Montana Resources Atlantic Richfield Company · Re: BUTTE MINE FLOODING SITE CD, CV 02-35 Bu-RFC,...

Montana Resources Atlantic Richfield Company

600 Shields Ave. 31 y Anaconda Road Butte, Montana USA 59701 CMX/IDOWIUICWTAI Butte, MT 59701 59701(406)496-3200 ENVIRONMENTAL Main (406) 782-9964 (406) 723-9542 fax PROTECTION AGENCY Fax (406) 782-9980 www.montanaresources.com $ | A BP affiliated company

NOV 21 201S November 15, 2016

MONTANA OFFICE

Certified Mail Certified Mail Mr. Henry Elsen, Esquire Mr. Jonathan Morgan, Esquire U.S. EPA Region VIII, Montana Office Legal Counsel Baucus Federal Building Mine Flooding CERCLA Site 10 West 15th Street, Suite 3200 Montana Department of Environmental Quality Helena, Montana 59626 P.O. Box 200901

Helena, Montana 59620-0901

Certified Mail Certified Mail Mr. Nikia Greene, Remedial Project Manager Mr. Daryl Reed, State Project Officer US EPA Region VIII, Montana Office Montana Department of Environmental Quality Federal Building State of Montana 10 West 15th Street, Suite 3200 Phoenix Building, P.O. Box 200901 Helena, Montana 59626 Helena, Montana 59620-0901

Re: BUTTE MINE FLOODING SITE CD, CV 02-35 Bu-RFC, 2016 Third Quarter Report

Dear Mr. Morgan, Mr. Elsen, Mr. Greene and Mr. Reed:

The Settling Defendants (Atlantic Richfield Company and the MR Group, as defined in the Consent Decree) continue to implement the remedial action requirements as specified in the Statement of Work to the Consent Decree. The attached report summarizes those activities conducted during the Third Quarter of 2016.

Please contact us if you would like to discuss this BMFOU Quarterly Report.

On behalf of the Settling Defendants,

Mark Thompson Tim Hilmo, P.E. Manager of Environmental Affairs Operations Project Manager Montana Resources LLP Remediation Management Services Company 600 Shields Avenue An affiliate of Atlantic Richfield Company Butte, MT 59701 317 Anaconda Road

Butte, MT 59701

'•

Lhallaue

Text Box

1551956 - R8 SDMS

CC: Rebecca Summerville, Esq. Datsopoulos, MacDonald, and Lind P.C. (email copy) Steve Walsh, MR (email copy) Cord Harris, AR (email copy) Irene Montero, AR (email copy) Jean Martin, AR (email copy) John Davis, Esq. Poore, Roth and Robinson P.C. (email copy) Bill Duffy Esq., Davis Graham and Stubbs, LLP (email copy) Terence E. Duaime, MBMG (email copy) Jim Jonas, Copper Environmental (email copy) Don Booth, Booth Consulting (email copy) Joe Vranka, EPA (email copy)

File [email protected]

Attachments

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

QUARTER 3, 2016

The Settling Defendants1 continue to implement the remedial action requirements specified in the Statement of Work to the Consent Decree. This report summarizes those activities conducted during the third quarter of 2016 as required under section X. Reporting Requirements, Paragraphs 3land 35 of the Consent Decree. The headings (a-g) in the following report correspond to the categories identified in paragraph 31. The sections captioned Issues Encountered and Other have been added at the request of the EPA.

a) Actions Taken Toward Achieving Compliance with the Consent Decree

To achieve compliance with the Consent Decree, 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 part of the Consent Decree. These seven components and the remedial action activities undertaken by the Settling Defendants (hereinafter referred to as "SDs") in the third 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. 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 instability in the eastern sector of the Berkeley Pit has created a safety issue for persons entering the Berkeley Pit including persons 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 have 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 being undertaken.

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.

BMFOU Quarterly Report Page 2 Quarter 3, 2016 November 15, 2016

During Q3 2016 no significant slope failures occurred within the Berkeley Pit.

