PWS_-_Seed_Task_Order_20171017.pdf

Performance Work Statement For Remedial Action Contract

Seed Task Order

Callahan Mine Superfund Site

Brooksville Maine

14 September 2017 17 October 2017

1. Contract Procurement Objectives and Overview

The contract awarded under this solicitation will be an Indefinite Delivery/Indefinite Quantity contract for various Environmental Remediation Services in support of the US Army Corps of Engineers (USACE) at the Callahan Mine Superfund Site, Brooksville, Maine. The USACE has been retained by the United States Environmental Protection Agency (EPA) through IADW96- 958873 to implement the cleanup action for the Callahan Mine site. Project specific task orders will be issued under the basic contract. The USACE Contracting Officer or Project Manager will provide the Contractor with site-specific information in the USACE's possession upon issuance of each task order.

The Contractor shall perform all the necessary services required to successfully meet all performance objectives of this Performance Work Statement (PWS). The Contractor shall comply with all applicable Federal, State, and local laws and regulations in order to successfully complete all performance objectives of this PWS in a manner that is consistent with any applicable orders and permits and relevant Department of Defense (DOD) and Army policies for the duration of this Task Order. The Contractor shall also comply with all applicable requirements of the EPA Record of Decision for the Callahan Mine Superfund Site dated September 30, 2009, as modified by the Callahan Mine Superfund Site Explanation of Significant Differences dated September 20, 2013 and any subsequent EPA Decision Documents relating to the Callahan Mine site remedial action. The Contractor shall comply with all applicable ASTM standards and USACE Engineering Manuals and Engineering Regulations including, but not limited to, the following references (and default to most recent version if different) when preparing the proposal and executing the work:

• OU3 Final Remedial Design, Basis of Design Report, Callahan Mine Superfund Site, AMEC

Environment and Infrastructure, Inc., 1 July 2015 (https://www.epa.gov/superfund/callahan).

• Final Operable Unit 1 Feasibility Study Report, Callahan Mine Superfund Site, MACTEC Engineering and Consulting, Inc., July 2009

• Final Remedial Investigation Report, Callahan Mine Superfund Site, MACTEC Engineering and

Consulting, Inc., April 2009

• Sample and Analysis Plan/Quality Assurance Project Plan, Credere and Associates, LLC, 29 Nov 2016

Record of Decision, Operable Unit 1, Callahan Mine Superfund Site, USEPA, September 2009 https://www.epa.gov/superfund/callahan

• Design Refinement Feasibility Evaluation, Callahan Mine Superfund Site, USACE, 31 May 2017 (Attached)

• Engineer Manual (EM) 1110-1-4007 Safety and Health Aspects of Hazardous, Toxic, and Radioactive Waste Remediation Technologies, USACE, 2003

• EM 200-1-3, Requirements for the Preparation of Sampling and Analysis Plans, USACE, 1 Feb 2001

• Engineer Regulation (ER) 1110-1-263, Chemical Data Quality Management for Hazardous, Toxic, Radioactive Waste Remedial Activities, USACE, 30 Apr 1998

• EM 200-1-6, Chemical Quality Assurance for HTRW Projects, USACE, 10 Oct. 1997 DOD Quality Systems Manual (QSM), for Environmental Laboratories, Revision 5.0 dated July 2013

• Uniform Federal policy for Quality Assurance Project Plans (UFP for QAPP), Evaluating, Assessing and Documenting Environmental Data Collection and Program Use, Part 1 and Part 2, Final version 1, March 2005

• Intergovernmental Data Quality Task Force Uniform Federal Policy for Quality Assurance Project Plans Optimized UFP-QAPP Worksheets. www.epa.gov/fedfac. DoD/EPA/DOE, March 2012

• EPA New England Environmental Data Review Program Guidance. Version 4-22-2013

• DoD General Data Validation Guidelines, Environmental Data Quality Workgroup, Dec 2016

• National Functional Guidelines for Superfund Organic Methods Data Review. EPA-540-R-2016-002

• National Functional Guidelines for Superfund Inorganic Methods Data Review. EPA-540-R-2016-001

• ER1180-1-6, Construction Quality Management, USACE, 30 Sep 1995

• EM 385-1-1 U.S. Army Corps of Engineers Safety and Health Requirements Manual (2008)

• Performance Standards for Quarries, Article 8-A of the Maine Revised Statues for Title 38: Waters and Navigation.

• EM 1110-1-4000, Monitoring Well Design, Installation, and Documentation at Hazardous Toxic, and

Radioactive Waste Sites, USACE, Dated November 1, 1998.

• 42 U.S. Code Chapter 103 – Comprehensive Environmental Response, Compensation, and Liability.

• EQASOP-GW 0001, Low Stress (low flow) Purging and Sampling Procedure for the Collection of

Groundwater Samples From Monitoring Wells, prepared by USEPA Region 1, dated July 30, 1996, revised January 19, 2010.

• ER 1110-1-8157, Engineering and Design Geotechnical Data Quality Management for Hazardous Waste Remedial Activities, 2002.

• EM 1110-1-1804 Geotechnical Investigations, Engineering and Design, 2001.

• EM 1110-1-1802 Geophysical Exploration for Engineering and Environmental Investigations, 1995.

• EM 1110-2-1902, Slope Stability, USACE, 31 October 2003.

• United States Environmental Protection Agency, 2006. Guidance on Systematic Planning Using the

Data Quality Objectives Process (EPA QA/G-4), Office of Environmental Information.

