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SETTLING DEFENDANTS BMFOU QUARTERLY REPORT CONSENT DECREE FOR THE

BUTTE MINE FLOODING SITE CD, CV 02-35 Bu-RFC REMEDIAL ACTION – IMPLEMENTATION OF THE REMEDY

FIRST QUARTER, 2017 The Settling Defendants1 continue to implement the remedial action requirements of the Butte Mine Flooding Operable Unit (BMFOU) specified in the Statement of Work to the Consent Decree (CD). This report summarizes those activities conducted during the first quarter of 2017 as required under Section X. Reporting Requirements, Paragraphs 31 and 35 of the CD. The headings a) through g) in the following report sections correspond to the categories identified in Paragraph 31. The sections captioned h) Issues Encountered and i) Other have been added at the request of the U.S. Environmental Protection Agency (EPA).

a) Actions taken toward achieving compliance with the Consent Decree

To achieve compliance with the CD, the Settling Defendants conducted remedial action activities under the seven components identified in the Statement of Work for Remedial Design/Remedial Action (“SOW”) which is Appendix C of the CD. These seven components and the remedial action activities undertaken by the Settling Defendants (hereinafter referred to as “SDs”) in the first quarter of this year include:

1. Monitoring Program - The Montana Bureau of Mines and Geology (MBMG)

conducted monitoring activities as required by the SOW with the exception of the semi-annual Berkeley Pit water quality sampling program, and monthly sampling of the Granite Mountain Mine shaft. Water level measurements of the Granite Mountain Mine shaft have not been completed since July 2016 due to an obstruction in the shaft at the depth of 420 feet and safety concerns with accessing the area around the shaft. The MBMG is currently working with the SDs to develop a plan to find an alternative means for measuring the water level. Installation of a pressure transducer is being considered with a direct read cable to avoid entering the immediate area around the shaft on a monthly basis. In addition, MBMG is also developing a plan to install pressure transducers with direct read cables to the Anselmo, Kelley, Pilot Butte, Lexington, Marget Ann, and Steward mine shafts in Q2 2017. A rotational slump of the highwall in the southeast sector of the Berkeley Pit occurred on February 8, 2013. This slope failure and the potential of continuing slope

1 The term Settling Defendants as used in this report collectively refers to Atlantic Richfield Company, Montana Resources, Inc., Montana Resources LLP, and Dennis Washington.

instability in the eastern sector of the Berkeley Pit has created a safety issue for people entering the Berkeley Pit including people who enter the Pit to collect water quality samples and conduct other components of the Remedial Action. At the request of the Agencies, the SDs are evaluating the necessity for near-term water quality sampling of the Berkeley Pit and potential safe, alternative sampling methods and migratory waterfowl mitigation efforts. The SDs entered into an agreement with Montana Tech to investigate and construct a remotely operated “drone” sampling platform for the Berkeley Pit. Field testing of this technology is currently taking place and included a field trial on the Berkeley Pit on March 29, 2017. During the field trial, the purge line wrapped around one of the boat motor propellers and the trial was aborted. A second trial is scheduled for Q2 2017. During Q1 2017, no significant slope failures occurred within the Berkeley Pit.

Montana Resources LLP (MR) provided access to MBMG personnel to conduct monitoring. In addition to regular monitoring, after the November 28, 2016, waterfowl event, the U.S. Fish and Wildlife Service (USFWS) requested a sample of Berkeley Pit surface water to assist with evaluating water toxicity. A grab surface water sample was collected by MBMG on December 7, 2016. Results of the surface sample were reported to the Agencies by MBMG via December 8 and 16, 2016, emails as well as included in the MBMG Butte Mine Flooding Consent Decree 02-350BU-SHE 2016-Data Summary (MBMG, 2017) submitted to the Agencies on February 2, 2017.

2. Public Education and Involvement – The SDs are represented on the Berkeley Pit Public Education Committee which directs the publication of the PITWatch and the website www.PITWATCH.ORG. These are the primary vehicles for educating the public about BMFOU status and activities. A PITWatch meeting was held on March 13, 2017, in which the SDs participated. The PITWATCH committee, with support from the SDs, is developing several articles to be published in Q2 of 2017.

