Download JETTY Preliminary Design Report...
Preliminary Jetty Design Doris North Project, Hope Bay Nunavut, Canada
Prepared for: Miramar Hope Bay Limited Suite 300, 889 Harbourside Drive North Vancouver, BC V7P 3S1 Canada
Prepared by:
SRK Project No. 1CM014.006
October 2005
Preliminary Jetty Design, Doris North Project Hope Bay, Nunavut, Canada Miramar Hope Bay Limited Suite 300, 889 Harbourside Drive North Vancouver, BC V7P 3S1
SRK Consulting (Canada) Inc. Suite 800, 1066 West Hastings Street Vancouver, B.C. V6E 3X2
Tel: 604.681.4196 Fax: 604.687.5532 E-mail:
[email protected] Web site: www.srk.com
SRK Project Number 1CM014.006
October 2005
Author Maritz Rykaart, Ph.D., P.Eng. Senior Engineer
Reviewed by Cam Scott, P.Eng. Principal
SRK Consulting Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada
Page 1
Table of Contents 1 Introduction .................................................................................................................. 1 1.1 Background ......................................................................................................................... 1 1.2 Scope of Work..................................................................................................................... 1 1.3 Report Organization ............................................................................................................ 1
2 Sealift Off-Loading Alternatives ................................................................................. 3 2.1 Introduction ......................................................................................................................... 3 2.2 Sealift Types ....................................................................................................................... 3 2.2.1 2.2.2
Deep Draft Vessels (Cargo Ships) ..........................................................................................3 Shallow Draft Barges...............................................................................................................4
2.3 Alternative Barge Off-Loading Locations ............................................................................ 5 2.3.1 2.3.2 2.3.3 2.3.4
Existing Barge Landing Site ....................................................................................................5 Roberts Bay Deep Water Port Site .........................................................................................5 East Shore Peninsula (Jetty Site #2) ......................................................................................6 Southern Roberts Bay Shoreline Site (Jetty Site #1 - Preferred Location) .............................7
3 Investigations............................................................................................................... 8 3.1 3.2 3.3 3.4 3.5
Introduction ......................................................................................................................... 8 Barge Access ...................................................................................................................... 8 Bathymetry .......................................................................................................................... 8 Shoreline Erosion Processes .............................................................................................. 9 Geotechnical Foundation Conditions .................................................................................. 9 3.5.1 3.5.2 3.5.3
EBA (1997) Roberts Bay Port Site Geotechnical Investigation...............................................9 Jetty Foundation Drilling (SRK Phase I Investigation) ..........................................................10 In-Situ Vane Shear Testing (SRK Phase II Investigation).....................................................11
4 Conceptual Design Alternatives ............................................................................... 12 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8
Introduction ....................................................................................................................... 12 Option 1: Continuous Rock Fill Jetty ................................................................................. 12 Option 2: Rock Fill Jetty with Arch Culverts ...................................................................... 13 Option 3: Rock Fill Buttressed Jetty with Prefabricated Decks ......................................... 13 Option 4: Conventional Piled Jetty with Prefabricated Decks ........................................... 14 Option 5: Cellular Sheet Pile Jetty .................................................................................... 14 Option 6: Rock Fill Jetty on In-Situ Frozen Ground........................................................... 15 Option 7: Bay Dredging & Rock Fill Jetty .......................................................................... 15
5 Preferred Design ........................................................................................................ 17 5.1 5.2 5.3 5.4 5.5 5.6 5.7
Selection of Preferred Design ........................................................................................... 17 Design Criteria .................................................................................................................. 17 Design Detail..................................................................................................................... 19 Optimization Opportunities................................................................................................ 19 Construction ...................................................................................................................... 20 Maintenance...................................................................................................................... 21 Decommissioning.............................................................................................................. 21
