700 4130 3100 3340 Antimony 410 35 0.2 0.4 <0.1 <0.1 0.1 B 0.1 B 0.2 B Arsenic 10 290 1.7 0.6 1.3 0.5 B 0.8 B 0.6 B 0.7 B Barium 170000 12000 425 36 52.6 73.1 38 128 124 Beryllium 1900 23 2.4 - 0.4 B 0.6 B 0.3 B 0.5 B 0.4 B Cadmium 510 29 0.1 0.2 <0.5 0.6 B 0.6 B 0.6 B 0.6 B Cesium - - - - 5 B 5 B 6 3 B 7 Copper 41000 - 60 315 767 999 257 1110 1050 Iron - - 56300 1.24 11600 10800 14700 7310 13200 Lead 800 290 14 8.4 3.69 3.64 6.4 6.45 8.57 Manganese 32000 - 950 191 57.5 128 57.8 174 111 Mercury 310 12 0.0625 <0.01 <0.04 H <0.04 H <0.05 H <0.04 H <0.04 H Selenium 5100 290 0.12 2.1 1.5 B 1.5 B 2 B 1.4 B 2.1 B Silver 5100 - 0.075 0.2 <0.5 <1 <1 <0.5 <1 Thallium 67 12 0.52 0.012 0.09 B 0.08 B 0.11 0.08 B 0.08 B Zinc 310000 - 70 51 35 47 44 95 38 Source SWS MWH MWH MWH MWH MWH Notes: Source: MWH, 2005a GPL = Groundwater Protection Levels, ADEQ, 1999 < values are based on MDLs B = Analyte concentration detected at a value between MDL and PQL. The associated value is an estimated quantity. H = Analysis exceeded method hold time. pH is a field test with an immediate hold time. Numbers in red indicate that concentration exceeds ADEQ Non-residential Soil Remediation Levels Numbers italicized indicate that concentration exceeds ADEQ Groundwater Protection Levels Numbers bold and underlined indicate that concentration is elevated above the global abundance by a factor of 10 or more SWS = SWS 2008-2009 MWH = BHP Copper Inc. Pinto Valley Mine Site Characterization Report (2005)



Table 5 SPLP leachate analytical results from TSF3

Parameter (mg/L unless noted)

AWQS / EPA Nat. Primary

DW MCLs

EPA Nat. Secondary DW MCL


SS04-T3-37 GEOCHEM.

(0-3 in.)




AH04-T3-15P

(10-15 ft)

AH04-T3-17P

(10-20 ft)

Aluminum - 0.05 to 0.2 4.17 0.58 8.48 0.53 1.1 0.1 B 0.08 B Antimony 0.006 - <0.0002 <0.0002 <0.0002 0.0003 B <0.0002 0.0015 0.0004 B Arsenic 0.05 / 0.01* - <0.0005 <0.0005 <0.0005 0.0005 B <0.0005 <0.0005 <0.0005 Barium 2 - <0.003 <0.003 <0.003 0.008 B 0.018 0.023 0.024 Beryllium 0.004 - 0.002 B <0.002 0.003 B <0.002 <0.002 <0.002 <0.002 Cadmium 0.005 - <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Cesium - - <0.01 <0.01 0.01 B <0.01 <0.01 <0.01 <0.01 Copper - 1 2.4 0.87 1.67 0.1 1.98 <0.01 <0.01 Iron - 0.3 0.05 0.03 B 0.19 0.35 0.17 <0.01 <0.01 Lead 0.05 - 0.0002 B <0.0001 0.0002 B 0.0013 0.0001 B 0.0004 B 0.0002 B Manganese - 0.05 0.402 0.752 0.796 0.049 1.06 0.065 0.032 Mercury 0.002 - <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 0 H 0 H Selenium 0.05 - 0.002 B 0.001 B 0.002 B <0.001 <0.001 0.003 B 0.004 B Silver - 0.1 <0.005 <0.005 <0.01 0.005 B <0.005 <0.005 <0.005

Thallium 0.002 - <0.00005 <0.00005 <0.00005 <0.00005 <0.00005 0.00022

B 0.00027

B Zinc - 5 0.19 0.14 0.49 0.04 B 0.3 <0.01 <0.01 Paste pH (SU) - 6.5 to 8.5 3.6 4.8 2.8 6.2 4.4 7.7 7.7 Laboratory ID MWH MWH MWH MWH MWH MWH MWH Notes: Source: MWH, 2005a AWQS = ADEQ Numerical Aquifer Water Quality Standards for Drinking Water * EPA Maximum Contamination Level for National Primary Drinking Water Regulations < values are based on MDLs B = Analyte concentration detected at a value between MDL and PQL. The associated value is an estimated quantity. Numbers red, bold and underlined indicate that concentration exceeds AWQS or EPA Maximum Primary Contamination Levels Numbers in italics and underlined indicate that concentration exceeds EPA Maximum Secondary Contamination Levels



Table 6 ABA analytical results for TSF4

Parameter TD08-4 TP4-1 TP4-2 TP4-3 TP4-4 TP4-5 TP4-6 TP4C-1 TP4C-2 TP4C-3 Acid Generation Potential (t CaCO3/Kt) 24.375 24.1 9.1 25.3 13.1 23.4 21.6 8.8 21.9 8.4 Acid Neutralization Potential (t CaCO3/Kt) 16 14 14 14 13 11 14 7 6 7 Paste pH 8.2 7.51 7.85 7.64 7.73 7.32 7.23 7.37 7.71 7.71 Sulfur Residue (%) 0.19 0.04 0.04 0.04 0.07 0.03 0.02 0.05 0.07 0.06 Sulfur Pyritic Sulfide (%) 0.78 0.73 0.25 0.77 0.35 0.72 0.67 0.23 0.63 0.21 Sulfur Sulfate (%) 0.05 0.11 0.06 0.19 0.1 0.11 0.04 0.08 0.18 0.16 Sulfur Total (%) 1.02 0.88 0.35 1 0.52 0.86 0.73 0.36 0.88 0.43 NNP = ANP - AGP -8.375 -10.1 4.9 -11.3 -0.1 -12.4 -7.6 -1.8 -15.9 -1.4 NPR = ANP / AGP 0.66 0.58 1.54 0.55 0.99 0.47 0.65 0.80 0.27 0.83 AGP (% Sulfur Pyritic * 31.25) 24.38 22.81 7.81 24.06 10.94 22.50 20.94 7.19 19.69 6.56 NPR - using Sulfur Pyritic (ANP / revised AGP) 0.66 0.61 1.79 0.58 1.19 0.49 0.67 0.97 0.30 1.07

Initial Assessment (NNP >= 20) No No No No No No No No No No Step 1 (NPR >= 3) No No No No No No No No No No Step 2 (NPR - using Sulfur Pyritic > 3:1) No No No No No No No No No No

Source WMC 2008 Schafer &

Assoc. Schafer &

Assoc. Schafer &

Assoc. Schafer &

Assoc. Schafer &

Assoc. Schafer &

Assoc. Schafer &

Assoc. Schafer &

Assoc. Schafer &

Assoc.

Parameter TP4C-4 TP4C-5 TP4C-6 SS04-T4-55 GEOCHEM (0-12 in.)




