APP Hearings APP Hearings Rosemont Copper Project Rosemont Copper - - PowerPoint PPT Presentation

APP Hearings APP Hearings

Rosemont Copper Project Rosemont Copper Project By Troy Meyer, P.E. By Troy Meyer, P.E.

ROSEMONT-12 T. Meyer Power Point Presentation

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that the provisions in § 3.6.1 of the HLF Technical Specifications (Volume I) are contradictory. In Attachment A2, Pima County alleges that ADEQ erred by approving contradictory technical specifications for liner bedding fill below the Heap Leach Pad (HLP) and that ADEQ erred by approving incomplete Construction Quality Assurance (CQA) plans for the Heap Leach Facility (HLF). Attachment F, Item #4 There was an oversight/error in the technical

• specifications. The Issue For Construction (IFC) plans

will include revised specifications excluding the following text “The maximum particle size in the fill shall be no larger than two-thirds the fill compacted lift thickness, unless otherwise approved by the Engineer.” found in the section related to Liner Bedding Fill.

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County claims that ADEQ erred in approving an incomplete CQA Plan and associated technical specifications regarding the base liner system application, deployment and documentation for the Heap Leach Facility. Pima County claims that a “geotextile protection layer is needed directly on top of the geo-membrane liner” Attachment F, Items #2 and 3 1) The statement that “Soil particles coarser than 1 cm (3/8 inch) should never be placed directly on a geomembrane without first placing a suitable nonwoven needlepunched geotextile as a protection layer” is taken from a general geosynthetic design guideline developed by a geosynthetic manufacturer (GSE) and is not specific to heap leach applications. 2) Placement of a geotextile over a heap leach geomembrane is never done (we are not aware of any heap leach pads constructed in this way) because the resulting geotextile/geomembrane interface shear strength would be very low (below 10 degrees) and would cause the ore pile to be physically unstable. This must obviously be avoided to ensure the integrity of the liner containment system (eg, if the ore pile slumps or fails, the liner would be damaged resulting in possible uncontrolled release of process fluids).

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County claims that ADEQ erred in approving an incomplete CQA Plan and associated technical specifications regarding the base liner system application, deployment and documentation for the Heap Leach Facility. Pima County claims that a “geotextile protection layer is needed directly on top of the geo- membrane liner” Attachment F, Items #2 and 3 3) Protection of the liner system from puncture is ensured in the following ways:

• Laboratory testing of the liner system has been

completed to simulate ore loading to 150% of the maximum ore pile height and provides for an effective minimum factor of safety (FoS) against liner puncture of 1.5. The testing results indicated satisfactory performance of the proposed liner system.

• A test fill program will be developed and conducted

prior to construction of the heap leach liner system to simulate placement of the overliner gravel and haul truck traffic on the overliner. The CQA Engineer will provide oversight and document the results of the test fill and develop final procedures for overliner placement to ensure protection of the liner during leach pad

• construction. The test fill is required by the technical

specifications Section 3.7.2 which reads in part “Methods shall be developed onsite for placing the material in a manner that will protect the geomembrane and/or pipework from damage”

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that (i) “CQA Plan and Technical Specifications should discuss the need and preliminary design for anchor benches/trenches within the interior of the heap leach pad areas …;” Attachment F, Item #5 The heap leach pad liner system design includes anchor trenches along the perimeter of the pad. Details of the anchor trenches are provided on Drawing 080-CI-923. The placement of overliner gravel on the geomembrane will provide interior anchoring against wind uplift. The geomembrane liner will not be left exposed but will be immediately covered by the overdrain gravel.