6 References.................................................................................................................. 23
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SRK Consulting Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada
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List of Tables Table 1: Summary of Jetty Design Criteria..................................................................................... 18
List of Figures Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6: Figure 7: Figure 8: Figure 9: Figure 10: Figure 11: Figure 12: Figure 13: Figure 14: Figure 15: Figure 16: Figure 17: Figure 18: Figure 19: Figure 20: Figure 21: Figure 22: Figure 23:
Site Map Sealift Off-Loading Alternative Locations Roberts Bay Bathymetry (per Frontier Geosciences Inc.) Preferred Jetty Location Plan In-Situ Vane Shear Testing and Drill Hole Locations Inferred Jetty Centerline Profile Option 1: Continuous Rock Fill Jetty – Plan Option 1: Continuous Rock Fill Jetty – Section Option 2: Rock Fill Jetty with Arch Culverts – Plan Option 2: Rock Fill Jetty with Arch Culverts – Section Option 3: Rock Fill Buttressed Jetty with Prefabricated Decks – Plan Option 3: Rock Fill Buttressed Jetty with Prefabricated Decks – Section Option 4: Conventional Piled Jetty with Prefabricated Decks – Plan Option 4: Conventional Piled Jetty with Prefabricated Decks – Section Option 5: Cellular Sheet Pile Jetty – Plan Option 5: Cellular Sheet Pile Jetty – Section Option 7: Bay Dredging & Rock Fill Jetty – Plan Option 7: Bay Dredging & Rock Fill Jetty – Section Typical Plan of Continuous Rock Fill Jetty Typical Section of Continuous Rock Fill Jetty (Section A-A’) Typical Section of Continuous Rock Fill Jetty (Section B-B’) Typical Plan for Possible Optimized Jetty Typical Section for Possible Optimised Jetty
List of Appendixes Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G
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MHBL Technical Memorandum Roberts Bay Bathymetry Report (Frontier Geosciences Inc. 2003) Summary of Roberts Bay Geotechnical Properties Phase I Foundation Investigation (SRK 2004) Phase II Foundation Investigation (SRK 2005) Technical Memorandum Outlining Preliminary Jetty Design Calculations Typical Geogrid Specifications
PreliminaryJettyDesign.Report.1CM014 006.emr.20051001_FINAL-Oct21.2005.doc, Oct. 21, 05, 2:26 PM
October 2005
SRK Consulting Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada
1
Introduction
1.1
Background
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Miramar Hope Bay limited (MHBL) is the planning on developing a small gold mine on the Arctic coastline in the Hope Bay Belt, Nunavut, Canada. This project, the Doris North Project is situated approximately 4 km inland from Roberts Bay, is remote and all equipment and supplies can only be economically transported to site via annual sealift during a short open water season in the late summer. Details of the project are documented in SRK (2005a), and stipulate the need for a sealift off-loading facility (jetty) in Roberts Bay (Figure 1). This report outlines preliminary engineering that has been completed in support of the jetty.
1.2
Scope of Work The jetty design presented in the Preliminary Surface Infrastructure Design Report for the Doris North Project, SRK (2005a) was selected based on baseline data and engineering investigations since 1997. The bulk of the engineering work has been completed by SRK Consulting (Canada) Inc. (SRK) on behalf of MHBL from 2002 onwards. Significant portions of this later work have never been formally documented. MHBL subsequently contracted SRK to document all background data feeding into the design of a jetty in a single report. The report would culminate in the selection of a jetty alternative, complete with preliminary design details. The report therefore contains the following information; •
Review of alternative sealift options;
•
Summary discussion of all relevant baseline and geotechnical data;
•
Review of alternative jetty designs;
•
Complete preliminary design for the preferred jetty alternative.
This report is furthermore intended to provide the information necessary to satisfy additional information requests and technical concerns raised during the conformity review process and Technical Meetings held for the Project in Yellowknife in August 2005.
1.3
Report Organization Section 2 of this report presents a discussion of the alternative sealift options that MHBL had considered for the Doris North Project. These alternatives consist of shallow draft barges mobilised from Hay River, Northwest Territories (NT), versus deep draft cargo ships mobilized from Montreal, Quebec.
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MHBL has initiated a series of technical studies to collect baseline and engineering data pertaining to the design of a jetty at Roberts Bay. This data is summarized in Section 3 of this report, and in most cases, detailed supporting documentation referred to in this section has been included as Appendices. Seven different alternative jetty designs have been proposed for the Doris North Project. Section 4 of this report describes these alternatives, and explains why a continuous rock fill jetty has been selected as the preferred alternative. Section 5 concludes with details of the preliminary design of a continuous rock fill jetty for the Doris North Project. These details include design criteria, construction procedures and reclamation plans.
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PreliminaryJettyDesign.Report.1CM014 006.emr.20051001_FINAL-Oct21.2005.doc, Oct. 21, 05, 2:26 PM
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SRK Consulting Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada
2
Sealift Off-Loading Alternatives
2.1
Introduction
Page 3
This section of the report summarizes the sealift alternatives that were considered for the Doris North Project. The first factor that MHBL had to consider was the type of sealift that would be used, and the second was the preferred jetty location.
