Meyer Revised Power Point - Maryland Office of ... · recommendations in ASTM D 6102 “Standard...

APP HearingsAPP Hearings

Rosemont Copper ProjectRosemont Copper Project

By Troy Meyer, P.E.By Troy Meyer, P.E.

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ROSEMONT-135 Meyer Revised Power Point

Heap Leach FacilityHeap Leach Facility

WITNESS ISSUES AND TESTIMONYWITNESS ISSUES AND TESTIMONY

ISSUE REFERENCE SUBJECT/TESTIMONY

Pima County argues that theprovisions in § 3.6.1 of the HLFTechnical Specifications (Volume I)are contradictory.

In Attachment A2, Pima Countyalleges that ADEQ erred byapproving contradictory technicalspecifications for liner bedding fillbelow the Heap Leach Pad (HLP)and that ADEQ erred by approvingincomplete Construction QualityAssurance (CQA) plans for theHeap Leach Facility (HLF).

Attachment F,Item #4

There was an oversight/error in the technicalspecifications. The Issue For Construction (IFC) planswill include revised specifications excluding the followingtext “The maximum particle size in the fill shall be nolarger than two-thirds the fill compacted lift thickness,unless otherwise approved by the Engineer.” found inthe section related to Liner Bedding Fill.

The construction Technical Specifications have beenrevised by Tetra Tech and reissued to ADEQ with theabove changes. The revised document is title“Rosemont Copper Project Dual Phase Heap LeachFacility Technical Specifications” and is dated February2012. The revised Liner Bedding Fill materialrequirements and placement procedures can be found inSection 3.8.




Pima County claims thatADEQ erred in approving anincomplete CQA Plan andassociated technicalspecifications regarding thebase liner system application,deployment anddocumentation for the HeapLeach Facility.

Pima County claims that a“geotextile protection layer isneeded directly on top of thegeo-membrane liner”

Attachment F,Items #2 and 3

1) The statement that “Soil particles coarser than 1 cm (3/8inch) should never be placed directly on ageomembrane without first placing a suitable nonwovenneedlepunched geotextile as a protection layer” is takenfrom a general geosynthetic design guideline developedby a geosynthetic manufacturer (GSE) and is notspecific to heap leach applications.

2) Placement of a geotextile over a heap leachgeomembrane is never done (we are not aware of anyheap leach pads constructed in this way) because theresulting geotextile/geomembrane interface shearstrength would be very low (below 10 degrees) andwould cause the ore pile to be physically unstable. Thismust obviously be avoided to ensure the integrity of theliner containment system (eg, if the ore pile slumps orfails, the liner would be damaged resulting in possibleuncontrolled release of process fluids).




Pima County claims that ADEQerred in approving an incompleteCQA Plan and associated technicalspecifications regarding the baseliner system application,deployment and documentation forthe Heap Leach Facility.

Pima County claims that a“geotextile protection layer isneeded directly on top of the geo-membrane liner”

Attachment F,Items #2 and 3

3) Protection of the liner system from puncture isensured in the following ways:

•Laboratory testing of the liner system has beencompleted to simulate ore loading to 150% of themaximum ore pile height and provides for an effectiveminimum factor of safety (FoS) against liner puncture of1.5. The testing results indicated satisfactoryperformance of the proposed liner system.

•A test fill program will be developed and conductedprior to construction of the heap leach liner system tosimulate placement of the overliner gravel and haultruck traffic on the overliner. The CQA Engineer willprovide oversight and document the results of the testfill and develop final procedures for overliner placementto ensure protection of the liner during leach padconstruction. The test fill is required by the technicalspecifications Section 3.7.2 which reads in part“Methods shall be developed onsite for placing thematerial in a manner that will protect the geomembraneand/or pipework from damage”




Pima County argues that(i) “CQA Plan and TechnicalSpecifications should discuss theneed and preliminary design foranchor benches/trenches within theinterior of the heap leach pad areas…;”


The heap leach pad liner system design includes anchortrenches along the perimeter of the pad. Details of theanchor trenches are provided on Drawing 080-CI-923.The placement of overliner gravel on the geomembranewill provide interior anchoring against wind uplift. Thegeomembrane liner will not be left exposed but will beimmediately covered by the overdrain gravel.




Pima County argues that(ii) “the technicalspecifications are insufficientby not specifyingGeosynthetic Clay Linerinformation relating tomanufacturer, installerexperience, delivery, andconformance testing, amongother things;”


Section 4.3.1 of the technical specifications clearly states thematerial requirements of the GCL and states that “The GCLmaterial shall be sampled and tested in accordance with theManufacturer’s approved QC Manual.” Section 9 of the CQAplan states “Conformance of the GCL to the TechnicalSpecifications shall be verified by the CQA Consultant.Individual test methods shall be clearly stipulated andcommunicated to the parties involved with testing”

Section 4.3.2 of the technical specifications provides detailedinstallation instructions for the GCL including subgradeacceptance, deployment, covering and protection, seamorientation and overlaps, and repairs. Deployment of GCLdoes not require any special contractor qualifications as it doesnot involve specialized equipment or skills. The General(Earthwork) Contractor typically can complete this task, withobservation and documentation (panel surveys, photos, as-builtdrawings, etc.) provided by the CQA Engineer. This section ofthe specifications also states “GCL shall not be covered prior toinspection and approval by the CQA Engineer.”




