Atlantic Richfield Company• Field trial on the Berkeley Pit on May 9, 2017 where a vertical profile was completed to a depth of 625 feet and a sample was collected at a depth of

600 Shields Ave. 317 Anaconda Road Butte, Montana USA 59701 Butte, MT 59701 59701(406) 496-3200 Main (406) 782-9964 (406) 723-9542 fax Fax (406) 782-9980 www.montanaresources.com A BP affiliated company

Atlantic Richfield Company

August 15, 2017 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, 2017 Second 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 Second Quarter of 2017.

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

http://www.montanaresources.com/

Lhallaue

Text Box

1818427 - 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) Rich Keeland, Pioneer Technical (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 Second Quarter, 2017

BMFOU Second Quarter Report Page 1 of 10

SETTLING DEFENDANTS BUTTE MINE FLOODING OPERABLE UNIT (BMFOU) QUARTERLY REPORT

CONSENT DECREE FOR THE BUTTE MINE FLOODING SITE CD, CV 02-35 Bu-RFC

REMEDIAL ACTION – IMPLEMENTATION OF THE REMEDY SECOND QUARTER 2017

The Settling Defendants1 continue to implement the Remedial Action (RA) 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 second 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 RA 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 second 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. Installing 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 the second quarter, MBMG installed pressure transducers with direct read cables in the Anselmo, Kelley, Lexington, Pilot Butte and Steward Mine shafts. The MBMG is also developing a plan to install pressure transducers with a direct read cable to the Marget Ann Mine shaft in the third quarter of 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 instability in

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.


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 RA. 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 during the second quarter included the following: • Field trial on the Berkeley Pit on April 5, 2015 where a vertical profile was completed

to a depth of 205 feet before the purge line wrapped around one of the boat motor propellers and the trial was aborted.

• Field trial on the Berkeley Pit on May 9, 2017 where a vertical profile was completed to a depth of 625 feet and a sample was collected at a depth of 3 feet.

• Field trial on Silver Lake on June 15, 2017 where the sampling system was tested. During the second quarter of 2017, no significant slope failures occurred within the Berkeley Pit. Montana Resources LLP (MR) provided access to 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.PITWATCH.ORG. These are the primary vehicles for educating the public about BMFOU status and activities. A PITWatch meeting was held on May 1, 2017, in which the SDs participated. The PITWatch committee, with support from the SDs, is developing several articles for publishing. In addition, as part of a sponsored research agreement between the SDs and Montana Tech, various local waterfowl experts from around Butte and western Montana agreed to participate in the formation of the Berkeley Pit Migratory Waterfowl Mitigation Advisory Board (Waterfowl Advisory Board) to provide advice on avian-related Berkeley Pit topics, including, but not limited to, ways to deter birds from landing/remaining in the Berkeley Pit. The Waterfowl Advisory Board met on April 20 and June 7, 2017. The SDs are currently working with the Waterfowl Advisory Group to evaluate additional waterfowl mitigation measures and update the Waterfowl Mitigation Plan. On May 30 and 31, 2017, the SDs in conjunction with the product vendors, conducted a demonstration of the Vortex Ring Avian Deterrent (VRAD), a novel high-powered, sonic bird deterrent technology at the Berkeley Pit. The demonstration included the Agencies, members of the Advisory Board and coverage of the event by various local media.

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

http://www.pitwatch.org/


the Record of Decision (ROD) was issued in 1994 and treated HSB water was integrated 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 this quarter, a total volume of approximately 448,000,000 gallons was treated. During this quarter 2,407,120 gallons of HSB flow (approximately 0.5% of the total treated volume for this quarter) was bypassed to the Berkeley Pit for the following reasons: • 1,544,000 gallons bypassed from 4/12/17 to 4/13/17 due to a planned mill down day. • 115,000 gallons bypassed on 6/5/17 through 6/6/17. • 778,000 gallons bypassed from 6/12/17 to 6/13/17 due to heavy rains. • 15,120 gallons bypassed on 6/21/17 due to a planned mill down day. Significant maintenance activities completed during the quarter included:

• Access door was installed in the north slurry tank. • Valves on the north slurry pumps were moved to eliminate plugging due to dead legs

of pipe where material built up. • North slurry tank was descaled. • Lime addition valve AV-2 was changed. • Stainless steel check valves were installed on influent pumps Nos. 114 and 115. • New Silver Lake water supply lines were installed in the plant. • Influent pump No. 115 was replaced (broken shaft). • Effluent Pump No. 113 was replaced (reduced flow). • New shaft was installed in the second stage blower line discharge valve (shaft broke). • New sludge sample lines were installed on first and second stage alkalization tanks.