In addition, local waterfowl experts in the Butte area agreed to form the Berkeley Pit Migratory Waterfowl Mitigation Advisory Group (Waterfowl Advisory Group) to provide advice on ways to discourage birds from landing in or remaining in the Berkeley Pit. The Waterfowl Advisory Group met three times in the first quarter of 2017, on February 2 and 16, and March 2, 2017. The SDs are currently working with the Waterfowl Advisory Group to evaluate additional waterfowl mitigation measures and update the Waterfowl Mitigation Plan.

http://www.pitwatch.org/

On March 29, 2017, Montana Tech attempted a field test of the “drone” sampling platform on the Berkeley Pit. As part of this effort, Montana Tech and MR worked with local media outlets to cover the event.

3. Horseshoe Bend (“HSB”) Inflow Control – The SOW requires integration of the HSB flow into mine operations and/or release of treated water into Silver Bow Creek. Since the issuance of the Record of Decision (ROD) in 1994 and integration of treated HSB water into the mining and milling process on April 15, 1996, the flow has become an integral part of the water balance for efficient active mining and milling operations at MR. Treated HSB Water Treatment Plant (WTP) water has been integrated into MR’s milling water circuit since the HSB WTP was commissioned in November 2003.

During the quarter, approximately 653,400 gallons of HSB flow was bypassed to the Berkeley Pit from February 27, 2017, to March 1, 2017 due to muddler pump maintenance. This volume is approximately less than 0.2% of the total treated volume for the quarter at 405,000,000 gallons. Significant maintenance activities completed during the quarter include:

• New float installed in polymer hot water storage tank. • Mercury vapor lights replaced with LED lights throughout plant. • Access door installed in south slurry tank. • Valves on south slurry tank moved to eliminate plugging due to dead legs

of pipe where material built up. • Two new heaters installed in the alkalization room. • South slurry tank descaled.

Control of groundwater levels in the vicinity of the HSB WTP continued. Engineering controls operated during the first quarter and regulated the groundwater level in the area of the HSB WTP. First quarter 2017 reporting of these activities is included in the Horseshoe Bend Water Treatment Plant Groundwater Level Reduction Project Quarterly Report included as Attachment 1 to this report.

4. HSB Water Treatment Plant Upgrade/Sludge Repository – The SDs have initiated the HSB WTP Remedial Action Adequacy Review (RAAR) to ensure that ongoing and future remedial activities will meet the requirements of the CD. The preliminary draft schedule for the BMFOU RAAR was submitted on June 30, 2014, and approved by the Agencies on September 11, 2014. The latest RAAR contractor-updated schedule was provided in the previous BMFOU quarterly report. The SDs are

currently working with the RAAR “Supervising Contractor” to develop an updated draft schedule. The comprehensive list of activities in the schedule was identified to meet the milestones required in the CD and also to complete important precursor activities to meet those requirements to ensure continued protectiveness of the remedy. The scope of work for the RAAR was prepared to evaluate four primary tasks with appropriate subtasks. The primary tasks in the RAAR include:

Task 1. HSB WTP Operations and Maintenance (O&M) Optimization: • Short-term optimization. • Long-term optimization. • Optimization with various source water quality and quantity.

Task 2. BMFOU Site-wide Water Balance Study: • Base case – current and historical conditions. • Future conditions – predictive analysis. • Integrate water quality into predictive water balance.

Task 3. Potential Pilot Studies Evaluation: • Sludge disposal alternatives. • Alternate influent sources. • Alternative treatment enhancements.

Task 4. Technical Memorandum Preparation.

The SDs selected Golder as the RAAR consulting firm in May 2015 and provided a statement of qualifications to the Agencies of the firm selected. On May 20, 2015, the Agencies approved Golder as a “Supervising Contractor” pursuant to the CD, Section VI. PERFORMANCE OF THE WORK BY THE SETTLING DEFENDANTS, Paragraph 10, Selection of Supervising Contractors. On April 20, 2016, a Final BMFOU RAAR Horseshoe Bend Water Treatment Plan Short-term Optimization Work Plan (Golder, 2016) was submitted to the Agencies. The SDs anticipate submitting the Draft HSB WTP Short-Term Optimization Review Technical Memorandum to the agencies in Q2 or Q3 2017. On September 2, 2016, the BMFOU RAAR Draft Final Water Balance Work Plan (SDs, 2016) was submitted to the Agencies. Comments from the Agencies have been received. It is anticipated that responses to Agency comments and the BMFOU RAAR Final Water Balance Work Plan will be provided Q2 2017.