• U.S. Department of the Interior, Bureau of Reclamation, Engineering Geology Field Manual, Second

Edition, Volumes I and II, 1998, Reprinted 2001.

• U.S. Department of the Interior, Bureau of Reclamation, Earth Manual, 3rd Edition, Vol I and II, 1998.

• Applicable or Relevant and Appropriate Requirements (ARARS) from OU1 Record of Decision

• Applicable ASTM Standards

• Whole Building Design Guide Specifications, Section 01 45 00.00 10 Quality Control;

• Whole Building Design Guide Specifications, Section 01 45 00.15 10 RMS with Contractor Module;

• Whole Building Design Guide Specifications, Section 01 32 01.00 10 Project Schedule

• Whole Building Design Guide Specifications, Section 01 35 29.13 Health, Safety, and Emergency

Response Procedures for Contaminated Sites (Attached)

• Planning for Response Actions at Abandoned Mines with Underground Workings: Best Practices for

Preventing Sudden, Uncontrolled Fluid Mining Waste Releases, EPA, July 2017 http://www.epa.gov/fedfac

• Maine Stormwater Best Management Practices Manual and Maine Erosion and Sediment Control Best Management Practices (www.maine.gov/dep/land).

2.0 Types of Services Required

This Task Order includes the following types of geotechnical and environmental services as authorized under the basic contract:

- Site Characterization/Investigation

- Studies and Reports

- Monitoring and Interim Operations

- Engineering for Remediation

- Remedial Action

3.0 Contract Type

_X__ Cost Plus Fixed Fee _X__ Firm-Fixed Price ____ Fixed Price with Award Fee

4.0 Site Background

From 1968 through 1972, the Callahan Mining Corporation developed a massive sulfide ore body located beneath a bedrock peninsula that extended into Goose Pond. Goose Pond is a tidal estuary of approximately 75 acres located in the Town of Brooksville, ME. To gain access to the ore, the mouth of the estuary was dammed, and Goose Pond was drained. An open pit mine approximately 600 feet in diameter and 320 feet deep was excavated to access the ore. The trend of the mineralized zone was northeast- southwest, and underground workings to supplement the ore available from the pit were extended from the face of the open pit approximately 500 feet on two levels (adits) to the southwest. These adits are located approximately 120 feet below the current surface of Goose Pond. Approximately five million tons of waste rock and approximately 800,000 tons of ore-bearing rock were mined from an open-pit mine. The waste rock was disposed on-site in three large stockpiles.

Tailing material from the ore processing were deposited within an impoundment basin created at the site. The outside footprint of the Tailing Impoundment encompasses approximately 17-acres and contains about 725,000 cubic yards of mining related waste (tailing), including fine sand, silt, and clay-sized rock particles. The tailing are contained by a three-sided dam that was raised against a sloping hillside. Most of the dam is constructed of cobble and boulder-sized waste rock materials. The eastern side of the dam is about 60 feet tall and has an average slope of about 1.3H to 1V (horizontal to vertical). There is little information on the construction details of the tailing impoundment, and the disposal practices of the tailing material within the impoundment.

PCB contaminated soils from the Ore Pad, Mine Operations Area, and nearby residential homes were excavated under previous remedial actions and deposited on top of the Tailing Impoundment for future capping.

Remedial investigations have determined that both the Tailing Impoundment and Waste Rock Pile #3, and nearby sediment, contain metals contamination of sufficient concentration to require remedial action. Groundwater within the tailing impoundment is considered leachate.

Aluminum, arsenic, lead, sodium, and manganese were detected in excess of maximum contaminant levels (MCL) and Maine Exposure Guidelines (MEG) in tailings impoundment leachate. The leachate also contains cadmium, copper, and zinc above state and federal surface water quality standards. Sulfate and chloride concentrations were also elevated. Bedrock groundwater contains sodium and manganese in excess of MEGs. Lead was detected in excess of the MEG in the upgradient bedrock borehole. The Tailing Impoundment and Waste Rock Pile #3 are both adjacent to the Goose Pond Salt Marsh, creating a potential risk of significant ecological damage.

5.0 Task Order 1 (Seed Task Order) - Performance Objectives and Standards

This Task Order PWS is for a results-based contract with intent to successfully complete all performance objectives shown in Table 1. Based on estimated cost of work, approximately 75% of the tasks will be Cost Plus Fixed Fee (CPFF), and 25% of the tasks will be Firm Fixed Price (FFP). Table 1 identifies the tasks that will be CPFF and FFP. There will be a separate Contract Line Item Number (CLIN) for FFP tasks and for CPFF tasks.

The Contractor shall furnish all labor, materials and equipment necessary to successfully complete all performance objectives identified in this PWS and Table 1, Performance Requirements Summary. Achievement of the performance objectives is successfully attained upon the finalization of appropriate documentation certifying that the documents have been accepted by the CENAE. CENAE approval of the Performance Standards will be by the CENAE Contracting Officer (KO) or Contracting Officer’s Representative (COR).