Stage one was bypassed and taken out of service on May 1, 2017, for annual maintenance. As part of the annual maintenance, Veolia was contracted to remove the scale build up in the stage one reactor. The concrete was also inspected in both the reactor and clarifier. Stage one was brought back online June 26, 2017, and stage two was bypassed and taken out of service for annual maintenance which continued into the third quarter. Control of groundwater levels in the vicinity of the HSB WTP continued. Engineering controls operated during the second quarter and regulated the groundwater level in the area of the HSB WTP. Second quarter 2017 reporting for these activities is included in the Horseshoe Bend Water Treatment Plant Groundwater Level Reduction Project Quarterly Report provided as Attachment 1 of 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 2016 fourth quarter 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 SOW 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. On June 21, 2017, the SDs notified and requested approval from the Agencies to change the RAAR “Supervising Contractor” from Golder and Associates to Arcadis and provided a statement of qualifications for Arcadis to the Agencies. On June 27, 2017, the Agencies approved Arcadis 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 third quarter of 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 Agencies’ comments and the BMFOU RAAR Final Water Balance Work Plan will be provided in the third quarter of 2017. The Explanation of Significant Differences, Appendix A to the CD, allows sludge to be placed into the Berkeley Pit. During the second quarter, all the sludge generated by the HSB WTP was placed into the Berkeley Pit (see the table in Section b). The evaluation of sludge disposal alternatives is also included as an activity on the BMFOU RAAR schedule.

5. West Camp System – During the second quarter of 2017, approximately 18.7 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 5,421.96 feet (National Geodetic Vertical Datum [NGVD] 29) below the West Camp Critical Water Level of 5,435 feet (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 above. The SDs continued to perform waterfowl mitigation efforts under the variance from this requirement of the Berkeley Pit Waterfowl Mitigation Plan.

An unprecedented 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 the second quarter of 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. During the second quarter, the SDs worked to implement and evaluate the interim measures described in the document.

• The SDs continue to investigate the Nov. 28, 2016 event in an effort to better understand the circumstances for improving future prediction and prevention measures. To this end, the SDs continue to engage with the Waterfowl Advisory Board, and have retained additional waterfowl experts to support this effort. The SDs will submit a revised Interim Measures Plan for Fall 2017 migration period (August 15 through December 31) that include these experts’ input and recommendations in the next quarterly report. Further, the SDs anticipate completing technical memoranda and/or reports being developed by the Waterfowl Advisory Board and additional waterfowl experts during the next reporting period. These reports/memoranda will be submitted to the Agencies once completed and/or as attachments to the third quarter report.


On June 26, 2017, the Agencies requested additional information from the SD’s regarding the November and December 2016 Berkeley Pit Migratory Waterfowl Mitigation Monthly Report (SDs, 2016). The SD’s will submit a response to the Agencies questions in the third quarter.

During the second quarter, the SDs submitted monthly waterfowl mitigation reports, which included a detailed description of the mitigation efforts and the observation and hazing logs for the months. The following monthly waterfowl mitigation reports were submitted to the Agencies in the second quarter: 1. January, 2017 Berkeley Pit Migratory Waterfowl Mitigation Monthly Report (SDs,

2017) on April 10, 2017. 2. February 2017 Berkeley Pit Migratory Waterfowl Mitigation Monthly Report (SDs,

2017) on April 14, 2017. 3. March 2017 Berkeley Pit Migratory Waterfowl Mitigation Monthly Report (SDs,

2017) on April 28, 2017.

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 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. Implementing and monitoring the BABCGWA was assigned to the MBMG with funding being provided by the SDs cash out 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, 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 Table 1 summarizes the performance of the HSB WTP in the second quarter of 2017, and in total for the year.