The SDs are continuing to formulate the concepts to safely enable resumed water sampling, and potentially on-water waterfowl mitigation activities, while mitigating risk to personnel, as discussed above.

Normal waterfowl mitigation efforts continue according to plan; only on-water inspections have been suspended.

The SDs provided access to the MBMG personnel to conduct monitoring.

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.PTTWATCH.ORG. These are the primary vehicles for educating the public about BMFOU status and activities. A PITWatch magazine was published during Q3 2015. A PITWatch meeting is scheduled for October 2016.

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 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 Montana Resources, LLP ("MR"). Treated HsBWTP water has been integrated into MR's milling water circuit since the HsBWTP was commissioned in November 2003.

During the quarter, approximately 1,774,500 gallons of HsB flow was bypassed to the Berkeley Pit:

• Approximately 155,000 gallons on 7/13/16 to modify power supply to the WTP.

• Approximately 160,000 gallons on 7/17/16 resulting from flow limitations during clean out.

• Approximately 1,306,500 gallons on August 24, 2016 due to planned mill shutdown requiring the shutdown of HsBWTP;

• Approximately 153,000 gallons on September 21, 2016 due to a power outage.

http://www.PTTWATCH.ORG

BMFOU Quarterly Report page 3 Quarter 3, 2016 November 15, 2016

Stage 2 of the HsBWTP was bypassed and taken out of service for annual maintenance on May 19, 2016. Stage 2 was brought back on-line August 1, 2016, at which time Stage 1 was bypassed and taken out of service for annual maintenance. Stage lwas brought back online on September 1, 2016 and the WTP operated in dual stage mode for the remainder of the quarter.

As part of the 2016 annual maintenance, the influent equalization basin was dredged to remove accumulated sediments, the Stage 2 reactor walls were descaled and concrete inspections were conducted on all WTP vessels.

In 2015, the SDs in consultation with MBMG performed maintenance on the HsB Drainage weir directly upstream of the HsBWTP diversion structure. The maintenance increased the accuracy of the weir. A summary memorandum documenting the maintenance activities was completed and submitted to the agencies on August 11, 2016.

Punch list items from Swank Enterprises' work to implement piping maintenance to increase the WTP flow capacity were completed in Q1 2016. A summary memorandum documenting the piping maintenance activities completed was submitted to the agencies on August 11, 2016.

Significant maintenance activities completed during the quarter include:

• Rebuilt grit conveyor on north slaker; • Replaced pinch valve on north slurry tank return line; • Cleaned effluent flow meter; • Installed 2 new valves on south lime slurry tank discharge; • Replaced 2nd stage sludge pump; • Replaced 1st stage sludge pump; • Replaced the south slaker paddle shaft, end bearings and seals; • Influent pond dredged to remove accumulated sediments; • Replaced flow meter on 2nd stage blower line; • Replaced screen on south slaker PLC panel; • Cleaned scale from 2nd stage reactor walls; • Repaired coating on 2nd stage reactor walls.

Control of groundwater levels in the vicinity of the HsBWTP continued. Engineering controls operated during the third quarter and regulated the groundwater level in the


area of the HsBWTP. Please refer to Attachment 1 of this report for the Groundwater Level Reduction Summary Report.

4. HsB Water Treatment Plant Upgrade/Sludge Repository - The SDs have initiated the Horseshoe Bend Water Treatment Plant Remedial Action Adequacy Review to ensure that ongoing and future remedial activities will meet the requirements of the CD. The Draft Site Activity Schedule for the HsBWTP Remedial Action Adequacy Review ("RAAR") was submitted on June 30, 2014 and approved by the Agencies on September 11, 2014. The Scope of Work ("SoW") for the RAAR was subsequently prepared to evaluate four primary tasks with appropriate subtasks. 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 schedule and scope of work also respond to the issues raised by the Agencies in the February 20, 2014 letter to the SDs regarding the Agencies response to the BMFOU Five-Year Review Issues. The RAAR contractor will periodically update the detailed schedule as needed.