Acid Generation Potential (t CaCO3/Kt) 12.5 5 5.9 52 12 8 13 Acid Neutralization Potential (t CaCO3/Kt) 9 8 9 14 14 2 16 Net Acid Generation (Kg H2SO4/t) NAG pH Paste pH 7.65 7.75 7.77 6.9 7.5 3.5 7.2 Sulfur Residue (%) 0.07 0.06 0.06 0.42 0.13 0.08 B 0.21 Sulfur Pyritic Sulfide (%) 0.33 0.1 0.13 1.13 0.16 0.02 B 0.14 Sulfur Sulfate (%) 0.04 0.06 0.02 0.11 0.08 B 0.16 0.08 B Sulfur Total (%) 0.44 0.22 0.21 1.66 0.37 0.26 0.43 NNP = ANP - AGP -3.5 3 3.1 -38 2 -6 3 NPR = ANP / AGP 0.72 1.60 1.53 0.27 1.17 0.25 1.23 AGP (% Sulfur Pyritic * 31.25) 10.31 3.13 4.06 35.31 5.00 0.63 4.38 NPR - using Sulfur Pyritic (ANP / revised AGP) 0.87 2.56 2.22 0.40 2.80 3.20 3.66

Initial Assessment (NNP >= 20) No No No No No No No Step 1 (NPR >= 3) No No No No No No No Step 2 (NPR - using Sulfur Pyritic > 3:1) No No No No No Yes Yes

Source Schafer & Assoc.

Schafer & Assoc.

Schafer & Assoc. MWH MWH MWH MWH



Table 6 TSF4 ABA analytical results (continued)

Parameter SS04-T4-59

GEOCHEM (0-12 in.)


AH04-T4-24P (10-20 ft)

DH04-T4-25P (20-25 ft)

AHO4-T4-27P (45-50 ft)


SS04-T4-48 GEOCHEM

(0-2 in.)

SS04-T4-49 GEOCHEM

(0-3 in.)

SS04-T4-50 GEOCHEM

(0-6 in.)


SS04-T4-52 GEOCHEM

(0-3 in.) Acid Generation Potential (t CaCO3/Kt) 19 39 33 30 52 38 71 46 55 31 41 Acid Neutralization Potential (t CaCO3/Kt) 8 3 18 8 5 21 <1 7 18 25 <1 Paste pH 5.1 4 7.5 7.9 7.5 7.6 3.6 4.3 7.5 7.8 2.6 Sulfur Residue (%) 0.3 0.26 0.17 0.34 0.53 0.11 0.16 0.24 0.11 0.13 0.17 Sulfur Pyritic Sulfide (%) 0.12 0.07 B 0.88 0.52 1 0.87 0.36 0.38 0.83 0.66 0.09 B Sulfur Sulfate (%) 0.18 0.93 <0.01 0.09 B 0.12 0.25 1.75 0.85 0.81 0.2 1.05 Sulfur Total (%) 0.6 1.26 1.05 0.95 1.65 1.23 2.27 1.47 1.75 0.99 1.31 NNP = ANP - AGP -11 -36 -15 -22 -47 -17 -70.5 -39 -37 -6 -40.5 NPR = ANP / AGP 0.42 0.08 0.55 0.27 0.10 0.55 0.01 0.15 0.33 0.81 0.01 AGP (% Sulfur Pyritic * 31.25) 3.75 2.19 27.50 16.25 31.25 27.19 11.25 11.88 25.94 20.63 2.81 NPR - using Sulfur Pyritic (ANP / revised AGP) 2.13 1.37 0.65 0.49 0.16 0.77 0.04 0.59 0.69 1.21 0.18

Initial Assessment (NNP >= 20) No No No No No No No No No No No Step 1 (NPR >= 3) No No No No No No No No No No No Step 2 (NPR - using Sulfur Pyritic > 3:1) No No No No No No No No No No No Source MWH MWH MWH MWH MWH MWH MWH MWH MWH MWH MWH

Parameter SS04-T4-53

GEOCHEM (0-6 in.)


AH04-T4-22P (10-20 ft)

AH04-T4-23P (10-20 ft)

Acid Generation Potential (t CaCO3/Kt) 42 32 33 32 Acid Neutralization Potential (t CaCO3/Kt) <1 <1 17 23 Paste pH 3.7 2.9 7.7 7.8 Sulfur Residue (%) 0.23 0.2 0.18 0.2 Sulfur Pyritic Sulfide (%) 0.45 0.33 0.84 0.81 Sulfur Sulfate (%) 0.65 0.5 0.02 B <0.05 Sulfur Total (%) 1.33 1.03 1.04 1.01 NNP = ANP - AGP -41.5 -31.5 -16 -9 NPR = ANP / AGP 0.01 0.02 0.52 0.72 AGP (% Sulfur Pyritic * 31.25) 14.06 10.31 26.25 25.31 NPR - using Sulfur Pyritic (ANP / revised AGP) 0.04 0.65 0.65 0.91

Initial Assessment (NNP >= 20) No No No No Step 1 (NPR >= 3) No No No No Step 2 (NPR - using Sulfur Pyritic > 3:1) No No No No Source MWH MWH MWH MWH

Notes: Schafer & Assoc. = Geochemical Evaluation of the Magma Copper Company Pinto Valley Mine (1995) Initial Assessment: Yes = NNP >=20 potentially acid neutralizing, No = NNP<20 uncertain or potentially acid generating MWH = BHP Copper Inc. Pinto Valley Mine Site Characterization Report (2005a) Step 1: Yes = NPR >=3 potentially acid neutralizing, No = NPR <3 uncertain or potentially acid generating WMC = WMC 2008 Step 2: Yes = NPR - using Sulfur Pyritic >=3 potentially acid neutralizing, No = NPR - using Sulfur Pyritic <3 uncertain or potentially acid generating B = Analyte concentration detected at a value between MDL and PQL. The associated value is an estimated quantity.



Table 7 Total metals analytical results for TSF4

Parameter (mg/Kg)

Non- residential

SRL GPL Global

Abundance SS04-T4-47 GEOCHEM (0-10 in.)

SS04-T4-48 GEOCHEM

(0-2 in.)

SS04-T4-49 GEOCHEM

(0-3 in.)




Aluminum 920000 - 82300 5690 9300 3550 3130 3000 2060 Antimony 410 35 0.2 0.1 B 0.1 B <0.1 0.2 B 0.2 B 0.1 B Arsenic 10 290 1.7 1 B 1.6 0.6 B 0.5 B 1.4 0.3 B Barium 170000 12000 425 117 127 29 19.7 241 158 Beryllium 1900 23 2.4 0.6 B 1.1 0.3 B 0.5 B 0.5 B <0.2 Cadmium 510 29 0.1 0.7 B 1.4 B 0.5 U 0.7 B 0.7 B <0.5 Calcium - - 41000 Cesium - - - 8 13 5 3 B 3 B 2 B Chromium 65 590 126 Cobalt 13000 - 25 Copper 41000 - 60 505 732 859 888 691 505 Iron - - 56300 16000 21600 8810 10300 6090 16000 Lead 800 290 14 5.51 8.37 3.09 11.7 3.54 5.51 Lithium 20000 - 18 Magnesium - - 23300 Manganese 32000 - 950 274 602 172 154 248 274 Mercury 310 12 0.0625 <0.04 H <0.05 H <0.04 H <0.04 H <0.04 H <0.04 H Molybdenum 5100 - 1.1 Nickel 20000 590 84 Phosphorus - - 903.5 Potassium - - 20900 Selenium 5100 290 0.12 1.3 B 2.1 B 1.1 B 1.8 B 1.1 B 1.3 B Silica - - 282000 Silver 5100 - 0.075 <1 <1 <0.5 <1 <1 <1 Sodium - - 23600 Strontium 610000 - 333 Thallium 67 12 0.52 0.14 0.19 0.09 B 0.08 B 0.08 B 0.14 Thorium - - 8.5 Uranium 200 - 1.7 Vanadium 1000 - 120 Zinc 310000 - 70 45 162 35 62 120 45 Laboratory Source MWH MWH MWH MWH MWH MWH Notes: Source: MWH, 2005a GPL = Groundwater Protection Levels, ADEQ, 1999 < values are based on MDLs B = Analyte concentration detected at a value between MDL and PQL. The associated value is an estimated quantity. H = Analysis exceeded method hold time. pH is a field test with an immediate hold time. Numbers in red indicate that concentration exceeds ADEQ Non-residential Soil Remediation Levels Numbers italicized indicate that concentration exceeds ADEQ Groundwater Protection Levels Numbers bold and underlined indicate that concentration is elevated above the global abundance by a factor of 10 or more MWH = BHP Copper Inc. Pinto Valley Mine Site Characterization Report (2005)



Table 8 TSF4 SPLP leachate analytical results



DW MCLs



SS04-T4-48 GEOCHEM

(0-2 in.)