Table 1 – HSB WTP Second Quarter Performance Table

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 2 448 432 29 4,450 4.9 2,379 Quarter 3 Quarter 4

Total 853 842 46 8,351 4.8 2,343 MG: millions of gallons. MGD: millions of gallons per day. mg/L: milligrams per Liter. 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 to the Agencies in the second quarter of 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 First Quarter 2017 (SDs, 2017) on May 15, 2017.

2. MBMG BMF Monthly Report BMFOU CD 02-35-BU-SEH Remedial Action-Monitoring Program Contract No. 415008-TO-2 April 2017 (MBMG, 2017) was submitted by MBMG on behalf of the SDs on May 15, 2017.

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.


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 third 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 cooperate in providing access and offer assistance to the MBMG 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 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 plans to install a pressure transducer with a direct read cable at the Marget Ann Mine shaft in the third quarter of 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 to be submitted in the third quarter of 2017. 6. It is anticipated that SD response to Agency comments regarding the BMFOU RAAR

Draft Final Water Balance Work Plan (SDs, 2016) and the BMFOU RAAR Final Water Balance Work Plan will be submitted to the Agencies in the third quarter 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 of 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 and additional waterfowl experts in this effort. Planned third quarter submittals associated with this investigation include a revised and supplemented version of the November/December 2016 monthly report and various technical memoranda/reports. In addition, the SDs continue to implement and evaluate additional activities 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, including submittal of an additional interim measures plan for the fall migration period in the third quarter.

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

provided to the Agencies, 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.

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 determining near term necessity of Pit water sampling, additional slope stability monitoring, risk assessment study, or adopting an alternative sampling and 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 Mine 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 of this reporting requirement.


h) Issues encountered

Safety concerns have led to the temporary suspension of water-level monitoring at the Granite Mountain Mine shaft 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.

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 from the second quarter titled Berkeley Pit Slope Stability second 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 Second Quarter Report

BMFOU QUARTERLY REPORT

SECOND QUARTER 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: July 28, 2017

SUBJECT: HsBWTP GWL Reduction-2017 2nd Quarter Summary

Overview

The Horseshoe Bend groundwater dewatering system was operated almost continuously through the second quarter of 2017. Three shutdowns occurred that affected all the pumping wells in the area. On 4/12/2017 all the wells were shut down for four hours for maintenance on the substation, on 4/19/2017 all the wells were shut down for 15 minutes for reasons unknown, and on 6/21/2017 all the wells were shut down for approximately 13 hours when power was shut off at the plant during yearly maintenance. Individual wells were also shut down for less than ten minutes apiece to reconnect outgoing pipes following weekly manual flow measurements and there were no major shutdowns. 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 are off indefinitely after maintenance issues impacted production. 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, with the exception of H15-12. The water level has steadily increased over the quarter while the flow rate has decreased.

The water level in monitor well H14-3 decreased by 0.02 feet over the quarter. The water level in monitor well H15-9 decreased 0.59 feet over the quarter. The water level in monitor well H16-13 decreased 0.54 feet over the quarter. The water in monitor well H16-14 decreased 0.04 feet. Changes in water level over the second quarter can be seen in Table 2.

No new monitor wells were installed during the second quarter. No maintenance was performed on existing wells. Because the water levels in the monitor wells all decreased during the 2nd quarter despite the pump in H15-12 becoming less effective, the pump will only be replaced if the water levels in the monitor wells begins to increase. 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 2nd Quarter Sum

mary

Page 2 of 5

A Washington Com

pany

All Elevations ACM Ground Level 5632.25 Ground Level 5631.02 Ground Level 5614.91 Ground Level 5618.0 Ground Level 5617.1 Ground Level 5631 Ground Level 5631.5

Datewater level below MP

water elevation

water level below MP

water elevation


water elevation


water elevation


water elevation


water elevation


water elevation

4/7/2017 45.71 5588.89 43.81 5589.66 39.99 5576.87 31.31 5588.80 66.69 5552.41 69.96 5563.22 31.53 5600.244/14/2017 44.89 5589.71 43.84 5589.63 40.19 5576.67 31.32 5588.79 66.88 5552.22 70.14 5563.04 31.75 5600.024/19/2017 45.14 5589.46 43.79 5589.68 40.31 5576.55 31.44 5588.67 67.12 5551.98 70.48 5562.70 31.71 5600.064/28/2017 45.41 5589.19 43.82 5589.65 40.26 5576.60 31.36 5588.75 67.04 5552.06 70.36 5562.82 31.61 5600.16