Pima County argues that(ii) “the technicalspecifications are insufficientby not specifyingGeosynthetic Clay Linerinformation relating tomanufacturer, installerexperience, delivery, andconformance testing, amongother things;”

Attachment F,Item #6 The CQA plan has been revised by Tetra Tech and reissued to

ADEQ to address this concern. The revised document is title“Rosemont Copper Project Dual Phase Heap Leach FacilityConstruction Quality Assurance (CQA) Plan” and is datedFebruary 2012. Section 4.3.2.2 of the revised CQA planrequires the GCL installer to provide documentation of GCLinstallation experience including a list of projects. Thisexperience will be verified during installer selection process.

Geosynthetic installation will be observed by representatives ofthe CQA Consultant and will include review and verification ofpanel layout and numbering.

Additional detail related to requirements for GCL manufactureand installation have been added to the revised CQA plan inSection 4.3.




Pima County argues that(iii) the TechnicalSpecifications failed tospecify “how a properdetermination of GCL seamoverlap is performed on adaily basis duringdeployment;”


Section 4.3.2 of the technical specifications provides detailedinstallation instructions for the GCL including the followingstatement “Panels shall be positioned with the seam overlap notless than six (6) inches after shrinkage for longitudinal seamsand two (2) feet after shrinkage for end-of-panel seams”. Thewording of this requirement suggests that the overlap does notaccount for hydration shrinkage, when in fact it does. Accordingto the manufacturer of the specified GCL, the minimumacceptable overlap is 6 inches. This is consistent withrecommendations in ASTM D 6102 “Standard Guide forInstallation of Geosynthetic Clay Liners” which accounts forresearch related to hydration shrinkage of GCL panels.

A potential industry-wide concern for GCL shrinkage wasidentified by Thiel and Richardson based on observed problemsat several sites worldwide. All of the known problems were forinstallations where an exposed geomembrane/GCL compositeinstallation was left unballasted (that is, with no overlying coversoil) for an extended time. It has generally been accepted in theindustry that a minimum of 12in. of cover soil will precludefurther GCL shrinkage and that ballast should be added within30 days. Since industry standards have not provided specificguidance to address this issue and it is currently unknown howlong the liner will be left unballasted at Rosemont, we areproposing that the specification be modified to include heattacking of the GCL seams to mitigate against shrinkage gapsdeveloping following gemembrane deployment and prior toballasting with overliner material. This approach has been usedwith proven success at several sites, including Carlotta heapleach in Arizona.




Pima County argues that(iv) the specifications failedto address “facility baselining system,” liner materialand attendance of the GCLinstaller at projectconstruction meetings;”


Section 6.1.2 of the CQA Plan requires that the Pre-Construction Meeting, Resolution Meetings, Progress Meetingsand Action Decision Meetings be attended by the ProjectManager, the CQA Site Superintendent, the EarthworkContractor, the Geomembrane Installer and other involvedparties. The GCL installer will most likely be the General(Earthwork) Contractor or the Geomembrane Installer. Duringdeployment of the liner system, the GCL installer would certainlyqualify as an “involved party”. Deployment of GCL does notrequire any special contractor qualifications as it does notinvolve specialized equipment or skills. The General(Earthwork) Contractor typically can complete this task, withobservation and documentation (panel surveys, photos, as-builtdrawings, etc.) provided by the CQA Engineer. Section 4.3.2 ofthe specifications states “GCL shall not be covered prior toinspection and approval by the CQA Engineer.” Section 9 of theCQA Plan states “Conformance of the GCL to the TechnicalSpecifications shall be verified by the CQA Consultant.” Thus,the CQA Engineer is responsible for the proper installation anddocumentation of the GCL for the heap leach pad.



ISSUE REFERENCE

SUBJECT/TESTIMONY

Pima County argues that(v) the CQA Plan lacksprovisions regardingacceptance of soilsubsurface conditions,verification of seams, andverification of installationin accordance with theproject documents;”

AttachmentF, Item #9

Section 4.3.2 of the specifications states “GCL shall not be coveredprior to inspection and approval by the CQA Engineer.” Section 9 ofthe CQA Plan states “Conformance of the GCL to the TechnicalSpecifications shall be verified by the CQAConsultant.” Section 3.3 of the specifications states “The subgradeshall be prepared to the satisfaction of the Engineer.”Thus, the CQA Engineer is responsible for the proper installationand documentation of the GCL for the heap leach pad.