2.2
Sealift Types
2.2.1 Deep Draft Vessels (Cargo Ships) Deep draft vessels (standard cargo ships) cruise annually into the Arctic to service various communities and industry. Canadian registered vessels are staged out of Montreal, Quebec, and travel down the St. Lawrence River, around the eastern coastline into the Arctic. These ships vary in size and can hold anything from 9 million to 50 million tonnes of fuel and deck cargo and carry their own barges onto which goods are reloaded for transfer to land. The open water season for ships into Roberts Bay is usually a four to eight week period between August and September. The ships can travel significantly faster than barges, and the shipping time between Montreal and Roberts Bay would generally be less than four weeks. Assuming arrival in Roberts Bay by the last week in August implies that MHBL would have to have their supplies ready for shipping in Montreal by the end of July. Montreal is a major international shipping port and most supplies and fuel can be sourced locally at competitive prices, with very little order and delivery lead time. This offers MHBL opportunities for saving, as well as further reducing the annual order lead time for re-supply. The per tonne shipping rate for supplies and fuel on these large ships are significantly less than for the barges (see Section 2.2.2), provided MHBL secures the entire cargo load for the ship. The annual re-supply volumes that MHBL envisage, will, however not come close to the ship cargo capacity, and as such the cost benefit is lost. The ships offload their cargo onto the barges with cranes. These cranes have a 13 tonne maximum capacity, and although this would be acceptable for normal operating re-supply, this restriction would preclude transportation of the construction equipment, and mill modules. In summary, even though the increased procurement time, and better fuel price is advantageous to MHBL, these savings are weaned away as a result of MHBL not being able to take full advantage of the large cargo capacity of the ships. Furthermore, the crane capacity effectively precludes the use of ships for the initial two shipping seasons. This was therefore eliminated as a viable sealift alternative for the Doris North Project.
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2.2.2 Shallow Draft Barges The most common form of sealift in the Canadian Arctic, especially the western and central Arctic is shallow draft barges staged from Hay River, NT. These barge trains are pulled by tugs. There is not a lot of choice when it comes to the selection of a shipping company, with the Northern Transportation Company Limited (NTCL) being the only company operating barges (www.ntcl.com). In order to take advantage of the short open water season, the fully loaded barges have to leave Hay River by early July every year. Off-loading of goods is done on a loose schedule which depends to a large extent of weather and ice conditions. Also, since barges often contain goods destined for more than one location, offloading is staged. MHBL currently uses barges for the re-supply of their exploration activities in the Hope Bay Belt. On average the barges arrive in Roberts Bay by the second to third week of August. In order to meet this deadline, the barge shipping company usually requires all goods to be in Hay River by the end of June. That means that the average delivery time for goods to site, excluding delivery time to Hay River, is at least eight weeks. Hay River is a large re-supply depot for the Arctic, but compared to Montreal, it is expensive and time consuming to get supplies and fuel to Hay River. The biggest barge currently in use is the NT 1500 Series, with a fully loaded capacity of 2,190 tonnes. There are future plans to put a new NT 2000 Series barge in production. This barge will increase the cargo capacity by almost a factor of two. With the aid of skilled tug skippers, the barges are highly manoeuvrable, and can be used in extremely shallow water. Often the barges are simply rammed onto the shoreline with the tugs with no need for offshore structures. MHBL opted to continue using the barge and tug alternative for the annual sealift for the Doris North Project. Although the barges are more expensive per tonne of transported goods when compared with a fully laden ship out of Montreal, the annual re-supply tonnage for the Project is not sufficient to fill up the ships, and therefore MHBL cannot benefit from reduced shipping rates. Furthermore, since there is no natural deep water dock to offload directly from a ship, all goods will have to be reloaded to barges before it can be moved closer to shore for final offloading. The offloading facilities that MHBL would have to construct would therefore be the same irrespective of which sealift option is selected.
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SRK Consulting Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada
2.3
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Alternative Barge Off-Loading Locations
2.3.1 Existing Barge Landing Site MHBL brings in an annual sealift to re-supply their exploration activities in the Hope Bay Belt. This sealift is via barges from NTCL staged out of Hay River. There are no permanent barge off-loading facilities in Roberts Bay. The barges are offloaded by pushing them directly onto a gravel beach located on the south western shore of the Bay (Figure 2). This gravel beach and the surrounding soils are permafrost of marine origin, and based on aerial photography and other regional geotechnical investigations and thermal monitoring (EBA 1997; SRK 2005a, b) the soils are likely to be ice-rich. The beach itself measures approximately 30 x 30 m and provides a stable off-loading platform for the barges. The benefits of continuous use of this site for the duration of the Doris North Project are clear. It is located on the western side of the Bay, which is well protected from the prevailing winds and it may not require the construction of a permanent off loading facility. In the event that the practice of beaching the barges is considered to pose potential significant environmental effects, a dock (jetty) could be constructed offshore; however, this structure would be relatively modest in size. Therefore, to make this site functional as a permanent off-loading facility a dock (jetty) would have to be constructed to protect the beach and an off loading area away from the beach on a permanent pad would be required. This site is approximately 6 km from the camp/mill site (SRK 2005a), requiring an additional 1.5 km of permanent all-weather road, including a major stream crossing. Alternatively equipment can be off-loaded, secured and transported via winter road. Based on all of these factors, MHBL decided not to pursue the use of this site as a permanent jetty location for the Doris North Project.