5/5/2017 43.29 5591.31 43.76 5589.71 39.98 5576.88 31.19 5588.92 66.92 5552.18 70.31 5562.87 31.88 5599.895/18/2017 44.74 5589.86 43.78 5589.69 40.21 5576.65 31.13 5588.98 67.03 5552.07 70.29 5562.89 31.69 5600.08

6/2/2017 44.81 5589.79 43.74 5589.73 40.05 5576.81 31 5589.11 66.87 5552.23 70.03 5563.15 31.67 5600.106/9/2017 44.81 5589.79 43.72 5589.75 39.83 5577.03 30.84 5589.27 66.53 5552.57 69.71 5563.47 31.6 5600.17

6/16/2017 44.95 5589.65 43.74 5589.73 39.98 5576.88 31.26 5588.85 66.72 5552.38 69.89 5563.29 31.56 5600.216/23/2017 45.67 5588.93 43.69 5589.78 40.02 5576.84 30.97 5589.14 66.82 5552.28 69.92 5563.26 24.92 5606.85

7/7/2017 44.82 5589.78 43.82 5589.65 40.18 5576.68 31.64 5588.47 67 5552.10 70.32 5562.86 31.52 5600.25

H15-7H14-6H14-1 H14-2 H14-3 H14-4 H14-5

All Elevations ACM Ground Level 5629.47 Ground Level 5631.64 Ground Level 5620.41 Ground Level 5622.84 Ground Level 5631.6 Ground Level 5628.85 Ground Level 5622.16

Datewater level below MP

water elevation


water elevation


water elevation


water elevation


water elevation


water elevation


water elevation

4/7/2017 32.75 5599.01 22.81 5611.62 40.24 5582.76 37.23 5588.62 41.21 5592.13 19.87 5611.57 23.99 5577.864/14/2017 32.91 5598.85 22.54 5611.89 40.44 5582.56 37.37 5588.48 41.26 5592.08 19.68 5611.76 23.91 5577.944/19/2017 32.93 5598.83 22.55 5611.88 40.02 5582.98 37.26 5588.59 41.25 5592.09 19.87 5611.57 24.17 5577.684/28/2017 32.82 5598.94 22.49 5611.94 40.04 5582.96 37.36 5588.49 41.21 5592.13 19.86 5611.58 23.9 5577.95

5/5/2017 32.79 5598.97 22.49 5611.94 39.24 5583.76 37.24 5588.61 40.97 5592.37 19.82 5611.62 23.84 5578.015/18/2017 32.79 5598.97 22.61 5611.82 40 5583.00 37.13 5588.72 27.94 5605.40 19.93 5611.51 23.86 5577.99

6/2/2017 32.93 5598.83 22.79 5611.64 40.06 5582.94 37.35 5588.50 26.41 5606.93 20.09 5611.35 23.61 5578.246/9/2017 32.88 5598.88 22.88 5611.55 39.99 5583.01 37.14 5588.71 26.31 5607.03 20.13 5611.31 23.73 5578.12

6/16/2017 32.81 5598.95 23.02 5611.41 40.09 5582.91 37.13 5588.72 26.48 5606.86 20.31 5611.13 23.92 5577.936/23/2017 32.97 5598.79 22.71 5611.72 40.32 5582.68 37.69 5588.16 24.81 5608.53 19.98 5611.46 24.07 5577.78

7/7/2017 32.82 5598.94 23.5 5610.93 40.32 5582.68 37.85 5588.00 26.78 5606.56 20.6 5610.84 24.34 5577.51

H15-10H15-9H15-8 H16-1 H16-2H15-12H15-11

Table 1. Pumping rates for HsBWTP dewatering wells for the 2nd quarter of 2017.