The primary tasks in the RAAR include:

Task 1. HsBWTP O&M Optimization: • Short term optimization; • Long term optimization; and, • 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; and, • Integrate water quality into predictive water balance.

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

Task 4. Technical Memorandum Preparation.

The SD's 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 Consent Decree, Section VI. PERFORMANCE OF THE WORK BY THE SETTLING DEFENDANTS, Paragraph 10, Selection of Supervising Contractors.


On September 2, 2016, the Draft Final Water Balance Work Plan was submitted to the agencies. It is anticipated that the agencies will provide comments on the work plan in October 2016.

The Explanation of Significant Differences, Appendix A to the CD allows for placement of sludge into the Berkeley Pit. During Q3, all of the sludge generated by the HsBWTP was placed into the Berkeley Pit (see Table in Section 7b). The evaluation of sludge disposal in the Berkeley Pit is also included as an activity on the RAAR schedule.

5. West Camp System - During the third quarter of 2016, approximately 21.2 million gallons of water were pumped from the West Camp pump station 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 5421.02' (NGVD29).

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 on-water activities. The SDs continued to perform waterfowl mitigation efforts under the variance from this requirement of the Waterfowl Mitigation Plan.

The SDs submitted the June, July and August, 2016 Berkeley Pit Migratory Waterfowl Mitigation Monthly Reports, which included the Observation and Hazing logs as attachments to the report letters. Please see these reports for a description of the detail of mitigation efforts.

7. Institutional Controls - Full SD compliance with this component of the RA SOW was completed by funding provided in 2002 by the SDs past and future cost cash out provisions of the Consent Decree. The Butte Alluvial and Bedrock Controlled Ground Water Area ("BABCGWA") was established by the MT DNRC in October 2009 with Butte-Silver Bow as the petitioner. Implementation and monitoring of the BABCGWA was assigned to the MBMG and funding from the SDs cash out amount that was provided in 2002. The outer perimeter of the area was determined and covers 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. September 2013) and consult Mr.


Terrence E. Duaime, Project Manager of the Montana Bureau of Mines and Geology 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 HsBWTP in Quarter 3 2016 and in total for the year to date:

Period Influent HsB Sludge Lime Average Average (MG) Plant Wasted Delivered Influent Flow Lime Usage

Water2 (MG) (tons) (MGD) (mg/L) (MG)

Quarter 1 427 469 17 3,745 4.7 2,117 Quarter 2 410 444 21 4,613 A5 2,705 Quarter 3 420 430 24 4,213 4.6 2,407 Quarter 4

YTI) 1,257 1,343 61 12,571 4.6 2,410

HsBWTP water is sampled at multiple locations including the HsBWTP influent and, Stage 1 Clarifier overflow (during 2 stage operation), and Plant Water (Mill influent formerly named plant effluent). These data will be utilized in the RAAR HsBWTP Optimization currently ongoing. The testing demonstrates that the current operation of the HsBWTP 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 HsBWTP, engineering controls associated with groundwater monitoring and dewatering to manage the groundwater elevation continued to operate. Please see Attachment 1 to this report.

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

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.


c) Identify all work plans and other deliverables required by this Consent Decree completed and submitted in the previous quarter

On September 2, 2016, the Draft Final Water Balance Work Plan was submitted to the agencies for comment.

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 fourth quarter 2016 anticipated activity summary is as follows:

1. The Monitoring Plan will continue to be implemented during the next quarter, with the exception of sampling the Berkeley Pit, and the SDs will continue to provide access, cooperation and any assistance to the MBMG requested in performing this task. SDs will continue to pursue safe methods of sampling the Berkeley Pit by progressing the remote sampling platform.

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 HsBWTP 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 HsBWTP treated water being integrated into the mining and milling operations. It is also anticipated that the inlet sump vault will be cleaned.

4. Operation of the dewatering system around the HsBWTP will continue.

5. The HsBWTP Short-term Optimization draft Technical Memo will be prepared for submittal in Q4.


6. It is anticipated that comments for the agencies regarding the RAAR Work Plan for the Water Balance will be received and a final Water Balance Work Plan will be submitted to the Agencies in Q4.