2.3.2 Roberts Bay Deep Water Port Site Historic site development studies (EBA 1997) within the Hope Bay belt identified a preferred deep water sea terminal location on the west side of Roberts Bay (Figure 2). At that time the concept was to use deep water ships for the annual sealift, and to transfer goods to barges for offloading at the terminal. The proposed port site is located in waters reaching 50 m depth with basalt rock outcrop on the west shore serving as terminal facility area. Bathymetry data from a local hydrographic survey showed that the sea bottom drops off steeply toward the east, reaching 35 m depth within 100 m offshore. The basalt outcrop is surrounded by permafrost marine-derived sediments on the west side. Based on field investigations carried out in 1997 it was concluded that a balanced bedrock cut and fill would be required to grade the site by removing the top of the bedrock outcrop and filling the
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marine lowland. This will create a portion of the site where support structures for the dock could be founded. Two options for barge berthing were considered; (a) a steel sheetpile cellular structure and (b) a floating transition ramp using either a pontoon or small barge moored at the shore side. The sheetpile cellular structure would require driving piles into bedrock (approximately 16 m below mean sea level) and replacing all internal clay sediment with rock fill. The floating transition ramp would require the construction of a fill structure to form an abutment in the shallow water. This fill structure would consist of engineered fill placed in layers to the desired final grade. This site has the distinct advantage of deep water, and since it is on the west shore of Roberts Bay, adjacent to a steep cliff, it is well sheltered from the prevailing winds. It was however excluded as a preferred alternative for the Doris North Project, primarily due to its distance from the camp/mill site (approximately 9 km). The use of this site would required an additional 5 km of permanent allweather road, and a major stream crossing, or alternatively summer storage with winter transport via a winter road.
2.3.3 East Shore Peninsula (Jetty Site #2) Detailed bathymetry in Roberts Bay (see Section 3.2) suggests that there is a section of deep water immediately west of the peninsula jutting 700 m out into the Bay south of the main island (Figures 2 and 3). Barges could enter this section of the bay from west of the island and berth up to a 30 to 50 m long jetty. Offshore geotechnical conditions were not evaluated in this zone, but from aerial photography and regional data (EBA 1997; SRK 2005a, b) the soil lithology is probably soft marine sediments overlying intact competent bedrock. The onshore terminus of this jetty would be on bedrock outcrop, which covers most of the peninsula. Although the creation of road access through the bedrock peninsula would require significant drilling and blasting, it would likely be cost effective, since the development of the project requires substantial volumes of quarried material. The site was however not selected as a preferred alternative due to concerns about potential significant adverse environmental effects on aquatic life, specifically migrating Arctic Char which are known to spawn in Little Roberts Creek. MHBL was of the opinion that the narrow channel between the peninsula and island could cause conflict in the event that Char was moving towards the spawning area. It should be noted that no specific studies were conducted to confirm if a jetty in this location would impact the Char; however, MHBL opted to err on the safe side.
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2.3.4 Southern Roberts Bay Shoreline Site (Jetty Site #1 - Preferred Location) The Bay bathymetry (see Section 3.2) indicated a section of deeper water leading up to the shallow shelf along the southern shoreline of Roberts Bay (Figures 2 and 3). This location suggested that constructing a 100 m long jetty would allow for the safe offloading of barges. Shoreline geotechnical investigations (SRK 2005a) have confirmed the presence of ice-rich marine silt and clay permafrost between patches of exposed bedrock. In order to allow the use of this site, an all-weather road will have to lead from the jetty towards a lay-down area approximately 100 m inland from the shoreline (a self-imposed restriction set by MHBL). Offshore geotechnical investigations (see Section 3.4) confirmed that the jetty will have to be constructed on deep soft marine sediments overlying bedrock, in shallow water. Based on the evaluation of all the other alternative jetty locations, this site was selected as the preferred sealift offloading site for the Doris North Project. Although it is recognised that an approximately 100 m long jetty would have to be constructed on challenging foundation conditions, the proximity of the site to the camp/mill is advantageous and offers potential for cost saving. There are also no potential significant environmental effects associated with constructing the jetty at this location (see Section 3.4).
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SRK Consulting Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada
3
Investigations
3.1
Introduction
Page 8
MHBL initiated a number of technical studies to obtain baseline data that can be used to design a jetty for the Doris North Project. These studies included confirming the feasibility of barges accessing the site, providing adequate bathymetry, evaluating potential shoreline processes, wind and wave heights etc., as well as confirming the jetty foundation conditions.
3.2
Barge Access MHBL consulted with directly with NTCL on the feasibility of using the preferred jetty location as an offloading facility. A representative from NTCL personally inspected the site, reviewed orthophotos, conducted an aerial reconnaissance of the site via helicopter, carried out a cursory bathymetric reconnaissance via small boat, and finally manoeuvred a tug into the area under consideration. The findings of this consultation were documented in a Technical Memorandum (included as Appendix A) by MHBL, and confirmed that the site would be suitable as an offloading facility as seen from the perspective of the shipping company.