The Explanation of Significant Differences, Appendix A to the CD, allows for placement of sludge into the Berkeley Pit. During Q1, all the sludge generated by the HSB WTP was placed into the Berkeley Pit (see Table in Section 7b). The evaluation of sludge disposal alternatives is also included as an activity on the BMFOU RAAR schedule.

5. West Camp System – During the first quarter of 2017, approximately 18.5 million gallons of water were pumped from the West Camp pump station (WCP-1) to the Lower Area One (LAO) for treatment in the Butte Treatment Lagoons (BTL) system. Operators of the BTL maintained normal operating levels the entire quarter. The water level at the end of the quarter was 5,420.96 (National Geodetic Vertical Datum [NGVD] 29), below the West Camp Critical Water Level of 5435 (NGVD 29).

6. Waterfowl Mitigation – During the reporting period, the SDs conducted monitoring, active and passive hazing efforts, and reporting as required by the Berkeley Pit Migratory Waterfowl Mitigation Plan (Exhibit 5 to the CD), but did not perform any manned on-water activities due to the rotational slump of the highwall in the southeast sector of the Berkeley Pit as discussed previously. The SDs continued to perform waterfowl mitigation efforts under the variance from this requirement of the Berkeley Pit Waterfowl Mitigation Plan.

A major migratory waterfowl event occurred on the Berkeley Pit on November 28, 2016, where a large number of migrating “light” geese landed on the Berkeley Pit. In response to this event, the SDs have either initiated or completed the following in Q1 2017:

• Prepared the Proposed Additional Bird Mitigation and Hazing Techniques for the Berkeley Pit Spring 2017 (SDs, 2017) and submitted to the Agencies on February 20, 2017. The Agencies subsequently approved the document on March 3, 2017. The SDs are currently working to implement interim measures described in the document.

• The SDs continue to investigate the Nov. 28, 2016, incident and have retained waterfowl experts to support this effort. Technical memos with expert comments and recommendations will be provided to the agencies when the memos are complete.

• On February 2, 2017, the Agencies issued a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) 104e Request for Information regarding the November 28, 2016, event. In Q1 2017, the SDs worked to prepare a joint response to the request, which is anticipated to be submitted to the Agencies on April 14, 2017.

The SDs submitted the November and December 2016 Berkeley Pit Migratory Waterfowl Mitigation Monthly Report (SDs, 2017) to the Agencies on February 28, 2017, which included the observation and hazing logs as attachments to the report. Please see these reports for a detailed description of the mitigation efforts.

7. Institutional Controls – Full SD compliance with this component of the Remedial Action (RA) SOW was completed by funding provided in 2002 by the SDs past and future cost cash out provisions of the CD. The Butte Alluvial and Bedrock Controlled Ground Water Area (“BABCGWA”) was established by the Montana Department of Natural Resources and Conservation (DNRC) in October 2009 with Butte-Silver Bow as the petitioner. Implementation and monitoring of the BABCGWA was assigned to the MBMG and funding came from the SDs cash out amount that was provided in 2002. The outer perimeter of the area was determined and covered approximately 8.11 square miles. Please see the Butte Mine Flooding Operable Unit, Water-Level Monitoring and Water-Quality Sampling, 2012 Consent Decree Update, 1982-2012 (MBMG, 2013) and consult Mr. Terrence E. Duaime, Project Manager of the MBMG for more detailed information. Access - The SDs have fully complied with the CD requirement to provide access to the Agencies. The SDs provided access to the MBMG personnel to conduct monitoring.

b) Summary of all results of sampling and tests and all other data generated in the previous quarter

The following table summarizes the performance of the HSB WTP in Quarter 1, 2017, and in total for the year:

Period Influent (MG)

HSB Plant

Water2 (MG)

Sludge Wasted (MG)

Lime Delivered

(tons)

Average Influent

Flow (MGD)

Average Lime Usage

(mg/L)

Quarter 1 405 410 17 3,901 4.6 2,306 Quarter 2 Quarter 3 Quarter 4

Total 405 410 17 3,901 4.6 2306 MG: millions of gallons. MGD: millions of gallons per day. mg/L: milligrams per Liter.