SS04-T4-49 GEOCHEM

(0-3 in.)




AH04-T4-22P (10-20 ft)

AH04-T4-23P (10-20 ft)

AH04-T4-24P (10-20 ft)

DH04-T4-25P (20-25 ft)

AHO4-T4-27P (45-50 ft)

Aluminum - 0.05 to 0.2 0.04 B 43.6 0.48 0.17 B 0.13 B 0.35 0.08 B 0.88 0.06 B 0.2 0.21 Antimony 0.006 - <0.0002 <0.0002 <0.0002 <0.0002 0.0004 B <0.0002 0.0002 B 0.0003 B 0.0003 B 0.0005 B 0.0008 B Arsenic 0.05 / 0.01* - <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 0.0005 B Barium 2 - 0.014 0.01 B 0.012 0.003 B 0.038 0.033 0.016 0.029 0.021 0.027 0.035 Beryllium 0.004 - <0.002 0.016 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 Cadmium 0.005 - <0.005 0.02 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Cesium - - <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 Copper - 1 <0.01 15.2 0.49 <0.01 <0.01 1.54 <0.01 <0.01 <0.01 <0.01 <0.01 Iron - 0.3 <0.01 0.2 0.02 B 0.08 0.02 B 0.03 B <0.01 <0.01 <0.01 0.03 B 0.02 B Lead 0.05 - 0.0001 B 0.001 0.0003 B <0.0001 <0.0001 0.0001 B <0.0001 <0.0001 0.0002 B <0.0001 0.0004 B Manganese - 0.05 0.016 B 20.9 1.45 0.006 B <0.005 0.112 0.026 B 0.01 B 0.05 0.01 B <0.005 Mercury 0.002 - <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 0 0 0 <0.0002 <0.0002 Selenium 0.05 - 0.002 B 0.015 0.001 B 0.001 B 0.002 B <0.001 0.003 B 0.002 B 0.002 B 0.002 B <0.001 Silver - 0.1 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Thallium 0.002 - 0.00005 B 0.00017 B 0.00008 B 0.00005 U 0.00005 U 0.00005 U 0.00018 B 0.00022 B 0.00021 B <0.0001 0.00019 B Zinc - 5 0.01 B 4.78 0.14 0.01 B <0.01 0.04 B <0.01 <0.01 0.03 B <0.01 <0.01 Paste pH (SU) - 6.5 to 8.5 7.6 3.6 4.3 6.9 7.5 3.5 7.7 7.8 7.5 7.9 7.5 Laboratory ID MWH MWH MWH MWH MWH MWH MWH MWH MWH MWH MWH

Notes: Source: MWH, 2005a AWQS = ADEQ Numerical Aquifer Water Quality Standards for Drinking Water * EPA Maximum Contamination Level for National Primary Drinking Water Regulations < values are based on MDLs B = Analyte concentration detected at a value between MDL and PQL. The associated value is an estimated quantity. Numbers red, bold and underlined indicate that concentration exceeds AWQS or EPA Maximum Primary Contamination Levels Numbers in italics and underlined indicate that concentration exceeds EPA Maximum Secondary Contamination Levels



Table 9 ABA analytical results for test tailings

Parameter TAILINGS SOLID (BL-5-17)

TAILINGS SOLID (BL-5-18)

Acid Generation Potential (t CaCO3/Kt) 8.4 16.9 Acid Neutralization Potential (t CaCO3/Kt) 7 11 Net Acid Generation (Kg H2SO4/t) 3 8 NAG pH 4.3 4.4 Paste pH 8.2 8.3 Sulfur Residue (%) <0.01 <0.01 Sulfur Pyritic Sulfide (%) 0.19 0.45 Sulfur Sulfate (%) 0.08 0.09 Sulfur Total (%) 0.27 0.54 NNP = ANP - AGP -1.4 -5.9 NPR = ANP / AGP 0.83 0.65 AGP (% Sulfur Pyritic * 31.25) 5.94 14.06 NPR - using Sulfur Pyritic (ANP / revised AGP) 1.18 0.78 Initial Assessment (NNP >= 20) No No Step 1 (NPR >= 3) No No Step 2 (NPR - using Sulfur Pyritic > 3:1) No No Source ACZ ACZ L22556-01 L22557-01 Notes: ACZ = ACZ Laboratories, Steamboat Springs, Colorado Initial Assessment: Yes = NNP >=20 potentially acid neutralizing, No = NNP<20 uncertain or potentially acid generating Step 1: Yes = NPR >=3 potentially acid neutralizing, No = NPR <3 uncertain or potentially acid generating Step 2: Yes = NPR - using Sulfur Pyritic >=3 potentially acid neutralizing, No = NPR - using Sulfur Pyritic <3 uncertain or potentially acid generating



Table 10 Total metals analytical results for test tailings

Parameter (mg/Kg)

Non- residential

SRL GPL Global

Abundance TAILINGS

SOLID (BL-5-17)

TAILINGS SOLID

(BL-5-18) Aluminum 920000 - 82300 58400 60100 Antimony 410 35 0.2 <5 <5 Arsenic 10 290 1.7 <3 <3 Barium 170000 12000 425 610 510 Beryllium 1900 23 2.4 2.5 2.5 Cadmium 510 29 0.1 <1 <1 Calcium - - 41000 3700 5100 Chromium 65 590 126 10 9 Cobalt 13000 - 25 <50 <50 Copper 41000 - 60 440 490 Iron - - 56300 13000 15000 Lead 800 290 14 21 18 Lithium 20000 - 18 <40 <40 Magnesium - - 23300 4000 5000 Manganese 32000 - 950 290 210 Mercury 310 12 0.0625 <0.04 <0.04 Molybdenum 5100 - 1.1 <100 <100 Nickel 20000 590 84 <40 <40 Phosphorus - - 903.5 600 <500 Potassium - - 20900 53000 48000 Selenium 5100 290 0.12 2 2 Silica - - 282000 701000 688000 Silver 5100 - 0.075 0.7 <0.6 Sodium - - 23600 6000 9000 Strontium 610000 - 333 70 90 Thallium 67 12 0.52 <1 <1 Thorium - - 8.5 20 20 Uranium 200 - 1.7 5 12 Vanadium 1000 - 120 40 40 Zinc 310000 - 70 60 60 Laboratory ACZ ACZ Source L22556-01 L22557-01

Notes: ACZ = ACZ Laboratories, Steamboat Springs, Colorado GPL = Groundwater Protection Levels, ADEQ, 1999 Numbers in red indicate that concentration exceeds ADEQ Non-residential Soil Remediation Levels Numbers italicized indicate that concentration exceeds ADEQ Groundwater Protection Levels Numbers bold and underlined indicate that concentration is elevated above the global abundance by a factor of 10 or more Numbers in italics and underlined indicate that concentration exceeds EPA Maximum Contamination Levels