Table 1 – Performance Requirements Summary Performance Objective/Task Performance Standard

Task 1- Project Management/Status Reports

FIRM FIXED PRICE

Submit Monthly Status Reports and Vouchers by 5th day of each month in accordance with program requirements and USACE acceptance

Task 2 – Submit Plans (FIRM FIXED PRICE) Task 2.1 – Prepare Project Management Plan USACE acceptance of Final Project Management Plan Task 2.2 – Prepare Work Plan USACE approval of Final Work Plan Task 2.3 – Prepare Accident Prevention Plan (APP) and Site Safety and Health Plan (SSHP)

USACE approval of Final APP/SSHP

Task 2.4 – Prepare Sampling and Analysis Plan (SAP) and Quality Assurance Project Plan (QAPP)

USACE approval of Final SAP/QAPP

Task 2.5 – Prepare Geotechnical Instrumentation and Monitoring Plan, Including Failure Modes and Effects Analysis

USACE approval of Final Geotechnical Instrumentation and Monitoring Plan

Task 2.6 – Prepare Quarry Design and Restoration Plan USACE approval of Final Quarry Design and Restoration Plan

Task 2.7 – Prepare Quality Control Plan USACE approval of Quality Control Plan Task 3 – Site Mobilization and Site Preparation – Establish Work Surfaces, Staging Areas, Erosion Controls, Ecological Resources Protection, Survey

Complete Site Mobilization and Site Preparation in accordance with approved Work Plan to achieve stable, safe, and protective work areas.

Table 1 – Performance Requirements Summary Performance Objective/Task Performance Standard

Controls, Security, Dust Control, and Surface Water Management. Install Baseline Geotechnical Monitoring and Air Monitoring Equipment

(FIRM FIXED PRICE)

Task 4 – Establish On-Site Quarry at Dyer Hill

(FIRM FIXED PRICE)

Establish rock quarry to safely drill, blast, and crush rock materials (~ 70,000 CY)

Task 5 – Reduce Dam Height

(COST PLUS FIXED FEE)

Cut back waste rock (~ 30,000 CY) at top of dam to achieve a minimum Factor of Safety of 1.3 during construction activities and 1.5 post construction activities. Dam face slope shall achieve minimum of 2H:1V on eastern face of the dam.

Minimize impacts to wetland at toe of slope.

Task 6 – Install Vertical Drains in Tailing Impoundment to Reduce Pore Pressures

(FIRM FIXED PRICE)

Install vertical drains to dissipate pore pressures throughout the entire tailing impoundment (both laterally and vertically).

Vertical drain selection and placement shall be designed to facilitate achievement of 90% consolidation within the tailings impoundment within a reasonable time period (not to exceed 30 days). All water collected from the vertical drains shall be treated to meet the Maine Saltwater Aquatic Life Criteria identified in Table 5-2 of the Basis of Design.Ambient Water Quality Standards

Task 7 – Re-grade Tailing Impoundment. Construct Drainage Swale at Top of Tailings Dam. Place Excavated Material on Top of Tailings Impoundment. Assume 80,000 CY of excavation.

(COST PLUS FIXED FEE)

Drainage swale shall intercept the water table. Side slopes shall achieve 3H:1V and meet required slope stability requirements (1.3 during construction, 1.5 post construction). Drainage swale shall provide sufficient capacity and pitch to prevent overflow of the swale banks during 100 year storm events. All stormwater shall be managed in accordance with Maine Stormwater Control and Erosion Best Management Practices. Placed material shall achieve 90% consolidation within the Tailing Impoundment between lifts to prevent excess pore pressure

Task 8 – Prepare Completion Report for Phase I of Remedial Action (FIRM FIXED PRICE)

Final Completion Report shall include summary of work completed, geotechnical results, analytical results, as-built drawings and an evaluation of the effectiveness of the slope stabilization measures. Final Completion Report shall be approved by USACE

Task 9 – Conduct Groundwater Monitoring

(FIRM FIXED PRICE)

Conduct groundwater monitoring in accordance with approved Sampling and Analysis Plan and QAPP. The Sampling and Analysis Plan and QAPP shall be similar to the existing SAP/QAPP Plan dated 29 November 2016.

Task 10 – Conduct Operations and Maintenance of Groundwater Treatment System and Sediment Pond

(FIRM FIXED PRICE)

Conduct Operations and Maintenance of Groundwater Treatment System in accordance with the Sampling and Analysis Plan/Quality Assurance Project Plan dated 29 November 2016.

Task 11 – Site Demobilization

(FIRM FIXED PRICE)

Demobilize equipment from Site in accordance with Work Plan

In the event that there may be multiple milestones and/or deliverables for each of the performance objective tasks, partial payments will be based on the successful completion of milestones. Final decisions regarding the adequacy of milestone and deliverable completion resides with the KO or COR.

6.0 Task Order Contract Requirements

The Contractor shall furnish all necessary labor, equipment, materials, and supplies to complete the tasks listed in Table 1 above and defined in the following paragraphs. All work shall be conducted in a safe, secure, cost efficient, and environmentally acceptable manner conforming to existing Federal, State, and local regulations. Work shall be completed correctly in a professional, workmanlike manner, in accordance with approved work plans. Work is to be performed commensurate with the level of effort and quality intended, with appropriately qualified quality control (QC) representation (as part of the contractors overall QC Program) controlling the work.

Period of Performance for all tasks under this Task Order is twenty-four (24) months from Notice to Proceed.

6.1 Task 1.0 – Project Management/Project Controls

This task provides for oversight of the below activities to include the Program Manager, Project Manager, Subcontracts Manager, Project Controls, Cost Scheduler, and Administrative staff when engaged in representative non-site specific activities.

• Cost and schedule reporting and tracking.

• Subcontractor cost and schedule reporting and tracking.

• Program resource planning selection and resource conflict resolution.

• Participation by the Project Manager and Construction Supervisor in monthly conference calls with Corps, staff, EPA, and subcontractors.