2 The treated HSB water that is used in MR’s milling process as required by the CD will be referred to as “HSB Plant Water” instead of the previously used term “effluent.” This semantics change has been made to distinguish

The HSB WTP water is sampled at multiple locations including the HSB WTP influent, Stage 1 Clarifier overflow (during 2 stage operation), and Plant Water (Mill influent formerly named plant effluent). These data will be used in the RAAR HSB WTP optimization currently ongoing. The testing demonstrates that the current operation of the HSB WTP satisfactorily complies with the requirement of the CD to treat HSB water that is to be incorporated in MR’s milling circuit.

In the vicinity of the HSB WTP, engineering controls associated with groundwater monitoring and dewatering to manage the groundwater elevation continued to operate. The Horseshoe Bend Water Treatment Plant Groundwater Level Reduction Project Quarterly Report is included as Attachment 1 to this report.

c) Identify all work plans and other deliverables required by this Consent Decree

completed and submitted in the previous quarter

The following deliverables required by the CD were completed or submitted in Q1 2017: 1. SD BMFOU Quarterly Report CD for the Butte Mine Flooding Site CD, CV 02-35

Bu-RFC Remedial Action – Implementation of the Remedy Fourth Quarter 2016 (SDs, 2017) was submitted to the Agencies on February 28, 2017.

2. November and December 2016 Berkeley Pit Migratory Waterfowl Mitigation Monthly Report (SDs, 2016) was submitted to the Agencies on February 28, 2017.

3. Proposed Additional Bird Mitigation and Hazing Techniques for the Berkeley Pit Spring 2017 (SDs, 2017) was submitted to the Agencies on February 20, 2017.

4. MBMG BMF Monthly Report BMFOU CD 02-35-BU-SEH Remedial Action-Monitoring Program Contract No. 415008-TO-2 December 2016 (MBMG, 2017) was submitted by MBMG on behalf of the SDs on January 10, 2017.

5. MBMG BMF Monthly Report BMFOU CD 02-35-BU-SEH Remedial Action-Monitoring Program Contract No. 415008-TO-2 January 2017 (MBMG, 2017) was submitted by MBMG on behalf of the SDs on February 10, 2017.

6. MBMG BMF Monthly Report BMFOU CD 02-35-BU-SEH Remedial Action-Monitoring Program Contract No. 415008-TO-2 February 2017 (MBMG, 2017) was submitted by MBMG on behalf of the SDs on March 23, 2017.

7. MBMG Butte Mine Flooding Consent Decree 02-35-BU-SEH 2016-Data Summary (MBMG, 2017) was submitted to the Agencies on February 2, 2017.

8. MBMG 2016 Berkeley Pit Infilling Report (MBMG, 2017) was submitted to the Agencies on January 30, 2017.

between effluent that will be treated to the discharge standards stipulated in the CD SOW and plant water that is treated to standards for inclusion into MR’s milling process.

d) Describe all actions, data collection and implementation or work plans that may be

required under this CD scheduled for the next quarter and provide other information relating to the progress of the work

RA Activity - The RA activity required in this section is congruent with that reported at the beginning of this document and is aligned with the seven general components of the SOW and RA. The inclusion of an eighth component to follow the RAAR required by the SOW has been added as an additional activity for the next quarter. The second quarter 2017 anticipated activity summary is as follows: 1. The Monitoring Program will continue to be implemented during the next quarter,

with the exception of sampling the Berkeley Pit and Granite Mountain Mine shaft. The SDs will continue to provide access, cooperation, and any assistance to the MBMG requested in performing this task. The SDs will continue to pursue safe methods of sampling the Berkeley Pit by progressing the remote sampling platform. The MBMG and the SDs will continue to develop a plan to find alternative means (e.g., direct read pressure transducer) of measuring the groundwater elevation within the Granite Mountain Mine shaft. In addition, MBMG will continue to develop a plan to install pressure transducers with direct read cables to the Anselmo, Kelley, Pilot Butte, Lexington, Marget Ann, and Steward mine shafts in Q2 2017.

2. The SDs will provide information to the Agencies as requested and participate in any

public education meetings or activities that the Agencies deem necessary to fulfill this requirement of the CD.

3. The HSB WTP will continue to operate in the next quarter with the goal of capturing and treating flow emanating from the HSB area. The Inflow Control requirement will continue to be met with the HSB WTP treated water being integrated into the mining and milling operations.