7. Sludge from the HsBWTP 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 CWL.

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.

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 IX. Access and Institutional Controls section of the CD.

11. The RAAR Site Activity Schedule will be followed and modified, as needed, with modifications approved by the Agencies. The HsBWTP optimization, BMFOU site-wide water balance update and alternatives study will continue according to the RAAR Schedule.

12. The Q4 2016 deliverables include: i. Final BMFOU Site-Wide Water Balance Work Plan will be submitted;

and ii. Draft HsBWTP Short-term Optimization Draft Technical Memo.

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 and 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. (Please see the discussion in section lof this report regarding the agreement entered into between the SDs and Montana Tech.)

e) Include any modifications to the RA or RD Work Plans or other work plans or schedules that Settling Defendants have proposed to EPA or that have been approved by the EPA.

There are no current, requested modifications to the RA or RD Work Plans or schedules proposed to the agencies.

I) 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 in Actions Taken Toward Achieving Compliance. 2. Public Education and Involvement for details to the answers to this reporting requirement.

g) Issues Encountered

No new issues were encountered during the quarter.

h) 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 third 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 (Consent Decree, IX. ACCESS AND INSTITUTIONAL CONTROLS, part 26b., p. 39).

Attachment 2 is a report for Q3 titled "Berkeley Pit Slope Stability Quarterly Summary" 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.

MR implemented a stability enhancing effort along the Concentrator section of the Berkeley Pit to secure MR's haul road. The work includes the installation of soil nails (also referred to as micro-piles) and is anticipated to be completed in Q4 2016.


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

BMFOU Quarterly Report page n Quarter 3, 2016 November 15, 2016

BMFOU QUARTERLY REPORT

Q3 2016

ATTACHMENT 1:

Horseshoe Bend Water Treatment Plant Groundwater Level Reduction Project

©Montana Resources, LLP Montana Resources 600 ShieldsAve-

Butte, Montana USA 59701 (406) 496-3200 (406) 723-9542 fax www.montanaresources.com

MEMORANDUM

TO: Mark Thompson

FROHVl: Amanda Griffith

DATE: November 7, 2016

SUBJECT: HsBWTP GWL Reduction-2016 3rd Quarter Summary

Overview

The Horseshoe Bend groundwater dewatering system was operated continuously through the third quarter except for five 2-8 hour long intervals when the power was out. The dates of the outages were 7/13/2016 for approximately 5 hours, 8/22/2016 for approximately 2 hours, 8/25/2016 for approximately 2 hours, 8/29/2016 for approximately 8 hours and 9/21/2016 for approximately 5 hours. The power was shut down for plant maintenance and to reroute outgoing pipes. Individual wells were also shut down for less than ten minutes a piece 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 HI 4-4, HI 4-5, and HI4-6 are off indefinitely after maintenance issues impacted production, water levels and pumping rates were monitored to determine their effect on the dewatering of the area. No new wells were installed during the third quarter. The water levels in the pumping wells remained fairly steady over the quarter except in the three deep wells, H14-4, H14-5, and H14-6. In H14-4 and HI4 -6 the pumps seized after decreased flow and increased amperage drawn by the pump. The pump in HI4-5 was shut down because the well was not producing adequate water to be pumped. The water level in the two monitor wells increased slightly over the quarter, but it is unclear whether this was a result of termination of pumping in the deep wells or a result of several pump shutdowns in late August for maintenance and outgoing pipe rerouting, or changes in ground water flow quantities. The other wells will continue to be pumped and monitored to determine if pumping the deeper wells is necessary for bringing the water level below the tanks.

The water level in monitor well HI4-3 fluctuated from week to week, but increased bv 0.24 feet over the quarter. The water level in monitor well HI5-9 increased 0.89 feet over the quarter. Changes in water level over the third quarter can be seen in Table 2. As a result of increased water levels, a round of pump and well maintenance was completed, as discussed below. After maintenance activities and during Q4 2016, water levels will be monitored to determine if the maintenance activities completed will reduce water levels.