3.3
Bathymetry Frontier Geosciences Inc. carried out an over water bathymetric survey at the southern extremity of Roberts Bay in September 2003 (Frontier Geosciences 2003, also included as Appendix B). The survey was completed with a marine depth sounder as recorded from a small boat. The depth sounder data was correlated with a GPS to accurately locate each data point. The bathymetry (Figure 3) indicated the presence of an elongate, north-south trending channel defined generally by the 5 m water depth contour in the south, and water depths in excess of 30 m in the north. The channel was found to be relatively wide; however, at the southernmost point it narrows to approximately 150 m. A localized deeper water depression was also observed in the middle of the survey area and west of the main island in the northeast segment of the area. The area is bounded to the north, by a region of relatively shallow depths. In the area of the jetty, water depths are shallow, in the order of 1 m, with a relatively steep drop off to 5 m depth at around 75 to 100 m offshore. Limited boat draft and boulder hazards in this shallow shelf precluded more detailed coverage of this area. Subsequent to this bathymetric survey, SRK conducted a series of geotechnical investigations in the jetty location (Section 3.5). Measurements of water depth at the proposed jetty terminus by SRK engineers suggest that the water is shallower by approximately 1 m, than proposed by the
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bathymetric survey by Frontier Geosciences. Should the measurements by SRK be accurate, it may offer optimization opportunities for the jetty construction, and therefore MHBL proposes to carry out an additional detailed bathymetric survey of the jetty location prior to proceeding with detailed design of the jetty (see also Section 5.4).
3.4
Shoreline Erosion Processes A number of field investigations were completed by Golder Associates Ltd. (Golder) during the summer of 2004 to allow characterization of shoreline processes in Roberts Bay in the vicinity of the jetty (Golder 2005). These studies were an expansion of scoping level studies that were originally completed in June 2004 (Golder 2004). The field programmes included; (1) collection of wave height data, (2) collection of tidal data, (3) measurement of tidal currents, (4) characterization of shoreline substrate, and (5) wind measurement. Using a numerical model, calibrated with the field data, it was concluded that the largest and most frequent waves at the jetty site come from the north, and the maximum waves are predicted to be 0.9 m in height. The predominant force on long-shore transport of sediment in the foreshore zone of Roberts Bay was estimated to be wind waves during the short summer open water season. The net transport of sediment is north to south along the west side of the Roberts Bay shoreline, and the area proposed for the jetty appears to be an area of low to zero long-shore transport. Overall there is minimal material available for sediment transport in Roberts Bay. Cobbles and boulders characterize much of the shoreline, which are not transportable by the local waves. The bed of Roberts Bay, including shallow near shore areas, is comprised of marine clay. These clays appear to be mobilized during storm events, with subsequent deposition during calm periods. It was concluded that sediment transport is an episodic process, with most transport occurring during summer months from the north. The mean wind speeds in the area are also too low to generate appreciable sediment transport. Therefore, it was concluded that the presence of the jetty is not anticipated to cause significant potential adverse environmental effects on near- or long shore marine processes resulting in localized changes in sediment transport and deposition patterns.
3.5
Geotechnical Foundation Conditions
3.5.1 EBA (1997) Roberts Bay Port Site Geotechnical Investigation EBA Engineering Consultants Inc. (EBA) carried out a geotechnical investigation in May 1997 (EBA 1997) to characterize onshore and offshore foundation conditions to develop preliminary
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designs for a deep water dock along the western shore of Roberts Bay (see Figure 2 and Section 2.3.2 above). The program consisted of six onshore geotechnical drill holes, four offshore geotechnical drill holes, eight offshore probe holes and 11 bathymetric check points. The onshore drill holes were completed in order to obtain geotechnical and permafrost data for preliminary design of foundation conditions for terminal facilities. Three 15 m thermistor strings were installed in three separate boreholes to provide ground temperature data. The four offshore geotechnical drill holes provided lithology and soil samples of the ground conditions in an area where a sheet pile structure was considered to provide barge berth. The eight offshore probe holes provided data on the depth to seabed, depth to bedrock and lithology of the marine sediments for potential ship anchoring and mooring locations. The bathymetric check points provided depth to seabed along three lines extending east from the shoreline. The onshore soils were found to be consistent with that observed during other later drilling programs (SRK 2005a). The soils are of marine origin and generally consist of a thin layer of organic peat overlying up to 5 m of silty clay of low plasticity with occasional sand laminae. A thin layer of sand and gravel underlies the silty clay and this rests on intact competent volcanic rock identified as basalt and rhyolite. Soil ice content was low to moderate. Soil pore water was saline, and although measured salinities indicated values greater than the salinity of seawater, the report concludes that the results may have been compromised by the brine used in the drilling fluid. The offshore drill holes close to shore indicated a soil lithology consisting of silty clay of variable thickness (2 to 8 m) overlying competent bedrock of the same origin as onshore. In one hole a sand layer was found to underlie the silty clay. Laboratory measurements confirmed that the sediments have an undrained shear strength between 2 and 22 kPa, is very soft and compressible, with low plasticity. Further offshore where water depths exceeded 50 m the lithology remains similar; however, the silty clay thickness increases to between 6 and 14 m. Although these investigations are located a significant distance from the proposed jetty location (Figure 2), the general similarity of soil lithology that has been observed throughout the site (SRK 2005a, b) suggest that this data will be a useful indicator to support site specific jetty foundation data. Appendix C contains a summary of the pertinent geotechnical data on submarine sediments as extracted from these drill holes.