4. Operation of the dewatering system around the HSB WTP will continue. 5. The Draft HSB WTP Short Term Optimization Review Technical Memorandum will

be prepared, and is anticipated for submittal in Q2 or Q3 2017. 6. It is anticipated that SD response to Agency comments regarding the BMFOU RAAR

Draft Final Water Balance Work Plan (SDs, 2016) will be submitted to the Agencies in Q2. The BMFOU RAAR Final Water Balance Work Plan is anticipated to be submitted in Q2 of 2017.

7. Sludge from the HSB WTP will continue to be placed into the Berkeley Pit during the

next quarter. 8. Pumping from WCP-1 will continue to maintain West Camp water levels below the

critical water level. 9. Waterfowl mitigation efforts will be continued as required by the Berkeley Pit

Migratory Waterfowl Mitigation Plan, Exhibit 5 to the CD (with the approved exemption from bi-monthly surface inspections) with frequency of observations commensurate with the migratory season. Monthly reports will continue to be submitted to the Agencies. The SDs continue to investigate the November 28, 2016, waterfowl event and will continue to work with the Waterfowl Advisory Board. The SDs are preparing for the upcoming spring migration season and are implementing the interim measures identified in the Proposed Additional Bird Mitigation and Hazing Techniques for the Berkeley Pit Spring 2017. The SDs will continue a full review and update to the Berkeley Pit Migratory Waterfowl Mitigation Plan, anticipating the document to be submitted prior to fall migration and then finalized following the fall 2017 migration season.

10. The Institutional Controls required by the CD will continue to be met with full access

provided to the Agencies, the MBMG, and all SDs at all reasonable times. MR plans to continue to operate the active mining and milling operation within the stipulations of Section IX. Access and Institutional Controls of the CD.

11. The BMFOU RAAR schedule will be followed and modified, as needed, with

modifications approved by the Agencies. 12. The Fourth Five-Year Review Report for Silver Bow Creek/Butte Area Superfund Site

(EPA, January 2016) was issued by the EPA on August 30, 2016, is currently under review by the SDs.

e) Include information regarding unresolved delays encountered or anticipated that

may affect the future schedule for implementation of the Work.

Unresolved delays include in part, on-water waterfowl mitigation and water quality sampling of the Berkeley Pit due to safety issues. Resumption is contingent upon determination of near term necessity of pit water sampling, additional slope stability monitoring, and risk assessment study or adoption of an alternative sampling monitoring

technique. See the previous discussion in Section a.1 regarding the agreement entered into between the SDs and Montana Tech.

f) Include any modifications to the Remedial Action or Remedial Design Work Plans or other work plans or schedules that SDs have proposed to EPA or that have been approved by the EPA.

The BMFOU RAAR schedule updates are ongoing. The MBMG is not currently monitoring the Granite Mountain shaft due to safety concerns as discussed above.

g) Describe all activities undertaken in support of the Community Relations Plan during the previous quarter and those to be undertaken in the next quarter

Please see the response above in Section a. Actions taken toward achieving compliance with the CD, Subsection 2. Public Education and Involvement for details to the answers to this reporting requirement.

h) Issues encountered

Safety concerns have led to the temporary suspension of water-level monitoring at the Granite Mountain Mine as discussed above. Atlantic Richfield Company and MBMG personnel inspected all mine shaft sites to identify potential future safety issues that may impact the long-term monitoring program. No immediate problems beyond the Granite Mountain site were identified; however, installation of pressure transducers with direct read cables to the Anselmo, Kelley, Pilot Butte, Lexington, Marget Ann, and Steward mine shafts are being planned to increase reliability of monitoring.

i) Other

The following information is included in this report at the request of the Agencies and is not part of the BMFOU RA. MR continued operations during the first quarter in compliance with State-issued permits and the description in the CD that allows for the recovery of ore, crushing, concentration, leaching and the importation of water as needed for mining (CD, Section IX. ACCESS AND INSTITUTIONAL CONTROLS, part 26b., p. 39).

Attachment 2 is a memorandum for Q1 titled Berkeley Pit Slope Stability First Quarter Summary 2017 (MR, 2017) produced by MR’s Engineering Department. The report summarizes activities conducted during the quarter related to monitoring and dewatering

of the alluvium in the Concentrator, Southeast Corner and Pittsmont Sectors of the Berkeley Pit.