• Contract basis review, verification, and tracking of invoices to ensure conformance to applicable contract requirements.

• Preparation of monthly invoices.

• Preparation of daily update on field activities via e-mail.

• Preparation of weekly field update on field activities via e-mail.

6.2 Task 2.0 – Prepare Plans

6.2.1 Task 2.1 – Project Management Plan

The Contractor shall develop and maintain a detailed Project Management Plan (PMP). The PMP will specify the schedule, execution, and completion of the performance objectives. The first draft PMP shall be submitted within 30 calendar days of contract award. The draft PMP and subsequent revisions will be subject to USACE review and approval through the Contracting Officer’s Representative (COR). The final PMP will be due within fifteen (15) calendar days of comments received from the COR. Assume a Draft, Draft Final, and Final PMP. A payment milestone will be established for USACE approval of the final PMP through the COR.

As part of the PMP, the Contractor will develop and maintain an activity-based schedule that complies with 01 32 01.00 and fully supports the technical approach and outlines the due dates for all milestones and payable deliverables. A payment plan will be included with the schedule that allows for payments to the Contractor based on successful completion of interim milestones proposed by the Contractor. It is the USACE intent to make all payments after verification of progress in accordance with this schedule. As part of the PMP, the Contractor will identify and implement a means for providing project monthly status reports to the COR. The PMP will address the content of status reports.

6.2.2 Task 2.2 – Work Plan

The Contractor shall prepare a draft, draft-final and final work plan, prior to the commencement of any work on the project site. The Work Plan shall contain, but not be limited to, the following:

- Statement of the work to be accomplished including a statement of Data Quality Objective(s);

- Discussion on implementation of the project including the method of operation, type of equipment, personnel required, and other special considerations for the following tasks: site preparation, tailing impoundment dam height reduction and re-grading, excavation and construction of a drainage swale, collection and treatment of water from drainage swale, establishment of on-site quarry, vertical drain installation, geotechnical monitoring, groundwater sampling and analysis, and bio-reactor system operation and maintenance (Tasks 3-10)

- Technical Approach to accomplish slope stability within the Tailing Impoundment.

- Air Monitoring to ensure dust is adequately controlled to prevent fugitive dust emissions in compliance with regulatory standards.;

- A schedule detailing the work to be performed with key project milestones;

- Permits, licenses, access agreements, and certificates required;

- Key personnel to be used on the project along with their roles and responsibilities;

- Site-specific assumptions and clarifications;

- Logs, reports, and record keeping to be utilized

Assume a technical meeting will be conducted with all stakeholders approximately 45 days prior to submission of the Draft Work Plan to review proposed remediation approaches for inclusion in the Draft Work Plan. Assume draft, draft final, and final versions of the Work Plan will be required with response to comments (RTCs) and response to comments letters (RCL) by the Contractor after the draft submittal. Required technical specifications and drawings will be required to be submitted with Work Plan. Plans and specifications that are taken directly from the Basis of Design (without revision) can be referenced instead of re-submitted. Acceptance of the Contractor's work plan by the Government is required prior to any field mobilization.

Acceptance is conditional and will be predicated on satisfactory performance during field activities. Deviations or proposed changes to the approved Work Plan must be submitted to the USACE Project Manager or COR for review, comment, and approval. The Government reserves the right to require the Contractor to make changes in his Work Plan and operations as necessary.

During execution of the task order, the Contractor shall follow the approved Work Plan. The Work Plan, together with required Plans and Specifications, shall be submitted within 90 days of Notice to Proceed. The design work demonstrating compliance with the performance standards must be signed and stamped by a Professional Engineer. Any technical information developed to support the Plans and Specifications, which is not included in the Basis of Design Report, shall be included in the Work Plan.

6.2.3 Task 2.3 – Health and Safety Documentation

The Contractor shall prepare an Accident Prevention Plan (APP) specific to the activities being performed. The documentation shall include an Activity Hazard Analysis (AHA) for each phase of work as described below. All work shall be conducted in accordance with the APP, the U.S.

Army Corps of Engineers Safety and Health requirements Manual (EM 385-1-1, most recent edition), UFGS-01 35 29.13 (attached), and all applicable federal, state, and local safety and health requirements. A copy of EM 385-1-1 can be accessed electronically at Headquarters USACE website under publications using the following link:

http://www.publications.usace.army.mil/library/.

The APP shall detail how safety and health will be managed during the project. The APP shall address the requirements of applicable Federal, State and local safety and health laws, rules, and regulations. The Contractor shall comply with Federal Acquisition Regulation Clause No.

52.236-13 for Accident Prevention, which is added by reference. Special attention shall focus on the requirements of EM 385-1-1, specifically Section 01.A.12 through 01.A.17, Figure 1-2 AHA, and Appendix A, (Minimum Basic Outline for Accident Prevention Plan). The APP shall be developed by a qualified person. The contractor shall be responsible for documenting the qualified person’s credentials. Work shall not proceed until the APP has been reviewed by the USACE Designated Authority and deemed acceptable for use on the project.

The contractor must prepare a Site Safety and Health Plan (SSHP) that covers the 14 elements identified in EM385-1-1, Section 33.B.02. At a minimum, the SSHP shall contain the following elements: site description and contaminant characterization, safety and health hazard(s) assessment and risk analysis, safety and health staff organization and responsibilities, site specific training and medical surveillance parameters, personal protective equipment (PPE) and decontamination facilities with documented procedures for monitoring and sampling requirements, safety and health work precautions and procedures, site control measures, on-site first aid and emergency equipment, emergency response plans and contingency procedures (on-site and off-site), logs, reports, and record keeping. The SSHP shall be attached to the APP as an Appendix. SSHP elements adequately covered elsewhere in the APP need not be duplicated in the SSHP.