A Washington Company

HsBWTP GWL Reduction-2016 3rd Quarter Summary Page 2 of 6

Maintenance was performed on four pumping wells during the third quarter of 2016. The pumps were removed from HI5-7, HI5-8, HI5-10, and HI5-11 to surge and bail the wells to increase flow. The pump ends were replaced with clean ends. The pump motor was replaced in HI 5-8. The maintenance was performed from 9/12/2016-9/16/2016.

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.


ffi Table 1. Pumping rates for HsBWTP dewatering wells. 3

HsBWTP Flow Rates ^ r— O 7/7/2016 7/14/2016 7/21/2016 7/28/2016 8/4/2016 8/11/2016 8/18/2016 8/26/2016 9/1/2016 9/8/2016 9/15/2016 9/22/2016 9/29/2016 ^

Pump Average Average Average Average Average Average Average Average Average Average Average Average Average ^ H14-1 40.2 45.9 43.2 42.1 42.5 43.8 43.8 46.3 43.6 51.4 42.3 53.4 43.7 J H14-2 6.5 6.0 6.1 6.5 6.4 6.7 6.3 6.7 6.4 0.0 12.9 15.1 12.9 + Q< H14-4 2.4 2.4 2.3 0.4 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 C H14-5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5.6 4.1 0.0 0.0 0.0 0.0 §* H14-6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ® H15-7 1.9 1.7 1.5 1.4 1.3 1.3 1.6 2.1 2.5 2.2 0.0** 0.0** 3.6 + g H15-8 8.5 9.7 8.6 8.7 8.1 8.6 8.7 9.4 9.9 9.9 10.1 0.0 14.7 + H15-10 3.6 3.1 2.5 2.4 2.5 2.5 2.6 0.0 0.0 4.0 4.9 5.3 5.4 + ^ H15-11 0.0** 0.0** 0.0** 0.0** 0.0** 0.0** 0.0** 0.0** 0.0** 0.0** 0.0** 0.0** 8.6 + 2.

|H15-12 87 87 83 83 87 83 8A 83 103 93 93 137 11.1 + Q C £5 * indicates an overall decrease in flow

+ indicates an overall increase in flow o ** well inaccessible for flow testing ^

C B B

13

•"O p CTQ O

I O f ^ <§ § £ I

^ V X":" ^ HsBWTP ^ Z ^ \j/ \ V\ \ \ Nv GWL Reduction g^ | / \ \ \ \ \ X^ "" ~~~^x Dewatering and f / \ \ \ \ \ \ ^ * Monitor Wells 1 | / ) \ \ \ \ T 1 4 " 3 \ E x i s t i n g w e l l s } 1 1/ i \ K \ \ \ 1 ^ 1 1

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

aj 3rd Quarter HsBWTP Water Levels &

5,580 , < H —B— H14-1 -g

—»— H14-2 O — — H14-3 p

A *—A i—A. -A A — - .4Aii A A a • i"~!' Jj~ " ~ ft. ^ ~ L —H 1 4 - 4 J S 3 / \ —:*-H14-5 Q.

f 11 y y n 11 -iff »1 i 3— *—mr <6 ~ % i —HM-S | ~ 5,540 1 1 < g | t j > | ||| g-g « - r- » » #^^***# # f H15-7 3 | I -14 g-| B " *£ * —•—H15-8 g

5,520 / H15-11 O 8 £=*-* *-/ fi D \ —•— H15-12 » VI V «-A z • *-« *-« »-* a** *-# «—« « rt> o -t < &P S 5,500 — g J-J * *-* *-* W-* -*-* *** *-* „ * 3

° A S (M \ fr 3 \ I 1!