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that (ii) “the technical specifications are insufficient by not specifying Geosynthetic Clay Liner information relating to manufacturer, installer experience, delivery, and conformance testing, among

• ther things;”

Attachment F, Item #6 Section 4.3.1 of the technical specifications clearly states the material requirements of the GCL and states that “The GCL material shall be sampled and tested in accordance with the Manufacturer’s approved QC Manual.” Section 9 of the CQA plan states “Conformance of the GCL to the Technical Specifications shall be verified by the CQA Consultant. Individual test methods shall be clearly stipulated and communicated to the parties involved with testing” Section 4.3.2 of the technical specifications provides detailed installation instructions for the GCL including subgrade acceptance, deployment, covering and protection, seam

• rientation and overlaps, and repairs. Deployment of GCL

does not require any special contractor qualifications as it does not involve specialized equipment or skills. The General (Earthwork) Contractor typically can complete this task, with

• bservation and documentation (panel surveys, photos, as-built

drawings, etc.) provided by the CQA Engineer. This section of the specifications also states “GCL shall not be covered prior to inspection and approval by the CQA Engineer.”

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that (iii) the Technical Specifications failed to specify “how a proper determination of GCL seam

• verlap is performed on a

daily basis during deployment;” Attachment F, Item #7 Section 4.3.2 of the technical specifications provides detailed installation instructions for the GCL including the following statement “Panels shall be positioned with the seam overlap not less than six (6) inches after shrinkage for longitudinal seams and two (2) feet after shrinkage for end-of-panel seams”. The wording of this requirement suggests that the overlap does not account for hydration shrinkage, when in fact it does. According to the manufacturer of the specified GCL, the minimum acceptable overlap is 6 inches. This is consistent with recommendations in ASTM D 6102 “Standard Guide for Installation of Geosynthetic Clay Liners” which accounts for research related to hydration shrinkage of GCL panels. A potential industry-wide concern for GCL shrinkage was identified by Thiel and Richardson based on observed problems at several sites worldwide. All of the known problems were for installations where an exposed geomembrane/GCL composite installation was left unballasted (that is, with no overlying cover soil) for an extended time. It has generally been accepted in the industry that a minimum of 12in. of cover soil will preclude further GCL shrinkage and that ballast should be added within 30 days. Since industry standards have not provided specific guidance to address this issue and it is currently unknown how long the liner will be left unballasted at Rosemont, we are proposing that the specification be modified to include heat tacking of the GCL seams to mitigate against shrinkage gaps developing following gemembrane deployment and prior to ballasting with overliner material. This approach has been used with proven success at several sites, including Carlotta heap leach in Arizona.

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that (iv) the specifications failed to address “facility base lining system,” liner material and attendance of the GCL installer at project construction meetings;” Attachment F, Item #8 Section 6.1.2 of the CQA Plan requires that the Pre- Construction Meeting, Resolution Meetings, Progress Meetings and Action Decision Meetings be attended by the Project Manager, the CQA Site Superintendent, the Earthwork Contractor, the Geomembrane Installer and other involved

• parties. The GCL installer will most likely be the General

(Earthwork) Contractor or the Geomembrane Installer. During deployment of the liner system, the GCL installer would certainly qualify as an “involved party”. Deployment of GCL does not require any special contractor qualifications as it does not involve specialized equipment or skills. The General (Earthwork) Contractor typically can complete this task, with

• bservation and documentation (panel surveys, photos, as-built

drawings, etc.) provided by the CQA Engineer. Section 4.3.2 of the specifications states “GCL shall not be covered prior to inspection and approval by the CQA Engineer.” Section 9 of the CQA Plan states “Conformance of the GCL to the Technical Specifications shall be verified by the CQA Consultant.” Thus, the CQA Engineer is responsible for the proper installation and documentation of the GCL for the heap leach pad.

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENC E SUBJECT/TESTIMONY Pima County argues that (v) the CQA Plan lacks provisions regarding acceptance of soil subsurface conditions, verification of seams, and verification of installation in accordance with the project documents;” Attachment F, Item #9 Section 4.3.2 of the specifications states “GCL shall not be covered prior to inspection and approval by the CQA Engineer.” Section 9 of the CQA Plan states “Conformance of the GCL to the Technical Specifications shall be verified by the CQA Consultant.” Section 3.3 of the specifications states “The subgrade shall be prepared to the satisfaction of the Engineer.” Thus, the CQA Engineer is responsible for the proper installation and documentation of the GCL for the heap leach pad. Section 4.3.2 of the technical specifications also provides detailed installation instructions for the GCL including subgrade acceptance, deployment, covering and protection, seam orientation and