The APP shall interface with the Contractor's overall safety and health program. Any portions of the Contractor's overall safety and health program referenced in the APP shall be included in the applicable APP element and made site-specific. The USACE considers the Prime Contractor to be the "controlling authority" for safety and health of the subcontractors. Contractors are responsible for informing their subcontractors of the safety provisions under the terms of the contract, the penalties for noncompliance, and inspecting subcontractor operations to ensure that accident prevention responsibilities are being carried out. The Contractor shall ensure that its subcontractors, suppliers and support personnel follow all safety and health provisions established in the approved Site Safety and Health Plan (SSHP), APP and/or AHA.

The Contractor shall conduct a safety meeting at the project site on the first day of work, and whenever a new activity or phase of work begins. All safety meetings shall be documented.

Records of the safety briefings shall be submitted to the USACE Designated Authority weekly.

Activity Hazard Analysis (AHA)

An AHA shall be submitted for each major phase of work. A major phase of work is defined as an operation involving a type of work presenting hazards not experienced in previous operations.

The analysis shall define all activities to be performed, identify the sequence of work, the specific hazards anticipated, and the control measures to be implemented to eliminate or reduce http://www.publications.usace.army.mil/library/ each hazard to an acceptable level. Work shall not proceed on a phase of work until the AHA has been accepted by the USACE. A preparatory meeting shall be conducted by the contractor to discuss the AHA contents with all engaged in the activity. The preparatory meeting shall be conducted by the prime contractor and shall include all subcontractors and USACE on-site representatives. The AHA shall be continuously reviewed and revised to address changing site conditions or operations as appropriate.

Accident Reporting

All accidents and near misses shall be investigated by the Contractor. All work-related recordable injuries, illnesses and property damage accidents (excluding on-the-road vehicle accidents), in which the property damage exceeds $5,000.00, shall be verbally reported to the USACE within 24 hours of the incident. Serious accidents as described in EM 385-1-1 Section 01.D shall be immediately reported to the Government Designated Agent (GDA). ENG Form 3394 shall be completed and submitted to the GDA within five working days of the incident.

The Contractor shall complete the “USACE Contractor Monthly Summary Record of Injuries/Illness and Work Hour Exposure” (for prime and its subcontractors – obtain form from GDA) and forward the completed form to the GDA no later than close of business on the 5th calendar day of the following month. The form shall be transmitted by the prime contractor to the GDA electronically.

APP/SSHP must be submitted within 60 days of NTP.

6.2.4 Task 2.4 – Sampling and Analysis Plan and Quality Assurance Project Plan

A Sampling and Analysis Plan (SAP) shall be prepared in accordance with EM 200-1-3, dated February 1, 2001, or subsequent revision. The SAP shall be consistent with the Sampling and Analysis Plan dated 29 November 2016.. In addition, the SAP will be required to include a Quality Assurance Project Plan (QAPP), prepared in accordance with Uniform Federal Policy for Quality Assurance Project Plans (DTIC ADA 427785), dated March 2005 or subsequent revision. The Contractor shall also develop data quality objectives (DQOs) for all phases of required work from existing project documents, applicable state and federal guidance and directives, and own sources, and include them in the appropriate sections of the work plans.

Copies of the Contractor’s SOPs and appropriate field forms shall be included as part of the SAP. The SAP/QAPP shall include sampling and analysis of soil, sediment, surface water and groundwater.

SAP and QAPP must be submitted within 60 days of NTP.

6.2.5 Task 2.5 – Geotechnical Instrumentation and Monitoring Plan

The selected remedy for the Tailings Impoundment requires stabilization measures (e.g., dewatering and crest improvements) to improve stability, including the installation of geotechnical instrumentation at the perimeter toe and within the tailings impoundment. This instrumentation will be installed prior to construction to monitor stability, locally and globally, during construction. A Geotechnical Instrumentation and Monitoring Plan shall be submitted to document the instrumentation required and the monitoring frequency and duration.

The main components of the geotechnical monitoring include the following:

• Visually observe and document conditions within and around the impoundment during construction;

• Identify any additional geotechnical samples that will be necessary to be collected to supplement the existing geotechnical data for the Tailings Impoundment;

• Monitor horizontal/lateral deformation along the impoundment fill slope toe and along the outer perimeter/toe of the impoundment dam. Tools such as ground based light detection and ranging (LiDAR) and/or Radar Interferometry may be used to monitor deformation;

• Monitor piezometric water levels within the tailings impoundment prior to and during construction;

• Monitor pore pressure generation/dissipation in the tailings impoundment during fill placement;

• Monitor vertical settlement in the tailings impoundment during and following fill placement;

• Utilize the geotechnical monitoring data in conjunction with the visual observations to evaluate the response of the tailings impoundment during construction and to adjust the rate of fill placement, as necessary, to promote stability.

The tailings impoundment currently contains installed instrumentation. It is anticipated that the existing instrumentation will be utilized during remediation activities. Instrumentation in cut areas will likely be abandoned and/or removed during construction. The existing instrumentation, within and at the toe of the impoundment, consists of monitoring wells, observation wells, standpipe piezometers, and vibrating wire piezometers.