3.5.2 Jetty Foundation Drilling (SRK Phase I Investigation) SRK completed a reconnaissance level geotechnical investigation in April 2004 (Appendix D) at the proposed jetty location (Figure 4). The intent of the drill program was to determine site specific information pertaining to the proposed alignment of the jetty.
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Four drill holes were completed along the proposed centerline of the jetty (Figure 5), spaced approximately 25 m apart, extending out from the shoreline, to a maximum distance of approximately 100 m. The investigation confirmed that the water depth at the jetty location varies between 0 to 5 m (Figure 6). Sea ice approximately 2 m thick develops in the winter and freezes to the bottom of the seabed for at least the first 55 m of the proposed approximately 100 m long jetty. The drilling results confirm sub-ocean permafrost to at least this location. For the first 55 to 75 m from the shoreline, the jetty foundation consists of a 3 to 5 m thick layer of frozen marine silt and clay over 6 to 9 m of sand and gravel. The remainder of the jetty has deeper water and is underlain by unfrozen marine silt and clay, 8 to 12 m thick. The underlying basalt bedrock is intact and competent. Appendix C contains a summary of this data.
3.5.3 In-Situ Vane Shear Testing (SRK Phase II Investigation) A second phase geotechnical foundation investigation to specifically measure the in-situ shear strength of the soft marine sediments at the proposed jetty location was conducted by SRK in April 2005 (Appendix E). The testing consisted of six borings approximately 5 m deep using a Nilcon vane-shear apparatus. The six borings were all located at the terminus of the jetty where the proposed fill would be the maximum (Figure 5), and where drilling data has confirmed the sediment layer to be the thickest and thus potentially the most sensitive to excessive loading. At each boring location, vane shear tests were taken at 5 or 6 depths to determine a depth profile of shear strength. Shear testing in these deeper marine sediments approximately 90 to 100 m from the shore confirmed that the upper 5 m of the marine sediments have peak shear strengths ranging between 14 and 28 kPa, with an average value of 21 kPa. Residual strengths ranged between 5 and 13 kPa with an average value of 9 kPa. Generally the strength was observed to increase with depth.
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PreliminaryJettyDesign.Report.1CM014 006.emr.20051001_FINAL-Oct21.2005.doc, Oct. 21, 05, 2:26 PM
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SRK Consulting Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada
4
Conceptual Design Alternatives
4.1
Introduction
Page 12
A number of alternative jetty designs were evaluated for the Doris North Project. Brief details of the conceptual alternatives are discussed in the following sections of this report. These alternatives were developed with the assistance and guidance of Westmar Consultants Inc. (Westmar), an engineering firm specializing in the design and construction of offshore infrastructure including large ports, docks and jetties.
4.2
Option 1: Continuous Rock Fill Jetty The shallow water depths leading to the terminus of the jetty, suggest that a simple continuous rock fill jetty, 1 to 3 m thick would be a practical design alternative (Figures 7 and 8). The soft unfrozen marine sediments approximately 50 to 100 m offshore has low bearing capacity, and therefore special construction considerations have to be considered. Pre-loading would be one method of overcoming the bearing capacity problem. This would be done by initially placing approximately half the fill thickness, after which some time for settlement is allowed. Placement of the remainder of the fill would follow at an appropriate time. Pre-loading could be done over a few summer construction seasons, or alternatively the first fill could be placed in the winter (through the sea ice), with the final fill following six months later during the open water season. The bearing capacity concerns can also be overcome by constructing the fill in layers, with each layer supported by geosynthetics (i.e. geogrids and geotextiles). These geosynthetics does not per se increase the bearing capacity, but prevents the pad from spreading laterally, as well as precluding the other possible failure mechanisms of a pad constructed on low strength ground. This technique of reinforcing pads is commonly used, as documented in Koerner (2005). Spreading construction of the jetty over a number of seasons, in order to allow for preloading of the foundation would not be an acceptable approach to MHBL, and would result in the exclusion of this design alternative, since the proposed MHBL construction and production schedule for the Doris North Project would be compromised; however, preloading during the winter, with the remainder of the fill being placed during the immediately following summer, would be an acceptable approach. Notwithstanding the possibility of preloading, the inclusion of geosynthetics in the design would be paramount to its acceptance, since that would ensure constructability. It is however likely, that even with the inclusion of geosynthetics, the jetty will undergo differential settlement and annual maintenance of the jetty will be required. Preliminary cost estimates for this design alternative suggest, that construction would be less than $0.3 million. This cost is considered to be all inclusive, since construction can be carried out with a conventional construction fleet, by a suitably qualified and experienced earthworks contractor.