Table 11 MWMP leachate analytical results for metallurgical test tailings



DW MCLs


TAILINGS SOLIDS COMBINED

Aluminum (MWMT) - 0.05 to 0.2 0.09 Antimony (MWMT) 0.006 - 0.0023 Arsenic (MWMT) 0.05 / 0.01* - <0.0004 Barium (MWMT) 2 - 0.053 Beryllium (MWMT) 0.004 - <0.0001 Cadmium (MWMT) 0.005 - <0.0002 Calcium (MWMT) - - 20.7 Chromium (MWMT) 0.1 - 0.001 Cobalt (MWMT) - - <0.02 Copper (MWMT) - 1 <0.02 Iron (MWMT) - 0.3 <0.04 Lead (MWMT) 0.05 - <0.0002 Lithium (MWMT) - - <0.02 Magnesium (MWMT) - - 2.9 Manganese (MWMT) - 0.05 0.01 Mercury (MWMT) 0.002 - <0.0002 Molybdenum (MWMT) - - 0.07 Nickel (MWMT) 0.1 - <0.02 Phosphorus (MWMT) - - <0.2 Potassium (MWMT) - - 20.7 Selenium (MWMT) 0.05 - 0.0046 Silicon (MWMT) - - 2.3 Silver (MWMT) - 0.1 <0.0001 Sodium (MWMT) - - 5.6 Strontium (MWMT) - - 0.08 Thallium (MWMT) 0.002 - <0.0002 Thorium (MWMT) - - <0.002 Uranium (MWMT) - / 0.03* - 0.0038 Vanadium (MWMT) - - <0.01 Zinc (MWMT) - 5 <0.02 Bicarbonate as CaCO3 - - 47.3 Carbonate as CaCO3 - - <2 Chloride (MWMT) - - 6.3 Fluoride (MWMT) 4 2 1.09 Hydroxide as CaCO3 - - <2 Nitrate/Nitrite as N (MWMT) - - 0.06 pH (units) - 6.5 to 8.5 8.3 Sulfate (MWMT) - 250 40.0 Total Alkalinity - - 47.3 Laboratory ACZ Laboratory ID L22558-01 Notes: AWQS = ADEQ Numerical Aquifer Water Quality Standards for Drinking Water * EPA Maximum Contamination Level for National Primary Drinking Water Regulations < values are based on MDLs Numbers in italics and underlined indicate that concentration exceeds EPA Maximum Contamination Levels



Table 12 Humidity Cell Test parameters measured (MWH, 2006)

Weekly Parameters Acidity Chloride Aluminum Alkalinity Conductivity Iron

Total pH Calcium Bicarbonate Total Dissolved Solids Iron Carbonate Sulfate Magnesium Hydroxide ---- ----

Additional Week 1, 10, 20 and 26 Parameters Antimony Copper Silica Arsenic Lead Sodium Barium Manganese Strontium Beryllium Mercury Thallium Cadmium Nickel Zinc Chromium Potassium Fluoride Cobalt Selenium Nitrate/Nitrite

Table 13 Weekly HCT indicator parameter results for AH04-T4-24 (MWH, 2006)

Week PH SU

Conductivity umhos/cm

TDS mg/L

Sulfate mg/L

Acidity mg/L

Alkalinity mg/L

Aluminum mg/L

Calcium mg/L

Iron mg/L

Magnesium mg/L

1 NA NA NA NA NA NA 0.60 B 100.00 1.20 7.00 B 2 8.4 464 290 180 B <2 12 0.17 B 58.20 0.05 B 4.80 3 8.4 455 270 190 <2 10 4.70 67.00 6.99 5.00 4 8.3 508 300 210 <2 NA 0.03 B 37.40 0.05 2.00 5 8.1 625 410 <500 <2 6 B 1.45 93.00 0.45 9.20 6 8.3 657 450 300 16 <2 0.08 B 83.10 0.12 8.60 7 8.4 661 80 500 <2 9 B 0.04 B 76.50 0.02 B 8.30 8 8.3 606 390 260 7 B <2 0.09 B 59.80 0.08 9.80 9 8.3 483 370 240 9 B 3 B <0.03 65.70 <0.01 5.90 10 8.5 477 300 200 4 B 9 B 0.18 B 59.10 0.08 5.20 11 8.4 405 230 170 2 B 7 B 0.06 B 45.40 0.03 B 4.20 12 8.4 354 210 140 <2 9 B 0.06 B 36.60 0.12 4.10 13 8.4 255 170 230 6 B 11 0.45 25.30 1.42 5.10 14 8.6 197 110 NA <2 NA 0.05 B 19.20 0.12 3.00 15 8.7 137 80 <500 <2 9 B 0.10 B 12.30 0.25 1.90 16 8.7 195 140 70 B <2 12 0.13 B 16.30 0.18 2.80 17 8.7 163 140 60 <2 13 0.08 B 18.60 0.10 B 1.80 B 18 8.7 99 150 60 <2 6 B 0.11 B 12.70 0.08 0.90 B 19 8.6 127 80 40 15 NA 0.09 B 16.30 0.05 B 0.70 B 20 8.4 118 NA <300 38 NA 0.04 B 12.60 0.02 B 1.40 21 8.5 144 90 30 B <2 13 0.26 14.50 0.12 1.20 22 8.5 185 110 50 B 10 B 22 2.00 B 21.70 0.37 1.30 23 9.0 98 60 20 <2 12 0.21 12.60 0.12 0.70 B 24 8.7 99 60 30 B <2 12 0.22 13.60 0.17 1.50 25 8.7 106 NA NA <2 14 0.15 14.50 0.10 1.70 26 8.4 136 90 30 B <2 22 11.70 22.00 11.30 <4



Table 11 Weekly HCT indicator parameter results for AH04-T4-24 (continued)

Week PH Conductivit

TDS Sulfate Acidity Alkalinit

Aluminu

Calcium Iron Magnesiu 1 7.1 NA 320 180 12 <2 4.71 71.00 1.70 4.50

2 7.1 420 270 160 B 20 3 B <0.03 50.30 0.02 B 3.90 3 7.2 404 180 100 B 12 3 B 0.20 B 44.00 0.06 B 6.00 4 7.2 325 180 <100 3 2 B 0.08 B 37.50 0.01 B 4.00 5 7.3 236 100 90 <2 <2 26.10 19.50 8.12 3.60 6 7.8 154 30 NA 13 <2 13.2 29.50 4.12 3.50 7 7.4 150 80 <100 13 NA 0.16 B 13.90 0.09 1.40 8 7.5 115 60 40 B 4 B 3 B 0.20 B 11.90 0.08 0.90 B 9 7.5 103 90 50 9 B 2 B 0.06 10.50 0.03 0.90 10 7.6 85 50 NA 12 4 B 1.79 9.10 2.12 1.00 B 11 7.5 80 30 30 B 6 B NA 0.09 8.00 0.03 0.60 12 7.4 61 40 30 B 11 3 0.18 B 7.30 0.23 0.50 B 13 7.4 51 40 NA <2 3 B 1.20 5.90 0.33 0.50 B 14 7.5 67 50 30 B <2 3 B 0.22 7.90 0.18 0.60 B 15 7.3 43 50 20 B <2 4 B 0.17 B 4.70 0.31 0.30 B 16 7.8 56 90 30 B <2 3 B 0.89 6.80 0.72 0.60 17 7.5 41 70 NA <2 3 B 0.12 B 5.50 0.06 0.40 B 18 7.6 29 50 <10 <2 2 0.11 B 11.00 0.15 1.30 19 8.3 27 330 40 3 B 3 B 0.20 4.10 0.11 0.30 B 20 7.8 35 800 <10 37 NA 6.66 4.70 1.87 0.90 B 21 7.8 26 40 <30 3 B 2 B 0.14 B 2.90 0.11 0.20 B 22 7.3 32 40 <10 <2 <2 0.18 B 4.30 0.08 0.30 B 23 7.4 33 40 <20 5 B 4 B 0.33 6.20 0.32 0.40 B 24 7.4 29 20 <20 <2 2 B 0.28 3.70 0.20 0.30 B 25 7.1 37 30 10 B <2 3 B 0.11 B 4.10 0.07 0.30 B 26 7.9 23 40 10 B <2 5 B <0.20 3.00 B 0.10 B <1.00