The following supplemental/additional instrumentation should be installed in support of the plan objectives as follows:

• Slope Inclinometers;

• Standpipe Piezometers;

• Vibrating Wire Piezometer (VWP) Locations; and

• Settlement Platforms.

The Geotechnical Monitoring and Instrumentation Plan shall include a Failure Modes Effects Analysis (FMEA) for the Tailing Impoundment work to be conducted under the Seed Task Order. The FMEA shall be conducted in accordance with the EPA guidance document “Planning for Response Actions at Abandoned Mines with Underground Workings: Best Practices for Preventing Sudden, Uncontrolled Fluid Mining Waste Releases”, dated July 2017.

A draft Geotechnical Monitoring Plan has been developed for the site and can be used as a guide by the Contractor (Appendix E of the Basis of Design) in developing the Geotechnical Instrumentation and Monitoring Plan.

The Contractor Geotechnical Instrumentation and Monitoring Plan shall be submitted within 90 days of NTP.

6.2.6 Task 2.6 - Quarry Design and Restoration Plan

The contractor shall be required to establish a quarry on-site to provide materials for drainage layers, cap layers, work surfaces, access roads, etc. A Design and Restoration Plan shall be prepared for the quarry. The Design and Restoration Plan shall include a section to address procedures for blasting operations (both Test Blasting and Operational Blasting), including safety procedures and vibration monitoring. A baseline survey of nearby properties shall be conducted prior to any blasting. A schedule for subsequent surveys to monitor and evaluate potential property damage shall also be included in the Design and Restoration Plan.

The Quarry Design and Restoration Plan shall include a section that describes the protective measures that will be implemented to include:

• A 100-foot wide buffer between area of excavation and property boundaries.

• A 100-foot wide buffer between the area of excavation and high-water line of Dyer

Pond.

• A pre-blast survey a minimum radius of ½ a mile from the blast site.

• A designated area for crushing and staging procedures.

• Chain link fence surrounding the construction area.

• Diversion swales to convey any stormwater runoff from the construction site to a sediment trap or stormwater detention pond.

• Noise control measures so that applicable noise limits are not exceeded.

• Dust control measures for control of fugitive emissions.

• Site restoration to a condition consistent with current existing conditions.

A fall/winter quarry operation is preferred to minimize impacts on local seasonal residences. The Quarry Design and Restoration Plan is required to be submitted within 90 days of NTP. Results of the Blast Test and the pre-blast survey shall be submitted to USACE within 30 days of completion of the Blast Test. No operational blasting shall occur until the results of the Blast Test and the pre-blast survey have been approved by USACE.

6.2.7 Task 2.7 – Quality Control Plan

The contractor shall submit a Quality Control Plan. Contractor Quality Control (CQC) is the means by which the Contractor ensures that the work, to include that of subcontractors and suppliers, complies with the requirements of the contract. The control shall be adequate to cover all operations, including both on-site and off-site activities. The Contractor is responsible for quality control and shall establish and maintain an effective quality control system. The quality control system shall consist of plans, procedures, and organization necessary to produce an end product that complies with governing regulations and contract task order requirements. The Contractor's quality control program shall include inspections and tests as described in the task orders. The contractor Quality Control program shall be consistent with Whole Building Design Guide Specification Section 01 45 00.00 10 Quality Control and Whole Building Design Guide Specification Section 01 45 00.15 10 RMS with Contractor Module.

The Quality Control Plan shall be submitted within 60 days of NTP.

6.3 Task 3 – Site Preparation

The contractor shall prepare the site for the remediation work in accordance with the USACE approved Work Plan. The following activities will be conducted under this task:

Trailer setup for both contractor and Government with temporary utilities, sewer, water, electrical and telephone;

Extend electrical, telephone, and internet service 750’ from existing pole location Establishment of vehicular traffic pathways, staging areas, and lay-down areas;

Implementation of the air monitoring plan;

Implementation of the Geotechnical baseline monitoring plan;

Soil and sediment erosion controls;

Stormwater controls and treatment;

Stabilization measures, as necessary;

Installation of security fencing, and Establishment of exclusion zones, reduction zones and support zones throughout the execution of remediation activities

The placement of fill over very soft slimes in the central portion of the Tailings Impoundment will require the construction of an initial working surface/pad. This working surface will be necessary to allow placement of subsequent lifts of fill, as well as to allow installation of the vertical drains (Task 6) and geotechnical instrumentation. The aerial extent of the working surface is shown in the Design Drawings in the OU3 Final Remedial Design - Basis of Design.

A conceptual evaluation was performed to assess the feasibility of constructing a working surface to support the low ground pressure equipment that the contractor will likely need to perform the work. This evaluation identified several items that will be necessary in order to construct the working surface. The items are as follows:

• A non-woven geotextile on the existing tailings surface to act as a separation between the tailings and surficial organics and the high permeability drainage layer above it;

• A geogrid reinforcement layer to support the weight of the fill and equipment;

• A one foot thick, highly permeable drainage layer consisting of crushed stone from quarrying operations on site, meeting the requirements of Maine DOT 703.02 gradation AA ¾ inch Crushed Stone;

• A surface layer of 1 to 3 feet of additional crushed stone (D50 of approximately 1 to 2 inches), with thickness and gradation depending on the type and size of equipment the contactor proposes to use to construct the working pad and install the vertical drains and instrumentation;

• The vertical drains shall be installed following the construction of the working surface, and terminated within the working surface, or additional crushed stone should be placed around and atop the vertical drain terminations for drainage and protection; and

• Additional geotechnical instrumentation shall be installed after the working pad has been constructed and the vertical drains have been installed.