Submission of this report does not constitute a statement by Atlantic Richfield Company or MR concerning responsibility between them for any identified tasks or a statement by Atlantic Richfield Company or MR that any specific task is required to comply with any existing agreement.

BMFOU QUARTERLY REPORT

Q1 2017

ATTACHMENT 1:

Horseshoe Bend Water Treatment Plant Groundwater Level Reduction Project Quarterly Report

A Washington Company

Montana Resources, LLP 600 Shields Ave. Butte, Montana USA 59701 (406) 496-3200 (406) 723-9542 fax www.montanaresources.com

MEMORANDUM TO: Mark Thompson

FROM: Amanda Griffith

DATE: May 9, 2017

SUBJECT: HsBWTP GWL Reduction-2017 1st Quarter Summary

Overview

The Horseshoe Bend groundwater dewatering system was operated continuously through the first quarter of 2017. Individual wells were shut down for less than ten minutes apiece to reconnect outgoing pipes following weekly manual flow measurements. Flow rates can be seen in Table 1. Locations of the wells around the plant can be seen in Figure 1. The pumps in H14-4, H14-5, and H14-6 were not operated during the quarter so that their effectiveness in the dewatering network could be evaluated. Water levels and pumping rates were monitored weekly to determine their effect on the dewatering of the area. The water levels in the pumping and monitor wells remained relatively steady over the quarter.

The water level in monitor well H14-3 increased by 0.20 feet over the quarter. The water level in monitor well H15-9 increased 0.14 feet over the quarter. The water level in monitor well H16-13 increased 12.06 feet over the quarter. This apparent dramatic increase was due to an instrumentation error. The water in monitor well H16-14 decreased 0.01 feet. Changes in water level over the first quarter can be seen in Table 2.

No new monitor wells were installed during the first quarter. No maintenance was performed on existing wells. The Static Water Level (SWL) and Pumping Water Level (PWL) elevations of all wells can be seen in Table 2. A graphical plot of the elevations can be seen in Figure 2.

HsB

WT

P GW

L R

eduction-2017 1st Quarter Sum

mary

Page 2 of 5

A Washington Com

pany

1/10/2017 1/18/2017 1/25/2017 1/30/2017 2/9/2017 2/16/2017 3/2/2017 3/9/2017 3/16/2017 3/23/2017 3/29/2017

Pump Average Average Average Average Average Average Average Average Average Average AverageH14-1 39.2 43.4 39.7 43.8 46.5 45.1 39.8 39.8 43.2 40.0 39.9 *H14-2 14.2 14.0 13.4 14.1 17.5 13.7 14.6 15.8 13.4 15.5 14.3 *H14-4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0H14-5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0H14-6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0H15-7 2.9 2.7 2.6 2.6 2.9 2.6 2.8 2.9 2.8 2.9 3.0H15-8 11.5 11.4 11.3 11.3 10.9 11.4 11.5 11.8 11.6 11.5 11.4 *H15-10 4.3 4.3 4.4 4.3 4.2 3.8 4.3 4.4 4.6 4.1 4.3 *H15-11 8.0 7.5 7.4 7.4 7.1 7.2 7.2 7.6 7.0 7.1 7.1 *H15-12 9.6 9.6 9.5 9.5 9.8 9.7 9.6 10.1 10.1 10.7 11.5 *

* indicates an overall decrease in flow+ indicates an overall increase in flow

Table 1. Pumping rates for HsBWTP dewatering wells for the 1st quarter of 2017.

HsB

WT

P GW

L R


mary

Page 3 of 5

A Washington Com

pany

Figure 1. Site map of HsBWTP and surrounding dewatering and monitor wells.

HsB

WT

P GW

L R


mary

Page 4 of 5

A Washington Com

pany

5,490

5,500

5,510

5,520

5,530

5,540

5,550

5,560

5,570

1/1/

2017

1/31

/201

7

3/2/

2017

4/1/

2017

H2O

ELE

VATI

ON

S (U

SGS

COO

RDIN

ATES

)

DATE

1st Quarter 2017 HsBWTP Water Levels

H14-1

H14-2

H14-3

H14-4

H14-5

H14-6

H15-7

H15-8

H15-9

H15-10

H15-11

H15-12

H16-13

H16-14

Figure 2. HsBWTP dewatering and monitor well levels for 1st quarter of 2017.