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Option 2: Rock Fill Jetty with Arch Culverts Prior to completion of the Golder (2005) shoreline processes study, one of the potential adverse environmental effects associated with the continuous rock fill jetty (Option 1) was that the presence of an impassable object jutting out 100 m from the shoreline may impede the passage of fish, and that it may effect near- and long-shore erosion processes. In order to partially mitigate against this potential adverse effect, a modified continuous rock fill jetty was presented which includes a series of large diameter steel culverts (Figures 9 and 10). In concept these culverts should achieve the goal of allowing fish to pass through the jetty; however, the feasibility of keeping these culverts operational as differential settlement takes place may be problematic. The cost of including the culverts would not be significantly more than for the continuous rock fill jetty; however, the cost of maintenance would be substantially increased if culverts had to be replaced over time. Due to the marginal benefits that the culverts offer, the increased maintenance risk, and the fact that the presence of a rock fill jetty has been shown to not have any potential adverse environmental effect, this jetty design alternative was not given further consideration.
4.4
Option 3: Rock Fill Buttressed Jetty with Prefabricated Decks In an attempt to minimize the amount of rock fill required, and to reduce the jetty footprint an alternative design was considered which entailed construction of rock fill islands or buttresses. These buttresses would be linked with prefabricated steel bridge decks or possibly pre-cast concrete decks (Figures 11 and 12). Summer construction of this type of design would require specialized working barges, which would be cost prohibitive. Alternatively, winter construction would have to be carried out through the sea ice, which would once again pose significant challenges to ensure ice-free working conditions. Preliminary cost estimates suggest that this type of structure (under winter construction conditions) would be approximately twice as expensive as a continuous rock fill jetty. This cost however has significant uncertainties associated with potential technical complications which may substantially increase the cost. Finally, concerns with differential settlement of the buttresses and the associated deformation of the bridge deck or pre-cast slabs, has resulted in the exclusion of this as a viable alternative jetty design.
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Option 4: Conventional Piled Jetty with Prefabricated Decks An alternative jetty design to Option 3, which keeps the benefits of a reduced footprint but mitigate against the potential instability of the rock fill buttresses, would be to support the prefabricated bridge decks or pre-cast concrete slabs with piled foundations (Figures 13 and 14). Pile supported wharf structures have been successfully used in Arctic conditions. Generally the arrangement would consist of steel pipe piles, cast in-place concrete pile caps and the prefabricated steel bridge deck or pre-cast concrete slab on top. The pile supported structure will be subject to berthing loads from the barges, as well as significant sea ice pressures. Consequently, the piles will require socketing into the bedrock, and possible protection through placement of a rock fill shell around each pile. Rock socketing increases the cost of the structure, due to the need for specialized equipment, and the increased effort also substantially increases the construction time. Preliminary cost estimates suggest that this jetty design alternative would be in excess of $2 million, excluding the cost of shipping specialized pile driving equipment to site. This jetty design alternative was subsequently excluded from further consideration.
4.6
Option 5: Cellular Sheet Pile Jetty A sheet pile cell is a gravity type structure capable of withstanding high lateral loads from vessel or ice impact without sustaining damage. A jetty design which includes the use of two 23 m diameter sheet pile cells is presented in Figures 15 and 16. These cells would be placed on the soft marine sediments approximately 50 to 100 m offshore to mitigate against the differential settlement that a continuous rock fill jetty (Option 1) would be subjected to. These sheet pile cells would be linked to the shoreline with a 40 m long continuous rock fill jetty which is founded on permafrost. The sheet pile cells would have to be founded in bedrock, and the soft marine sediments within them would have to be replaced by rock fill. This would require the use of specialized equipment, and if permafrost is encountered, the sheet pile cells may not even penetrate the substrate. Preliminary cost estimates for this jetty design were estimated at $7.4 million, excluding (1) transportation of specialized equipment and supplies from Hay River, NT to Roberts Bay, (2) cost of rock fill, and (3) fuel for construction equipment. An optimization was considered to the design whereby only a single sheet pile cell was to be used; however the cost of this alternative still came in at approximately $5 million. Based on the cost of this design, it has been excluded as a viable alternative.