Conceptual/Example working surface calculations are presented in Appendix I. A conceptual design detail is presented in the Design Drawings. The contractor will be required to include the site preparation details in the Work Plan (Task 2.2).

6.4 Task 4 – Establish On-Site Quarry

The contractor shall establish an on-site quarry to minimize the importation of large volumes of construction materials. The quarry area will be located at Dyer Hill, west of the Ore Pad Haul Road. Processed material for the Tailings Impoundment remediation will be produced through drilling, blasting, and crushing of virgin bedrock. Waste rock removed from the Tailings Impoundment may also be processed to produce materials for placement beneath the infiltration cap barrier such as the working surface platform. The Contractor mus t develop means and methods to most effectively produce the required materials for the project. The contractor will be required to provide a full Quarry Design and Restoration Plan (see Task 5.2.6) that complies with state and federal regulations, primarily following the Performance Standards for Quarries, Article 8-A of the Maine Revised Statues for Title 38:

Waters and Navigation.

The onsite quarry and crushing operations will provide all stone and gravel materials necessary to complete the Tailings Impoundment remedy. It is estimated that approximately 70,000 cubic yards of rock could be produced during excavation and blasting from this area. Additional crushed stone may be produced from tailings impoundment waste rock and utilized for working surface material to be installed below the infiltration cap barrier. Actual volumes produced will be based on Contractor means and methods to provide the required material from on-site resources. Table 10-1 summarizes the anticipated materials and estimated volumes to be produced. Assume a volume of 70,000 cubic yards of rock will be extracted from the quarry.

Per the Basis of Design Report, the quarry includes an area of abundant andesite that should be amenable for removal from the quarry. The area to the north of the quarry is dominated by rhyolite, which would be more difficult to remove. Figure 3.1.2 in the RI report shows the bedrock outcrop mapping at the site. Page 10-1 of the Basis of Design Report discusses the bedrock mapping. Drawing C-117 of the Basis of Design Report shows the conceptual location of quarry area (andesitic/dioritic rock).

Table 2 On-Site Quarry Summary

Material Type Estimated Volume (CY) Working / Drainage Surface 27,000

Crushed Access Road Gravel 3,000

Underdrain Gravel 15,000

Reface Dam (must be clean quarry rock) 25,000

Total 70,000

Although the requirement for rock is estimated at 70,000 cubic yards, it is possible that some of the loose rock existing at the site could be suitable to be re-used within the tailing impoundment. As a result, the actual amount of rock that needs to be quarried could be lower than 70,000 cubic yards. Due to the uncertainty regarding the amount of rock that needs to be quarried, the contractor shall provide a unit cost for a quantity of 50,000 cubic yards of rock to be quarried. The contractor shall also provide a second unit cost for an additional 35,000 cubic yards of rock to be quarried.

The onsite quarrying and crushing approach was chosen to utilize natural resources and minimize the amount of heavy-truck traffic bringing material onto the site over the narrow and twisting local roads. The quarry procedures will result in construction related concerns (e.g. natural resource encroachment, noise, dust, erosion and sediment transport, reclamation, and blasting) which will be controlled under the design guidelines listed in the Performance Standards for Quarries, Article 8-A.

6.5 Task 5 - Reduce Height of Tailings Impoundment Dam

The tailings impoundment contains about 725,000 cubic yards of mining related waste, including fine sand, silt, and clay-sized rock particles (i.e., tailings) from the Callahan-era mining operations. The tailings are contained by a three-sided dam that was raised against a sloping hillside. Most of the dam is constructed of cobble and boulder-sized waste rock materials. The eastern side of the dam is about 60 feet tall and has an average slope of about 1.3H to 1V (horizontal to vertical). Based on geotechnical analysis completed to date, the dam as currently constructed does not achieve the construction minimum factor of safety (1.3) and the standard long term factor of safety (1.5). The face of the dam is very steep with an average slope of 1.3H:1V, also contributing to the instability of the dam.

Under this task, the height of the dam will be lowered to reduce the load on the dam. The objective of the dam height reduction (together with the tailings excavation under Task 7) is to achieve the construction factor of safety and the long term slope stability factor, and seismic load safety factor (1.0). Based on the OU3 Remedial Design Basis of Design Report dated July 1, 2015, and the USACE Memorandum dated 19 December 2016, lowering the dam height by approximately 15-20 feet will result in achievement of the required slope stability Factors of Safety. The contractor will be required to demonstrate in the Work Plan that their proposed approach achieves the required slope stability Factors of Safety.

Waste rock removed from the tailings impoundment perimeter berms that is greater than 12” in diameter shall be transported to the on-site quarry area located along the west side of the former mining operations area. Waste rock may be processed through crushing operations to produce crushed stone materials to be used in the construction of the working platform across the “slimes” area within the t ailings i mpoundment. Berm rock removed from the tailing impoundment berm that is smaller than 12” in diameter may be placed directly on the tailing impoundment for use as a drainage layer, working platforms, or surcharge. The proposed working platform will remain in place during fill placement and eventually be covered with an infiltration barrier cap.

Rock from the on-site quarry shall be used to re-slope the rock face on the eastern side of the dam to achieve a 2:1 slope (assume 25,000 CY) and fill in holes in the existing rock face. To the extent feasible, wetland impacts at the toe of the slope shall be minimalized in the placement of the rock.