Notes: < = Analyte not detected at or above the indicated Method Detection Limit (MDL). B = Analyte detected above the MDL but below the Practical Quantitation Limit (PQL). NA = Sample not analyzed (most often due to insufficient sample volume)



Table 14 Additional week 1, 10, 20, and 26 HCT parameter results for AH04-T4-24

Parameter Units Week 1 Week 10 Week 20 Week 26

Trac

e M

etal

s an

d M

etal

loid

s (D

isso

lved

)

Aluminum mg/L 0.60 B 0.18 B 0.04 B 11.70 Antimony mg/L <0.008 0.0004 B <0.0004 <0.004 Arsenic mg/L <0.01 <0.0005 <0.0005 0.010 B Barium mg/L <0.06 0.013 0.022 0.12 B Beryllium mg/L 0.004 B <0.0001 <0.0001 0.002 B Cadmium mg/L 0.006 B <0.0001 0.0001 B <0.001 Chromium mg/L 0.007 B 0.0003 B <0.0001 0.004 B Cobalt mg/L <0.10 <0.01 <0.01 <0.20 Copper mg/L 0.21 0.0387 0.0051 0.568 Iron mg/L 1.20 0.08 0.02 B 11.30 Lead mg/L 0.033 0.0004 B 0.0001 B 0.036 Manganese mg/L 0.14 B 0.051 0.017 B 0.2 B Mercury mg/L <0.02 <0.0002 <0.0002 <0.001 Nickel mg/L <0.10 <0.01 <0.01 <0.20 Selenium mg/L <0.02 0.003 B 0.003 B <0.01 Strontium mg/L 0.30 B 0.14 0.04 B <0.20 Thallium mg/L 0.005 B <0.0001 <0.0001 0.002 B Zinc mg/L 0.10 B 0.04 B <0.01 0.30 B

Gen

eral

Wat

er Q

ualit

y Pa

ram

eter

s

pH (lab) Units NA 8.5 8.4 8.4 Conductivity @25C umhos/cm NA 477 118 136 Acidity as CaCO3 mg/L NA 4 B 38 <2 Total Alkalinity mg/L NA 9 B NA 22 Bicarbonate as CaCO3 mg/L NA 9 B NA 22 Carbonate as CaCO3 mg/L NA <2 NA <2 Hydroxide as CaCO3 mg/L NA <2 NA <2

Calcium, dissolved mg/L 100 59.1 12.6 22 Magnesium, dissolved mg/L 7 B 5.2 1.4 4 U Potassium, dissolved mg/L 16 11.3 7.2 14 B Sodium, dissolved mg/L 6 4.9 0.8 B <6 Chloride mg/L NA 2 B 2 B <1 Sulfate mg/L NA 200 <300 30 B Nitrate/Nitrite as N mg/L NA 0.07 B NA 0.07 B Fluoride mg/L NA 0.6 <1 0.4 B Silica, dissolved mg/L 3 1.5 0.8 58 Total Dissolved Solids (TDS)

mg/L

NA

300

NA

90



Table 15 2015 Humidity Cell Test TSF4 results

Week

AWQS / EPA Nat. Primary DW MCLs

EPA Nat. Secondary DW

MCL 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Leachate Sample Date 2/10/2015 2/17/2015 2/24/2015 3/3/2015 3/10/2015 3/17/2015 3/24/2015 3/31/2015 4/7/2015 4/14/2015 4/21/2015 4/28/2015 5/5/2015 5/12/2015 5/19/2015 5/26/2015pH - 6.5 to 8.5 9.4 8.7 7.2 7.0 7.2 6.8 6.9 6.7 7.7 7.4 7.5 7.5 7.4 7.1 7.1 6.4Acidity - - <10 <10 <10 <10 <10 <10 12 <10 <10 <10 <10 <10 <10 <10 <10 <10Alkalinity - - 25 34.4 34.0 23.6 24.8 21.6 17.2 15.6 15.1 15.3 15.0 15.0 13.8 13.3 12.5 16.5Aluminum-dissolved - 0.05 to 0.2 0.1 0.06 0.05 0.06 0.07 0.05Antimony-dissolved 0.006 - 0.0009 0.0012 0.0009 0.0007 0.0005 0.0006Arsenic-dissolved 0.05 / 0.01* - <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002Barium-dissolved 2 - <0.003 0.012 0.019 0.018 0.01 0.014Beryllium-dissolved 0.004 - <0.00005 <0.00005 <0.00005 <0.00005 <0.00005 <0.00005Cadmium-dissolved 0.005 - <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001Calcium-dissolved - - 7.8 16.5 18.6 16.2 10 10.1Carbon (total)-dissolved - - 18 12.2 9.9 8.3 6.9 6.4 4.9 4.8 2.9 4.3 3.3 4.5 3.1 3.5 3.8 5.1Chloride - - <0.5 1.5 0.8 0.8 <0.5 0.8Chromium-dissolved 0.1 - <0.001 <0.001 <0.001 <0.001 <0.001 <0.001Copper-dissolved - 1 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01Fluoride-dissolved 4 2 0.7 0.51 0.53 0.42 0.35 0.49Iron-dissolved - 0.3 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02Lead-dissolved 0.05 - 0.0001 <0.0001 <0.0001 0.0003 <0.0001 0.0001Lithium-dissolved - - <0.008 <0.008 <0.008 <0.008 <0.008 <0.008Magnesium-dissolved - - 0.8 2.2 2.3 2.1 1.3 1.3Manganese-dissolved - 0.05 0.014 0.01 0.059 0.061 0.02 0.022Mercury-dissolved 0.002 - <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002Molybdenum-dissolved - - <0.02 0.04 0.04 0.04 0.06 0.07Nickel-dissolved 0.1 - <0.008 <0.008 <0.008 <0.008 <0.008 <0.008Nitrate + Nitrite 10 - 0.23 <0.02 <0.02 <0.02 0.03 0.02Phosphorus-dissolved - - <0.1 <0.1 <0.1 <0.1 0.1 <0.1Potassium-dissolved - - 4.3 9.2 7.5 4.7 2.6 2.4Selenium-dissolved 0.05 - 0.0008 0.0018 0.0014 0.0013 0.0011 0.0011Silicon-dissolved - - 0.8 1.4 1.2 1.0 0.7 0.8Silver-dissolved - 0.1 <0.00005 <0.00005 <0.00005 <0.00005 <0.00005 <0.00005Sodium-dissolved - - 0.8 2.6 2 1.1 0.5 0.4Strontium-dissolved - - 0.01 0.045 0.051 0.041 0.027 0.025Sulfate - 250 4.1 32.3 35.1 34.6 32.7 31.5 24.1 22.0 20.8 23.7 21.7 21.1 19.4 19.7 18.9 19.6Thallium-dissolved 0.002 - <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001Uranium-dissolved - - 0.0007 0.0052 0.0053 0.0045 0.0031 0.0027Vanadium-dissolved - - <0.005 <0.005 <0.005 <0.005 <0.005 <0.005Zinc-dissolved - 5 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01Laboratory ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZLaboratory ID L22741-02 L22741-03 L22741-04 L22741-05 L22741-06 L22741-07 L22741-08 L22741-09 L22741-10 L22741-11 L22741-12 L22741-13 L22741-14 L22741-15 L22741-16 L22741-17