HsB

WT

P GW

L R


mary

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A Washington Com

pany

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

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5,490

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

HsBWTP GWL Reduction-2017 2nd Quarter Summary Page 5 of 5


Well

7/7/2017 Water

elevation (USGS ft)

7/7/2017 Water

elevation (ACM ft)

Change from 3/31/2017 (ft)

Screened interval (ACM ft)

H14-1* 5537.15 5589.78 0.92 5562-5582H14-2* 5537.02 5589.65 -0.01 5561-5581H14-3 5524.05 5576.68 -0.02 5555-5575

H14-4** 5535.84 5588.47 -0.13 5538-5558H14-5** 5499.47 5552.10 -0.09 5515-5535H14-6** 5510.23 5562.86 -0.12 5535-5555H15-7* 5547.62 5600.25 0.04 5593-5623H15-8* 5546.31 5598.94 -0.01 5592-5602H15-9 5558.30 5610.93 -0.52 5597-5507

H15-10* 5530.05 5582.68 -0.17 5572-5592H15-11* 5535.37 5588.00 -0.59 5576-5596H15-12* 5553.93 5606.56 14.41 5582-5612H16-13 5558.21 5610.84 -0.54 5579-5599H16-14 5524.88 5577.51 -0.04 5579-2289

* Pumping well** No longer pumping

Table 2. Pumping and static water levels of the HsBWTP dewatering and monitor wells 3/30/2017 through 7/7/2017.

BMFOU Second Quarter Report

BMFOU QUARTERLY REPORT

SECOND QUARTER 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: July 24, 2017

SUBJECT: Berkeley Pit Slope Stability Second Quarter Summary 2017

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

Table 1. Berkeley monitoring network (Second Quarter 2017).

Monitoring The monitoring network described in Table 1 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

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vels

4 — — 1 — 13 3 — 3 — 58 3 3 — 6 113 — — 4 — 3

BERKELEY PIT HIGHWALL STABILITY

Bird Watch Sector

Concentrator Sector

Southeast Sector

Pittsmont Sector

Berkeley Slope Stability Quarterly Summary April - June 2017 Page 2 of 7


Three monitoring points in the Bird Watch Sector were checked weekly and one monitoring point was checked daily. Monitoring points in the Southeast Sector and Concentrator Sector were checked 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. Time domain reflectometer (TDR) cables in the 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). On June 15, 2017, MSHA confirmed approval to adjust the monitoring frequency to the following schedule:

1. Survey all monitoring points in all sectors weekly, 2. Check and read extensometers in all sectors weekly, 3. Read TDR wells in every sector weekly, 4. Visually inspect the Southeast and Concentrator Sectors weekly, 5. Measure all water levels weekly, and 6. Read inclinometers bi-monthly.



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 monitoring points did not exhibit any abnormal movement during the Second 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: Monitoring 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 monitoring points did not show any significant progressive movement during the Second Quarter of 2017. 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. Three additional monitoring points were installed in May to replace the monitoring points removed from the Soil Nail Project.

Dewatering pumps in the Southeast Sector of the Berkeley Pit continued to operate throughout the Second Quarter of 2017. The pump installed in PZF15-1 did not operate during the quarter. The pumps installed in PZF15-2 and PZF15-6 were operable; however, the low water production from these wells caused the pump to be shut down intermittently during the quarter.

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

Pittsmont Sector: Prisms on the Pittsmont dump were surveyed 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.

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 70.5 10% 0.0 0% 23.2 12% 70.5 11%PZF15-3 110.8 99% 111.2 100% 107.6 100% 111.0 100%PZF15-4 14.0 99% 13.9 100% 14.0 100% 13.9 100%PZF15-5 22.2 99% 21.1 100% 19.9 100% 22.2 100%PZF15-6 0.0 0% 0.0 0% 0.2 12% 0.0 12%LP-15 39.3 100% 34.1 100% 39.1 100% 39.3 100%

June Second Quarter 2017April MayDewatering Wells



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, Southeast, or Pittsmont Sectors.

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.

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PZF12-6Abandoned

PZF12-5

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

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PZF12-5

Documents

Atlantic Richfield Company• Field trial on the Berkeley Pit on May 9, 2017 where a vertical profile was completed to a depth of 625 feet and a sample was collected at a depth of