Geotechnical monitoring shall be conducted in accordance with the Geotechnical Monitoring Plan during this phase of work to ensure that the Tailings Impoundment remains stable.

6.6 Task 6 – Install Vertical Drains in Tailing Impoundment to Reduce Pore Pressures

The OU3 final Remedial Design - Basis of Design includes an evaluation to determine the spacing requirements for the proposed vertical drains to be installed within proposed fill areas of the tailings impoundment (Appendix G). The results of the settlement evaluation indicate that an average of approximately 17 inches of settlement will occur under the weight of the proposed fill. The staged construction stability (presented in Appendix J) relies on the efficient dissipation of excess pore pressures so that additional lifts of fill can be placed safely. Vertical drains will be required in fill areas (on top of the impoundment) to accelerate consolidation for constructability purposes. Assume the drains will be installed to a depth of 30 feet. The vertical drain evaluation assessed the time to achieve 90 percent of the average consolidation through radial drainage. The vertical drain evaluation was performed using methods outlined in FHA (1986) and Bergado, et al (1996). The vertical drain used in developing the design was a 3-inch diameter Earthquake (EQ) Drain manufactured by Hayward-Baker (HB) Wick Drains. The contractor may choose a suitable alternative, but the performance of the alternative vertical drain must be comparable. Supporting documentation for the alternative vertical drain and spacing design must be provided in the Work Plan.

In the Basis of Design, it was determined that an EQ Drain spacing of 6 feet will allow the tailings to achieve an estimated 90 percent average consolidation in 12 to 28 days, based on a coefficient of vertical consolidation (cv) of 1.0 ft2/day (based on evaluation of site-specific laboratory consolidation testing data and published values; see Appendix G, Attachment G-1) and a range in the horizontal coefficient of consolidation (ch) of 1 to 5 ft2/day. The calculations supporting the EQ Drain evaluation are included in Attachment H of the Basis of Design.

The EQ Drains will also allow pore pressures in saturated tailings to dissipate quickly, providing protection against liquefaction in the event of an earthquake. However, the recommended EQ Drain spacing above was based solely on accelerating pore pressure dissipation for construction, not in the event of a design magnitude earthquake.

Water collected from the EQ Drains shall be treated by the on-site bio-reactor treatment system.

At times, the capacity of the bioreactors may be exceeded and alternative holding storage will be required until the treatment system can handle the flow.

The recommended EQ Drain layout and details are provided in the Design Drawings in Appendix M and Appendix N of the Basis of Design Report.

6.7 Task 7 – Re-grade Tailings Material and Construct Drainage Swale

The tailings impoundment contains mine processing waste materials. The tailings material is generally coarser on the outer portions of the impoundment, and becomes finer closer to the center of the impoundment. The elevation of water within the tailings impoundment is approximately 70’ MSL at the West Side of the impoundment, decreasing to approximately 50’ MSL at the East Side of the impoundment. Under this task, a drainage swale shall be created along the top of the dam. The drainage swale shall be constructed to intercept the water table within the tailings impoundment. The sides of the drainage swale shall achieve a 3H:1V slope. The swale shall be sized to prevent overflow of the swale banks during 100 year storm events. Stormwater collection and management from the drainage swale shall be conducted in accordance with Maine Stormwater Best Management Practices Manual and Maine Erosion and Sediment Control Best Management Practices (www.maine.gov/dep/land).

The tailings material that is excavated (assume 80,000 CY) shall be placed on top of the tailings impoundment in the “slimes” area (west of the swale excavation). The slimes must achieve 90% consolidation between each lift. Assume 32 lifts of 2 feet each for placement of the excavated material. Placement of excavated tailings across the “slimes” area will require the construction of a working platform to provide the necessary stability for construction equipment access (Task 3). The working platform will consist of an underlying crushed stone drainage layer, reinforcing geogrid, and a gravel working surface. The drainage layer will collect discharge from the v ertical drains (Task 6) to be installed within the “slimes” area to dissipate pore water pressure developed during fill placement. The crushed stone layer shall be installed to slope towards pre-determined sump locations and/or the constructed drainage swale. The rate of fill placement within the “slimes” area will be controlled based on geotechnical monitoring of pore water pressure.

There is an existing historical 6 inch cast iron decant pipe that extends from the western edge of the tailing impoundment and discharges in the proximity of seep SP-511. The discharge location was confirmed by dye testing as the discharge point within the dam face could not be physically determined. The decant pipe shall be sealed to prevent water intrusion and potential weakening of the tailing impoundment.

6.8 Task 8 – Prepare Completion Report

The contractor shall prepare a Final Completion Report to summarize the work completed, geotechnical monitoring results, air monitoring results, groundwater monitoring results, analytical results, as-built drawings and an evaluation of the effectiveness of the as-built slope stabilization measures. In addition, results of the quarry blast monitoring shall be included in the Completion Report. Assume internal draft, regulatory draft, draft final and final versions will be required with response to comments (RTCs) and response to comments letters (RCL) by the

Contractor. The Completion Report shall be approved by USACE. The Completion Report is due 60 days after construction is completed.

6.9 Task 9 – Perform Groundwater Monitoring

The contractor shall conduct groundwater monitoring at the site in accordance with Sampling and Analysis Plan, Callahan Mine Groundwater Monitoring Program developed under Task 2.4.

The following wells shall be sampled as a part of this task:

MW-602D MW-607 MW-615R

MW-602S MW-607R MW-617R

MW-603D MW-608 MW-618R

MW-603S MW-609R MW-711

MW-604D MW-610 MW-713