5,480 - - V j _ -

5,460 - -^5 Ifl lO U3 O S S 3 T5 d d ™ ° P> c d d d o

2 5 DATE O 5 _ __ g. ? Figure 2. HsBWTP dewatering and monitor well levels for 3rd quarter of 2016. £

i

' — —— —

HsBWTP GWL Reduction-2016 3rd Quarter Summary Page 6 of 6

I able 2. Pumping and static water levels ol the HsBWTP dewatering and monitor wells 6/30/2016 through 9/29/2016.

9/29/2016 9/29/2016

Water Water Screened

elevation elevation Change from interval

Well (USGSft) (ACM ft) 6/30/2016 (ft) (ACM ft)

H14-1* 5537.07 5484.44 -1.04 5562-5582 H14-2* 5537.11 5484.48 -0.30 5561-5581

H14-3 5536.76 5484.13 0.24 5555-5575

H14-4** 5536.76 5484.13 17.45 5538-5558 H14-5** 5536.74 5484.11 2.49 5515-5535 H14-6** 5536.77 5484.14 15.48 5535-5555 H15-7* 5536.78 5484.15 -0.19 5593-5623 H15-8* 5536.73 5484.10 0.06 5592-5602 H15-9 5536.75 5484.12 0.89 5597-5507

H15-10* 5536.73 5484.10 0.03 5572-5592 H15-11* 5536.82 5484.19 -2.62 5576-5596 H15-12* 5536.72 5484.09 0.00 5582-5612

* Pumping well

** No longer pumping


BMFOU Quarterly Report page ^2 Quarter 3, 2016 November 15, 2016

BMFOU QUARTERLY REPORT

Q3 2016

ATTACHMENT 2:

Berkeley Pit Slope Stability Quarterly Summaries

©Montana Resources, LLP Montana Resources l°°stIifld?Ave.^

Butte, Montana USA 59701 (406) 496-3200 (406) 723-9542 fax www.montanaresources.com

MEMORANDUM

TO: Stephen Walsh

FROM: S. Huckeby

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

DATE: October 24, 2016

SUBJECT: Berkeley Pit Slope Stability Third Quarter Summary 2016

Summary

Monitoring of the Berkeley Pit highwall slope stability continued throughout the Third Quarter of 2016. The monitoring network is illustrated in Plate I and summarized in Table 1.

Table 1. Berkeley monitoring network Third Quarter 2016.

IS) </> c QJ £ no — Oc QJ -E .E >

BERKELEY PIT o. J E | .o J ^ i HIGHWALL STABILITY 2 i | ° £ | I £

r I I e S I *=• UJ

Bird Watch Sector 4 — — 1 1

Concentrator Sector 3 3 — 3 5

Southeast Sector 5 3 4 — 5 21

Pittsmont Sector 3 — — 4 3

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).


Berkefley Slope Stability Quarterly Summary July - Sept 2016 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.

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).

j i-:-" ., PZF-J-1A : I '' P2F14"1B

. <{. : ' $ ~ ^ ^ f 3 I R D • T5rfSN'QN7

WATCH mffl/j PZF13-1 SECTOR K CONCENTRATOR

SE(Sjr.OR '/TSr .,/., • f5 B06-01 " • \ .'

T PZF98-2 \ \ • PZF&a-i X

/ PZF98-3 •

,X - L ' ' f

T' T' J ^

Figure 1. TDR Well locations.

Bird Watch Sector: The Bird Watch Sector monitor points did not exhibit any abnormal movement during the Third Quarter of 2016.


Berkeiey Slope Stability Quarterly Summary July - Sept 2016 Page 3 of 7

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.

One extensometer repair was made during the quarter due to deer traversing the area.

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 Third Quarter of 2016. Four monitor points were abandoned due to heavy equipment damage during the Third Quarter.

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 Third Quarter of 2016. The pump installed in PZF15-1, did not operate during the quater. The pump installed in PZF15-6 was shut down on August 11th due to the soil nail installation project.


Berkeley Slope Stability Quarterly Summary July - Sept 2016 Page 4 of 7

Table 2. Average flows for the PZF15 Dewatering Wells (Third Quarter 2016).