Table 13 2015 Humidity Cell Test TSF4 results (continued)

Week



MCL 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31Leachate Sample Date 6/2/2015 6/9/2015 6/16/2015 6/23/2015 6/30/2015 7/7/2015 7/14/2015 7/21/2015 7/28/2015 8/4/2015 8/11/2015 8/18/2015 8/25/2015 9/1/2015 9/8/2015 9/15/2015pH - 6.5 to 8.5 6.3 6.3 6.2 6.7 6.1 6.2 6.4 6.2 6.4 6.9 6.8 6.7 6.7 6.8 6.9 6.9Acidity - - <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10Alkalinity - - 13.7 12.9 12.9 12.8 11.7 11.1 11.8 11.6 12.1 14.1 12.9 12.8 12.3 17.7 14.3 13.1Aluminum-dissolved - 0.05 to 0.2 0.07 <0.03 0.06 <0.03Antimony-dissolved 0.006 - 0.0005 0.0006 0.0006 0.0009Arsenic-dissolved 0.05 / 0.01* - <0.0002 <0.0002 <0.0002 <0.0002Barium-dissolved 2 - 0.016 0.009 0.015 0.014Beryllium-dissolved 0.004 - <0.00005 <0.00005 <0.00005 <0.00005Cadmium-dissolved 0.005 - <0.0001 <0.0001 <0.0001 <0.0001Calcium-dissolved - - 10.2 7.8 8.7 8.7Carbon (total)-dissolved - - 5.3 3.1 2.4 2.8 3.0 2.5 2.3 2.5 2.6 2.8 2.9 3.1 2.8 4.1 2.9 2.8Chloride - - 0.8 <0.5 <0.5 0.5Chromium-dissolved 0.1 - <0.001 <0.001 <0.001 <0.001Copper-dissolved - 1 0.01 <0.01 <0.01 <0.01Fluoride-dissolved 4 2 0.41 0.39 0.4 0.45Iron-dissolved - 0.3 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02Lead-dissolved 0.05 - 0.0001 <0.0001 <0.0001 0.0002Lithium-dissolved - - <0.008 <0.008 <0.008 <0.008Magnesium-dissolved - - 1 1.2 1.1 1.0Manganese-dissolved - 0.05 0.059 0.036 0.037 0.032Mercury-dissolved 0.002 - 0.0004 <0.0002 <0.0002 <0.0002Molybdenum-dissolved - - 0.07 0.07 0.09 0.08Nickel-dissolved 0.1 - <0.008 <0.008 <0.008 <0.008Nitrate + Nitrite 10 - <0.02 <0.02 <0.02 0.05Phosphorus-dissolved - - <0.1 0.1 <0.1 <0.1Potassium-dissolved - - 1.8 1.4 1.4 1.3Selenium-dissolved 0.05 - 0.0011 0.0009 0.0011 0.0009Silicon-dissolved - - 0.8 0.7 0.8 0.8Silver-dissolved - 0.1 <0.00005 <0.00005 <0.00005 <0.00005Sodium-dissolved - - 0.2 0.2 <0.2 <0.2Strontium-dissolved - - 0.028 0.015 0.02 0.017Sulfate - 250 18.3 18.0 18.3 15.9 15.4 15.8 15.7 13.7 14.7 13.6 12.1 12.5 11.3 14.4 10.5 9.3Thallium-dissolved 0.002 - <0.0001 <0.0001 <0.0001 <0.0001Uranium-dissolved - - 0.0019 0.0021 0.0016 0.0019Vanadium-dissolved - - <0.005 <0.005 <0.005 <0.005Zinc-dissolved - 5 0.03 <0.01 <0.01 <0.01Laboratory ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZLaboratory ID L22741-18 L22741-19 L22741-20 L22741-21 L22741-22 L22741-23 L22741-24 L22741-25 L22741-26 L22741-27 L22741-28 L22741-29 L22741-30 L22741-31 L22741-32 L22741-33




Week



MCL 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47Leachate Sample Date 9/22/2015 9/29/2015 10/6/2015 10/13/2015 10/20/2015 10/27/2015 11/3/2015 11/10/2015 11/17/2015 11/24/2015 12/1/2015 12/8/2015 12/15/2015 12/22/2015 12/29/2015 1/5/2016pH - 6.5 to 8.5 6.9 6.8 6.8 6.8 6.8 6.8 6.8 6.7 6.7 6.7 6.6 6.6 6.6 6.6 6.6 6.6Acidity - - <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10Alkalinity - - 29.3 12.1 11.8 14.1 13 12.2 11.6 12.4 12.5 12.2 13.8 12.0 11.6 11.3 11.4 10.6Aluminum-dissolved - 0.05 to 0.2 0.04 <0.03 <0.03 0.04Antimony-dissolved 0.006 - 0.0007 0.0006 0.0007 0.0004Arsenic-dissolved 0.05 / 0.01* - <0.0002 <0.0002 <0.0002 <0.0002Barium-dissolved 2 - 0.018 0.023 0.017 0.023Beryllium-dissolved 0.004 - <0.00005 <0.00005 <0.00005 <0.00005Cadmium-dissolved 0.005 - <0.0001 <0.0001 <0.0001 <0.0001Calcium-dissolved - - 7.6 7.6 6.8 6.1Carbon (total)-dissolved - - 2.7 2.8 5.7 3.3 2.6 2.4 2.8 2.6 2.5 4.1 4.3 4.0 4.1 4.1 4.1 3.5Chloride - - 0.6 <0.5 <0.5 <0.5Chromium-dissolved 0.1 - <0.001 <0.001 <0.001 <0.001Copper-dissolved - 1 <0.01 <0.01 <0.01 0.01Fluoride-dissolved 4 2 0.43 0.39 0.39 0.32Iron-dissolved - 0.3 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02Lead-dissolved 0.05 - 0.0001 <0.0001 <0.0001 <0.0001Lithium-dissolved - - <0.008 <0.008 <0.008 <0.008Magnesium-dissolved - - 1.0 0.9 0.9 0.7Manganese-dissolved - 0.05 0.035 0.043 0.036 0.047Mercury-dissolved 0.002 - <0.0002 <0.0002 <0.0002 <0.0002Molybdenum-dissolved - - 0.07 0.06 0.05 0.04Nickel-dissolved 0.1 - <0.008 <0.008 <0.008 <0.008Nitrate + Nitrite 10 - <0.02 <0.02 <0.02 <0.02Phosphorus-dissolved - - <0.1 <0.1 <0.1 <0.1Potassium-dissolved - - 1.1 1.1 1.0 0.8Selenium-dissolved 0.05 - 0.0009 0.0009 0.0007 0.0005Silicon-dissolved - - 0.8 0.7 0.6 0.6Silver-dissolved - 0.1 <0.00005 <0.00005 <0.00005 <0.00005Sodium-dissolved - - <0.2 <0.2 <0.2 <0.2Strontium-dissolved - - 0.021 0.021 0.014 0.019Sulfate - 250 10.9 9.3 10.0 10.1 9.1 7.0 7.3 7.3 6.2 5.9 5.5 5.1 4.9 4.5 3.6 4.1Thallium-dissolved 0.002 - <0.0001 0.0001 <0.0001 <0.0001Uranium-dissolved - - 0.0016 0.0013 0.0013 0.001Vanadium-dissolved - - <0.005 <0.005 <0.005 <0.005Zinc-dissolved - 5 <0.01 <0.01 <0.01 <0.01Laboratory ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZ ACZLaboratory ID L22741-34 L22741-35 L22741-36 L22741-37 L22741-38 L22741-39 L22741-40 L22741-41 L22741-42 L22741-43 L22741-44 L22741-45 L22741-46 L22741-47 L22741-48 L22741-49