HsBWTP GWL Reduction-2017 1st Quarter Summary Page 5 of 5


Well

3/30/2017 Water

elevation (USGS ft)

3/30/2017 Water

elevation (ACM ft)

Change from 1/1/2017 (ft)

Screened interval (ACM ft)

H14-1* 5536.23 5588.86 -1.62 5562-5582H14-2* 5537.03 5589.66 -0.02 5561-5581H14-3 5524.07 5576.70 0.20 5555-5575

H14-4** 5535.97 5588.60 0.16 5538-5558H14-5** 5499.56 5552.19 0.40 5515-5535H14-6** 5510.35 5562.98 0.41 5535-5555H15-7* 5547.58 5600.21 -0.16 5593-5623H15-8* 5546.32 5598.95 -0.15 5592-5602H15-9 5558.82 5611.45 0.14 5597-5507

H15-10* 5530.22 5582.85 -0.11 5572-5592H15-11* 5535.96 5588.59 -0.18 5576-5596H15-12* 5539.52 5592.15 -0.11 5582-5612H16-13 5558.75 5611.38 12.06 5579-5599H16-14 5547.92 5600.55 -0.01 5579-2289

* Pumping well** No longer pumping

Table 2. Pumping and static water levels of the HsBWTP dewatering and monitor wells 1/1/2017 through 3/30/2017.

BMFOU QUARTERLY REPORT

Q1 2017

ATTACHMENT 2:

Berkeley Pit Slope Stability Quarterly Summaries


Montana Resources, LLP 600 Shields Ave. Butte, Montana USA 59701 (406) 496-3200 (406) 723-9542 fax www.montanaresources.com

MEMORANDUM TO: Stephen Walsh

FROM: Josh Shutey

COPY: Mark Thompson, MR; Tim Hilmo, ARCO/BP

DATE: May 4, 2017

SUBJECT: Berkeley Pit Slope Stability First Quarter Summary 2017

Summary Monitoring of the Berkeley Pit highwall slope stability continued throughout the First Quarter of 2017. The monitoring network is illustrated in Plate I and summarized in Table 1.

Table 1. Berkeley monitoring network First Quarter 2017.

Monitoring The monitoring network was maintained throughout the quarter and repairs, replacements, and adjustments were completed promptly, as needed, to ensure uninterrupted coverage in areas with a high Probability of Instability (POI).

Mon

itor P

oint

s &

Pris

ms

Exte

nsio

met

ers

Incl

inom

eter

s

TDR

Cabl

es

Dew

ater

ing

Pum

ps

Wat

er Le

vels

4 — — 1 — 13 3 — 3 — 55 3 3 — 6 113 — — 4 — 3

BERKELEY PIT HIGHWALL STABILITY

Bird Watch Sector

Concentrator Sector

Southeast Sector

Pittsmont Sector

Berkeley Slope Stability Quarterly Summary Jan - Mar 2017 Page 2 of 7


Three survey points in the Bird Watch Sector were checked weekly and one survey point was checked daily. Survey points in the Southeast Sector and Concentrator Sector were monitored daily. Survey prisms in the Pittsmont Sector were checked Weekly. Wire extensometers in the Concentrator Sector, were checked several times per day. Wire extensometers in the Southeast Sector are instrumented and were monitored continuously. Inclinometers in the Southeast Sector were measured daily. TDR wells were read weekly. Water levels can be measured in both TDR wells and Inclinometers. These water levels as well as standalone piezometers were measured either daily or monthly (TDR wells). Berkeley Pit - Active Sectors Sector nomenclature for the Berkeley pit is detailed on Plate II (attached).

Figure 1. TDR Well locations.



Bird Watch Sector: The Bird Watch Sector monitor points did not exhibit any abnormal movement during the First Quarter of 2017. Slow displacement of the outer portion of the dump continues at a rate of less than 0.6 inches per month. The TDR cable in Well B06-1 did not demonstrate any progressive distress during this period. Concentrator Sector: Survey points were checked in this sector throughout the quarter with no significant movement being indicated. There was no significant movement indicated by the wire extensometers in the Concentrator Sector during the quarter. Minor movements appeared to be insignificant and not progressive. TDR cable readings did not demonstrate any progressive movement during the quarter. Southeast Sector: The Southeast Sector monitor points did not show any significant progressive movement during the First Quarter of 2017. Although the Southeast Sector extensometers are instrumented, they continue to be inspected up to three times per shift and readings recorded once a shift. If an automated data collector should go down, manual readings are taken three times per shift concurrent with the inspections. There was no significant movement indicated by the wire extensometers in the Southeast Sector during the quarter. Minor movements appeared to be insignificant and not progressive. Two extensometer repairs were made during the quarter due to deer traversing the area.