Dewatering July August September Third Quarter 2016 Wells Flow(gpm) Availability Flow(gpm) Availability" Flow(qpm) I Availability Flow(gpm) Availability

PZF15-1 0.0 0% 0.0 0% 0.0 0% 0.0 0% PZF15-2 23.8 99% 25.6 100% 12.0 100% 21.0 99% PZF15-3 108.2 90% 112.4 100% 111.8 100% 110.6 97% PZF15-4 14.2 100% 14.6 100% 14.8 100% 14.6 100% PZF15-5 17.2 100% 17.3 100% 5.6 100% 12.5 100% PZF15-6 0.3 100% 0.4 33% 0.0 0% 0.3 32% LP-15 40.9 100% 40.6 100% 40,4 100% 40.6 100%

Pittsmont Sector: Prisms on the Pittsmont dump were surveyed approximately five days per 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.

3rd Quarter Bird Watch Sector TDR Wells 5350

5345 t - - - - - — -

t 3340 j

•j; . _ - - - ~ -* 5335 j L- - _

8—•— BERKCLfr PIT 5330 - — — w ^ — 3S4-01 5 5325

O 5320 U -

5313 — j j

5310 I ! _! [_ ! 2 ^ 2 2 2 2 2 a 2 2 ' ^ i S 2 , a 3 2 X I 8 P J R tw

, I

Figure 4. Hydrographs Bird Watch Sector.



3rd Quarter Concentrator Sector TDR Wells » —, ——T

| 5440 | [— i 1 ^

j s - SHOO -1 ' — ——I 1

j 4

5 * I I —•- Bcnaic prr g 5380 1

3, * j '"•* P2f»»0i

f 5360 - . _ . PZWMI

a i ! I I | ^ PZF98-OJS §

SS40 T 1 j m 9»o»o

H~- • 1 —— 4- — > —•— PZPOfrOt

5320 —| i

5300 -i f- —4 1 I |

i I I 1 1 ! ! ! ! ! I I I I Data

Figure 5. Hydrographs Concentrator Sector.

3rd Quarter 2016 Berkeley SE Sector Inclinometer Wells 5420

5380

1 1 5,60 mill II—I "*!• y im—twirn ««——•••— •"a"" ! g PZF12-5

! J -*-PZF12-> g S340 —PZF12-6 | " — ' " " ~~ PZF12.8

BJ Berk H20 o 2 5320 • •**——- • • j- J

|i M00 j —' ! , ! i I i j p i ! I I 5280 — ——

*- i t i I i ! I I i ! I I I Date "

Figure 6. Flydrographs Southeast Sector inclinometer wells.



3rd Quarter 2016 Berkeley SE Sector Pumping Wells 5600 —

IMO i .— , |— i——— -i -1 , ! i I I L——

, „ ^— ! I1- •1 1 | t"' 'V | [••"•y'M'.'MyniT

3 MWO S 5500 •—-PZF15.1 5 nr i6-2 I I I """" 1 I PZF 1W | lwo 4 I I ! 0 PZF IM

j >100 1 _ 1. I 1 i

5000 i

3 5 3 5 I I | ! I 2 2 2 J J Date

Figure 7. Flydrographs Southeast Sector pumping wells

3rd Quarter 2016 Berkeley Pittsmont Sector PZF Wells 5500 ——

5050 • _ !_ !_ I j | I j |

1 ~ - | ' — j [—1 — | I 1 ' | I —*ZFIM | — — — ••••;• Ti -•••PZF10.1A 1

| i j J -»-PZF14-1A J Beck HJO 9100 1 1 I _ II S

X

5250

5200 ____ -

i i \ I i j * i i * i | * t 2 2 % * ' a ' ' £ ! 3 &

Opto

Figure 8. Flydrographs Pittsmont Sector.


r


Other Activities:

Initiation of the soil nail/micro pile haul road stabilization project commenced in mid-August 2016. The soil nails were installed along the Rim Haul Road to stabilize the Berkeley Pit highwall. The project is scheduled to be completed in the beginning of November.


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