Notes: AWQS = ADEQ Numerical Aquifer Water Quality Standards for Drinking Water * EPA Maximum Contamination Level for National Primary Drinking Water Regulations < values are based on MDLs B = Analyte concentration detected at a value between MDL and PQL. The associated value is an estimated quantity. Numbers red, bold and underlined indicate that concentration exceeds AWQS or EPA Maximum Contamination Levels Numbers in italics and underlined indicate that concentration exceeds EPA Secondary Contamination Levels

Week



MCL 48 49 50 51 52 53Leachate Sample Date 1/12/2016 1/19/2016 1/26/2016 2/2/2016 2/9/2016 2/16/2016pH - 6.5 to 8.5 6.6 6.6 6.6 6.7 6.6 6.6Acidity - - <10 <10 <10 <10 <10 <10Alkalinity - - 10.2 11.5 11.1 11.6 10.7 10.1Aluminum-dissolved - 0.05 to 0.2 <0.03 <0.03 <0.03Antimony-dissolved 0.006 - 0.0005 0.0004 <0.0004Arsenic-dissolved 0.05 / 0.01* - <0.0002 <0.0002 <0.0002Barium-dissolved 2 - 0.023 0.023 0.024Beryllium-dissolved 0.004 - <0.00005 <0.00005 <0.00005Cadmium-dissolved 0.005 - <0.0001 <0.0001 <0.0001Calcium-dissolved - - 5.5 5.9 5.5Carbon (total)-dissolved - - 3.4 3.7 3.6 3.8 3.6 3.6Chloride - - <0.5 <0.5 0.6Chromium-dissolved 0.1 - <0.001 <0.001 <0.001Copper-dissolved - 1 0.005 <0.01 <0.01Fluoride-dissolved 4 2 0.38 0.37 0.34Iron-dissolved - 0.3 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02Lead-dissolved 0.05 - <0.0001 <0.0001 <0.0001Lithium-dissolved - - <0.008 <0.008 <0.008Magnesium-dissolved - - 0.5 0.7 0.7Manganese-dissolved - 0.05 0.038 0.034 0.032Mercury-dissolved 0.002 - <0.0002 <0.0002 <0.0002Molybdenum-dissolved - - 0.03 0.02 0.02Nickel-dissolved 0.1 - <0.008 <0.008 <0.008Nitrate + Nitrite 10 - 0.04 <0.02 <0.02Phosphorus-dissolved - - <0.1 <0.1 <0.1Potassium-dissolved - - 0.7 0.7 0.6Selenium-dissolved 0.05 - 0.0005 0.0005 0.0005Silicon-dissolved - - 0.5 0.5 0.5Silver-dissolved - 0.1 <0.00005 <0.00005 <0.00005Sodium-dissolved - - <0.2 <0.2 <0.2Strontium-dissolved - - 0.014 0.013 0.014Sulfate - 250 4.6 5.4 4.9 6.2 5.7 5.6Thallium-dissolved 0.002 - <0.0001 <0.0001 <0.0001Uranium-dissolved - - 0.001 0.0011 0.0012Vanadium-dissolved - - <0.005 <0.005 <0.005Zinc-dissolved - 5 <0.01 <0.01 <0.01Laboratory ACZ ACZ ACZ ACZ ACZ ACZLaboratory ID L22741-50 L22741-51 L22741-52 L22741-53 L22741-54 L22741-55



Table 16 Final ABA results following 2015 53-week HCT

Parameter TAILINGS SOLIDS COMBINED-FINAL

1/12/2016 Acid Generation Potential (t CaCO3/Kt) 8.75 Acid Neutralization Potential (t CaCO3/Kt) 9 Acid-Base Potential (calc on Sulfur total) 0.3 Carbon, total (TC) 0.1 Carbon, total inorganic (TIC) 0.1 Carbon, total organic (TOC) <0.1 NAG <1 Neutralization Potential as CaCO3 0.9 pH After Oxidation 8.2 Paste pH 8.2 pH, Saturated Paste 8.7 Solids, Percent 99.7 Sulfur HCl Residue 0.23 Sulfur HNO3 Residue <0.01 Sulfur Organic Residual <0.01 Sulfur Pyritic Sulfide (%) 0.23 Sulfur Sulfate (%) 0.05 Sulfur Total (%) 0.28 Total Sulfur minus Sulfate 0.23 NNP = ANP - AGP 0.25 NPR = ANP / AGP 1.03 AGP (% Sulfur Pyritic * 31.25) 7.19 NPR - using Sulfur Pyritic (ANP / revised AGP) 1.25

Initial Assessment (NNP >= 20) No Step 1 (NPR >= 3) No Step 2 (NPR - using Sulfur Pyritic > 3:1) No Laboratory ACZ Laboratory ID L29235-01



Table 17 Supernatant analytical results


EPA Primary Drinking

Water MCL

EPA Secondary Drinking

Water MCL AWQS RECLAIM

4/9/1993 #4 Tails Water

6/4/1999

No 3 Tailings

Pond 7/13/1994

Tailing Impoundment

3 2/8/2013

Supernatant (Met Test

liquid) 1/12/2015

RECLAIM PV3

3/3/2016

RECLAIM PV3

3/3/2016

Alkalinity as HCO3 46 116 Alkalinity, Total, as CaCO3 116 12.9

Aluminum, Dissolved 0.05 to 0.2 <0.5 0.11

Aluminum, Total 0.05 to 0.2 1.9 <0.05

Antimony, Dissolved 0.006 0.006 <0.05 0.0011 <0.020

Antimony, Total 0.006 0.006 <0.05 <0.05

Arsenic, Dissolved 0.01 0.05 <0.05 0.0003 <0.025

Arsenic, Total 0.01 0.05 <0.05 <0.005 <0.025

Barium, Dissolved 2 2 0.013 0.015

Barium, Total 2 2 0.017 0.094

Beryllium, Dissolved 0.004 0.004 <0.005 <0.00005 <0.0020

Beryllium, Total 0.004 0.004 <0.005 <0.005 <0.0020

Boron, Total 0.1

Cadmium, Dissolved 0.005 0.005 <0.0005 <0.005 <0.0001 <0.00020

Cadmium, Total 0.005 0.005 <0.0005 <0.005 <0.0005 <0.00020

Calcium, Dissolved 380 17.8

Calcium, Total 430 463 591

Chromium, Dissolved 0.1 0.1 <0.01 <0.01 <0.0060

Chromium, Total 0.1 0.1 <0.01 <0.01 <0.0060

Cobalt, Dissolved 0.059 <0.01 <0.0060

Cobalt, Total 0.07 0.017

Copper, Dissolved 1.3* 1 <0.01 <0.02 <0.01 <0.0100

Copper, Total 1.3* 1 0.191 <0.02 <0.01 <0.0100 Cyanide, Total 0.2 0.2 <0.02 <0.01 0.016