Section 4.3.2 of the technical specifications also provides detailedinstallation instructions for the GCL including subgrade acceptance,deployment, covering and protection, seam orientation andoverlaps, and repairs. Deployment of GCL does not require anyspecial contractor qualifications as it does not involve specializedequipment or skills. The General (Earthwork) Contractor typicallycan complete this task, with observation and documentation (panelsurveys, photos, as-built drawings, etc.) provided by the CQAEngineer.

The elements for GCL field seam CQA are straight-forward andrequire only visual inspection by the CQA Engineer. The uppersurface of the GCL has two heavy dashed lines on both sides of thepanel. The lap lines are 6 inches from the edges of the panel, andthe match lines are 10 inches from the edges of the panel. Thus,the installer's objective is to place the overlying panel between thetwo lines of the underlying panel. The CQA engineer needs only tovisually verify that the 6-inch lap line of the underlying panel is notvisible. A properly executed seam, therefore, is verified when threedashed lines (not four) are visible at the overlap.



ISSUE REFERENCE

SUBJECT/TESTIMONY

Pima County argues that(v) the CQA Plan lacksprovisions regardingacceptance of soilsubsurface conditions,verification of seams, andverification of installation inaccordance with theproject documents;”

AttachmentF, Item #9

The CQA plan has been revised by Tetra Tech and reissued toADEQ to address this concern. The revised document is title“Rosemont Copper Project Dual Phase Heap Leach FacilityConstruction Quality Assurance (CQA) Plan” and is dated February2012.

Additional detail related to requirements for GCL manufacture andinstallation have been added to the revised CQA plan in Section 4.3.



ISSUE REFERENCE

SUBJECT/TESTIMONY

Section 9 of the CQA planreferences Table 1 of theTechnical Specifications

The referenced table is not numbered in the Technical Specificationsbut can be found under the section related to GCL materialrequirements (Section 4.3.1) of the revised Technical Specificationsdated February 2012.




Pima County argues that(vi) the CGA Plan fails tomention the GCL linerinstaller in thedocumentation section and“the comprehensive set ofCQA logs is consideredincomplete;”


Section 10 of the CQA Plan states “The CQA Consultant willensure that all quality assurance requirements have beenaddressed and satisfied.” This includes all requirements in theCQA Plan and the Technical Specifications for allinstalled/constructed items in the Construction Plans (not justthe geomembrane). The CQA Plan also addresses CQAprocedures for earthworks, pipework, concrete, and associatedappurtenant items. The procedures include verification ofmaterial specifications, sampling and testing of materials atspecified frequencies, remedial actions, and documentation ofthe construction and CQA results. Additionally, the technicalspecifications state that “All materials utilized are subject toapproval by the Engineer” and requires the contractor toconstruct test fills, formally submit material specifications andshop drawings, and construction procedures for the Engineer’sapproval.




Pima County argues that(vii) the “CQA Plan omitsrequirements fordocumentation and loggingrelated to a ‘photographicrecord of construction;’


Section 10 of the CQA Plan states “The CQA SiteSuperintendent will maintain, at the job site, a complete file ofDrawings and Technical Specifications, the CQA Plan,checklists, standard test procedures, daily logs, and otherpertinent documents.” A photographic record of the constructionwould be considered a “pertinent document” and would beupdated by the CQA personnel on a daily basis over the courseof the construction.

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




Pima County argues that(viii) the record of

construction qualityassurance activities isincomplete;”


Section 10 of the CQA Plan states “The CQA Consultant willensure that all quality assurance requirements have beenaddressed and satisfied.” This includes all requirements in theCQA Plan and the Technical Specifications for allinstalled/constructed items in the Construction Plans (not justthe geomembrane). The CQA Plan also addresses CQAprocedures for earthworks, pipework, concrete, and associatedappurtenant items. The procedures include verification ofmaterial specifications, sampling and testing of materials atspecified frequencies, remedial actions, and documentation ofthe construction and CQA results. Additionally, the technicalspecifications state that “All materials utilized are subject toapproval by the Engineer” and requires the contractor toconstruct test fills, formally submit material specifications andshop drawings, and construction procedures for the Engineer’sapproval.




Pima County argues that(ix) the list of recorddrawings fails to include allcritical elements of BADCTconstruction for the HeapLeach Facility;”

(ix) the list of recorddrawings fails to include allcritical elements of BADCTconstruction for the HeapLeach Facility;”

Attachment F,Items #13 & 14

Although not explicitly stated in the CQA Plan, the recorddrawings would be expected to include all elements of theconstruction of the heap leach and associated facilities includingthe raffinate, PLS and stormwater ponds and all pertinentcomponents and phases of construction.

Although not explicitly stated in the CQA Plan, the recorddrawings would be expected to include a complete constructionphotographic record.

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Meyer Revised Power Point - Maryland Office of ... · recommendations in ASTM D 6102 “Standard...

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