Dewatering pumps in the Southeast Sector of the Berkeley pit continued to operate throughout the First Quarter of 2017. The pumps installed in PZF15-1 and PZF 15-6 did not operate during the quarter. The pump installed in PZF15-2 was operable; however, the low water production from the well caused the pump to be shut down intermittently in February and March.



Table 2. Average flows for the PZF15 Dewatering Wells (First Quarter 2017).

Pittsmont Sector: Prisms on the Pittsmont dump were surveyed approximately once a week during the quarter. No slope movements were detected during the quarter. The TDR cables were read weekly during the quarter with no indicated distress. Hydrographs Water levels are tracked in all sectors. Hydrographs detailing the piezometric surface in each sector are provided in Figures 4 through 8. There were no unexpected fluctuations of note during the quarter in the Bird Watch, Concentrator, or Pittsmont Sectors.

Flow (gpm) Availability Flow (gpm) Availability Flow (gpm) Availability Flow (gpm) AvailabilityPZF15-1 0.0 0% 0.0 0% 0.0 0% 0.0 0%PZF15-2 24.4 100% 24.8 46% 29.2 66% 24.3 71%PZF15-3 114.0 100% 112.9 99% 108.9 97% 113.7 99%PZF15-4 15.7 100% 15.9 100% 16.7 99% 15.6 100%PZF15-5 18.8 100% 18.4 100% 22.0 99% 18.6 100%PZF15-6 0.0 0% 0.0 0% 0.0 0% 0.0 0%LP-15 39.5 100% 39.1 100% 36.9 100% 39.5 100%

March First Quarter 2017January FebruaryDewatering Wells



Figure 4. Hydrographs Bird Watch Sector.

Figure 5. Hydrographs Concentrator Sector.



Figure 6. Hydrographs Southeast Sector inclinometer wells.

Figure 7. Hydrographs Southeast Sector pumping wells



Figure 8. Hydrographs Pittsmont Sector.

M

A

I

N

S

U

B

S

T

A

T

I

O

N

COARSE ORE

STOCKPILE & TOWER

SECONDARY

CRUSHER

C

O

N

C

E

N

T

R

A

T

O

R

7 BELT

DRIVEHOUSE

P

A

R

K

I

N

G

L

O

T

F

I

N

E

O

R

E

B

I

N

S

D

U

S

T

C

O

L

L

E

C

T

O

R

S

Bird

Watch

Dump

O

I

L

H

O

U

S

E

R

U

B

B

E

R

W

A

R

E

H

O

U

S

E

P

A

R

K

I

N

G

L

O

T

W

A

R

E

H

O

U

S

E

PZF15-1

-64°

PZF12-8

PZF15-3

PZF15-4

PZF15-5

PZF12-6

Abandoned

PZF12-5

Note: Datum is mean sea level ACM (ift).

M

A

I

N

S

U

B

S

T

A

T

I

O

N

L

O

A

D

-

O

U

T

COARSE ORE

STOCKPILE & TOWER

SECONDARY

CRUSHER

1

-

A

B

E

L

T

&D

R

I

V

E

H

O

U

S

E

A

-

F

R

A

M

E

C

O

N

C

E

N

T

R

A

T

O

R

P

R

IM

A

R

Y

C

R

U

S

H

E

R

7 BELT

DRIVEHOUSE

P

A

R

K

I

N

G

L

O

T

F

I

N

E

O

R

E

B

I

N

S

D

U

S

T

C

O

L

L

E

C

T

O

R

S

D-1

Bird

Watch

Dump

NORTH

HAULTRUCK

PARKING LOT

O

I

L

H

O

U

S

E

R

U

B

B

E

R

W

A

R

E

H

O

U

S

E

P

A

R

K

I

N

G

L

O

T

W

A

R

E

H

O

U

S

E

PZF15-1

-64°

PZF12-8

PZF15-3

PZF15-4

PZF15-5

PZF12-6

Abandoned

PZF12-5

letter transmits attached settling defendants bmfou quarterly report … · 2017-11-13 · page 1...

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