Table 15 Supernatant analytical results (continued)



Water MCL




6/4/1999

No 3 Tailings

Pond 7/13/1994

Tailing Impoundment

3 2/8/2013 Supernatant

1/12/2015 RECLAIM

PV3 3/3/2016

RECLAIM PV3 3/3/2016

Iron, Dissolved 0.3 <0.5 <0.02 <0.060 Iron, Total 0.3 1.4 13.2 0.17 Lead, Dissolved 0.015* 0.05 <0.002 <0.05 0.0001 <0.00300 Lead, Total 0.015* 0.05 <0.002 <0.05 <0.002 <0.00300 Lithium, Total 0.03 <0.008 Magnesium, Dissolved 93 2.7

Magnesium, Total 100 34.4 3.46 Manganese, Dissolved 0.05 14 <0.005 0.0097

Manganese, Total 0.05 15 10.1 0.0158 Mercury, Dissolved 0.002 0.002 <0.0002 <0.0002 0.00028 Mercury, Total 0.002 0.002 <0.0002 <0.0002 <0.0002 0.0008 Molybdenum, Total 0.18 0.08 Nickel, Dissolved 0.1 <0.25 <0.008 <0.0100 Nickel, Total 0.1 0.14 <0.02 <0.0100 Phosphorus, dissolved <0.1

Potassium, Dissolved 24 13.9 Potassium, Total 23 16 Selenium, Dissolved 0.05 0.05 <0.06 0.0060 0.103 Selenium, Total 0.05 0.05 <0.06 <0.005 0.0965 Silicon, dissolved 2.1 Silver, Total 0.1 <0.01 <0.0005 Sodium, Dissolved 110 8.4 Sodium, Total 90 126 Strontium, Total 1.92 0.059



Table 15 Tailings reclaim water (supernatant) analytical results (continued)

Parameter (mg/L unless

noted)


Water MCL




6/4/1999

No 3 Tailings

Pond 7/13/1994

Tailing Impoundment 3

2/8/2013 Supernatant

1/12/2015 RECLAIM

PV3 3/3/2016

RECLAIM PV3

3/3/2016

Thallium, Dissolved 0.002 0.002 <0.05 <0.0001 Thallium, Total 0.002 0.002 <0.05 <0.005 Tin, Total <0.03 Uranium, dissolved 0.03 0.0026 Vanadium, Total <0.01 Zinc, Dissolved 5 <0.01 <0.05 <0.01 <0.010 Zinc, Total 5 0.026 <0.05 0.119 <0.010 Carbonate as CaCO3 <5 <2

Chloride 250 78 72 7.1 Fluoride, Dissolved 4 2 4 4.3 11.7 11.10 6.55 Fluoride, Total 4 2 4 0.42 Hardness, Total as CaCO3 1570 1300 1490

Nitrate + Nitrite, as Nitrogen 10 4.2 0.10 5.82

Nitrate as Nitrogen 10 10 3.8 <0.06 Nitrite as Nitrogen 1 1 0.36 <0.05 pH Lab (su) 6.5 to 8.5 10 7.2 7.7 Specific Conductance Field (umho/cm)

2970

Specific Conductance Lab (umho/cm)

3030

Sulfate 1600 1700 1400 1870 43.2 1540 Cation & Anion Sum, Total In Water (meq/L)

71.549 66.4392

Cation Anion Balance (%) 9.1 0.95



Table 15 Tailings reclaim water (supernatant) analytical results (continued)



Water MCL




6/4/1999

No 3 Tailings

Pond 7/13/1994

Tailing Impoundment 3

2/8/2013

Met Test Supernatant

1/12/2015 RECLAIM 3/3/2016

RECLAIM 3/3/2016

Sum of Anions, Total (meq/L) 39 33.5

Sum of Cations, Total (meq/L) 32.5 32.9

Total Dissolved Solids 500 2900 2500 2590 Total Petroleum Hydrocarbons <0.35

Total Suspended Solids 50 11 Turbidity Lab (NTU) 72 Benzene 0.005 0.005 <0.0005 Ethylbenzene 0.7 0.7 <0.0005 Gross Alpha, Total (pCi/L) 15 15 <23.7 5±0.5

Toluene 1 1 0.0033 Radium 226, Total (pCi/L) 5 5 <0.25

Radium 228, Total (pCi/L) 5 5 <0.67

Laboratory ATI DMA ADOH SVL ACZ SVL Test America

Laboratory ID - PIF00306 - W3B0198-01 L22554 W6C0094 550-59670-1

Notes: MCL - Maximum Contaminant Level, highest level of a contaminant that is allowed in drinking water AWQS = ADEQ Numerical Aquifer Water Quality Standards for Drinking Water * Action Level, lead and copper are regulated by a treatment technique that requires systems to control the corrosiveness of their water. If more than 10% of tap water samples exceed the action level, water systems must take additional steps. For copper, the action level is 1.3 mg/L, and for lead is 0.015 mg/L < values are based on MDLs bold and underlined exceeds EPA Primary Drinking Water MCL and AWQS italics exceeds EPA Maximum Contamination Levels



Figures



Figure 1 Site map showing tailing impoundments (Google Earth, 2016)



Figure 2 Location map for TP (test pit) from TSF3 (Schafer and Associates, 1995)



Figure 3 Location map for TP (test pit) from TSF4 (Schafer and Associates, 1995)



Figure 4 Location map for MWH (2005) surface samples (SS) from TSF3



Figure 5 Location map for surface samples (SS) from TSF4 (MWH, 2005)



Figure 6 Locations of drillhole samples used for 2015 metallurgical test of future ore and tailings. Approximate LOM pit shell (upper, 45’ contours) and September 2014 pit topography (lower, 10’ contours).



Figure 7 TSF3, TSF4, and Test Tailings ABA analysis



Figure 8 TSF3, TSF4, and Test Tailings Total Metals analysis



Figure 9 TSF3 and TSF4 SPLP analyses



Figure 10 Comparison of historic ABA analysis and metallurgical test tailings



Figure 11 Comparison of historic total metals analysis and metallurgical test tailings



Figure 12 Comparison of historic SPLP and MWMP analyses and metallurgical test tailings



Figure 13 Liberated grains of pyrite and chalcopyrite in the tailings (Test 18, first cleaner tails) Cp=chalcopyrite; Py=pyrite; Gn=gangue) (Base Met, 2015)

Figure 14 Chalcopyrite (cp) and pyrite (py) encapsulated in silicate gangue (gn) (Base Met, 2015)



Figure 15 HCT results for pH from TSF4 (MWH, 2006)

Figure 16 HCT results for specific conductivity – 26 week test (MWH, 2006)



Figure 17 HCT results for sulfate – 26 week test (MWH, 2006)

Figure 18 HCT results for total dissolved solids – 26 week test (MWH, 2006)



Figure 19 HCT results for calcium – 26 week test (MWH, 2006)

Figure 20 HCT results for cumulative sulfate release – 26 week test (MWH, 2006)



Figure 21 HCT results for alkalinity – 26 week test (MWH, 2006)

Figure 22 HCT results for pH of metallurgical test tailings – 53 week test (SRK, 2016)



Figure 23 HCT results for sulfate from metallurgical test tailings – 53 week test (SRK, 2016)

Figure 24 Depletion of carbon and sulfur in metallurgical test tailings – 53 week test (SRK, 2016)

memo - pinto valley mine eis• mwmp characterization per astm method e2242 (astm, 2012), with...

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