• verlaps, and repairs. Deployment of GCL does not require any

special contractor qualifications as it does not involve specialized equipment or skills. The General (Earthwork) Contractor typically can complete this task, with observation and documentation (panel surveys, photos, as-built drawings, etc.) provided by the CQA Engineer. The elements for GCL field seam CQA are straight-forward and require only visual inspection by the CQA Engineer. The upper surface of the GCL has two heavy dashed lines on both sides of the

• panel. The lap lines are 6 inches from the edges of the panel, and

the match lines are 10 inches from the edges of the panel. Thus, the installer's objective is to place the overlying panel between the two lines of the underlying panel. The CQA engineer needs only to visually verify that the 6-inch lap line of the underlying panel is not

• visible. A properly executed seam, therefore, is verified when three

dashed lines (not four) are visible at the overlap.

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that (vi) the CGA Plan fails to mention the GCL liner installer in the documentation section and “the comprehensive set of CQA logs is considered incomplete;” Attachment F, Item #10 Section 10 of the CQA Plan states “The CQA Consultant will ensure that all quality assurance requirements have been addressed and satisfied.” This includes all requirements in the CQA Plan and the Technical Specifications for all installed/constructed items in the Construction Plans (not just the geomembrane). The CQA Plan also addresses CQA procedures for earthworks, pipework, concrete, and associated appurtenant items. The procedures include verification of material specifications, sampling and testing of materials at specified frequencies, remedial actions, and documentation of the construction and CQA results. Additionally, the technical specifications state that “All materials utilized are subject to approval by the Engineer” and requires the contractor to construct test fills, formally submit material specifications and shop drawings, and construction procedures for the Engineer’s approval.

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that (vii) the “CQA Plan omits requirements for documentation and logging related to a ‘photographic record of construction;’ Attachment F, Item #11 Section 10 of the CQA Plan states “The CQA Site Superintendent will maintain, at the job site, a complete file of Drawings and Technical Specifications, the CQA Plan, checklists, standard test procedures, daily logs, and other pertinent documents.” A photographic record of the construction would be considered a “pertinent document” and would be updated by the CQA personnel on a daily basis over the course

• f the construction.

Section 12 of the CQA Plan requires the CQA Consultant to keep a “photographic record of construction” to be included in the CQA Final Report. It is expected that this will include all aspects of construction pertinent to CQA for the heap leach, raffinate pond, PLS and stormwater ponds and all other aspects under the purview of the CQA Consultant.

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that (viii) the record of construction quality assurance activities is incomplete;” Attachment F, Item #12 Section 10 of the CQA Plan states “The CQA Consultant will ensure that all quality assurance requirements have been addressed and satisfied.” This includes all requirements in the CQA Plan and the Technical Specifications for all installed/constructed items in the Construction Plans (not just the geomembrane). The CQA Plan also addresses CQA procedures for earthworks, pipework, concrete, and associated appurtenant items. The procedures include verification of material specifications, sampling and testing of materials at specified frequencies, remedial actions, and documentation of the construction and CQA results. Additionally, the technical specifications state that “All materials utilized are subject to approval by the Engineer” and requires the contractor to construct test fills, formally submit material specifications and shop drawings, and construction procedures for the Engineer’s approval.

Heap Leach Facility Heap Leach Facility

WITNESS ISSUES AND TESTIMONY WITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY Pima County argues that (ix) the list of record drawings fails to include all critical elements of BADCT construction for the Heap Leach Facility;” (ix) the list of record drawings fails to include all critical elements of BADCT construction for the Heap Leach Facility;” Attachment F, Items #13 & 14 Although not explicitly stated in the CQA Plan, the record drawings would be expected to include all elements of the construction of the heap leach and associated facilities including the raffinate, PLS and stormwater ponds and all pertinent components and phases of construction. Although not explicitly stated in the CQA Plan, the record drawings would be expected to include a complete construction photographic record.