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Option 6: Rock Fill Jetty on In-Situ Frozen Ground The presence of submarine permafrost along a portion of the jetty alignment suggest that possibly the entire jetty foundation could be artificially frozen, to provide a stable foundation that would preclude differential settlement. The layout would consist of placing a continuous rock fill jetty (similar to Option 1) on the frozen seabed. In advance of placement of the rock fill, the silt and clay stratum within the footprint of the jetty would be frozen using mechanical refrigeration. Mechanical refrigeration of this stratum would be achieved by installing a network of thermosyphons below the seabed using directional drilling techniques. The thermosyphons would then be connected to a refrigeration plant system which provides the means to freeze the soil. Based on discussions with a ground-freezing contractor, installation of the thermosyphons would begin in the spring (May), with completion in the summer (July). Upon completion of the refrigeration system, it has been estimated that the silt and clay stratum would require 12 months in order to completely freeze. Consequently, placement of rock fill on the frozen seabed to form the jetty cannot begin until one year after the refrigeration system has been operational. Based on this schedule, the jetty would be ready for service two years following the start of ground freezing. An order of magnitude cost estimate has been provided by a ground freezing contractor (Arctic Foundations of Canada Inc.) The supply and installation of the refrigeration system is estimated at $2.5 million and excludes (1) the supply of power to the refrigeration plants, (2) transportation of equipment from Hay River, NT to Roberts Bay, and (3) the cost of rock fill. Based on the cost of installing the ground freezing system and the prolonged schedule to complete the jetty, ground freezing is not recommended at this site.
4.8
Option 7: Bay Dredging & Rock Fill Jetty At the site of the jetty, the inshore seabed grade is shallow. In order to achieve water depths sufficient for clearance of the loaded draft of the barges, an arrangement comprised of dredging the seabed towards shore and placing a small rock fill jetty to the edge of the dredge pocket has been investigated (Figures 17 and 18). The barges would be orientated longitudinal to the jetty in order to minimize dredge volume. The width of the dredge pocket would include an allowance on either side of the barge for a tug boat. The depth of the dredge pocket would provide an under keel clearance of 1 m for the loaded barge at lower low water level (LLWL). At the inshore side, below the footprint of the rock fill jetty, dredging would extend down to the sand and gravel layer to remove the silt and clay stratum. The dredged material would be side cast to locations within the vicinity of the site, subject to approval from regulatory authorities. This material may in fact have to be relocated to deep water, which would further increase costs.
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The jetty itself would comprise a continuous rock fill structure founded on permafrost, similar to the jetty described for Option 1. A preliminary cost estimate suggest that this design will cost approximately $1.9 million, excluding (1) transportation of equipment from Hay River, NT to Roberts Bay, (2) cost of rock fill, and (3) cost of fuel. Although no baseline data is available to confirm what the potential adverse environmental effects of dredging would be, it is conceivable that these effects may be significant, and that fact combined with the projected capital cost, resulted in the rejection of this alternative.
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Preferred Design
5.1
Selection of Preferred Design
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As discussed in Section 4 of this report, all of the proposed alternative jetty designs were judged to be inappropriate for the Doris North Project, with the exception of the continuous rock fill jetty (Option 1). The most significant technical issue associated with the continuous rock fill jetty is the low strength characteristics of the marine sediments, that will result in differential settlement of the jetty, and that may require the inclusion of geosynthetics to help support the structure. Notwithstanding the inclusion of the geosynthetics, and taking into account annual maintenance, the continuous rock fill jetty was deemed to be feasible, and preliminary cost estimates suggests that it would be economically justified for the Project. The presence of an approximately 100 m long continuous rock fill jetty in Roberts Bay will have a potential adverse environmental effect; however, shoreline process studies have confirmed that these effects will not be significant (Golder 2005). Therefore, the continuous rock fill jetty was selected as the preferred jetty design, and the following sections of this report documents the details of the proposed preliminary design.
5.2
Design Criteria Design criteria for the jetty are summarized in Table 1. It should be noted that the jetty will only be used for a period of two to three weeks during the late summer (August) every year that it is in operation. Furthermore, for the Doris North Project, the jetty is only expected to be used for a period of four years. This includes two years of mining and two years of active decommissioning. Subsequent to active decommissioning the jetty will no longer be required, since further annual resupply volumes are expected to be small and will be done via sealift to the existing barge landing site (see Section 2.3.1). MHBL therefore proposes to design the jetty with a minimal design life, and accept the risks and consequences that this design criteria has. The risks include damage to the jetty due to large waves, storm surges and sea ice. Furthermore, annual settlement and frost heave could result in damage to jetty. MHBL will however implement the necessary maintenance actions to ensure safe operation of the jetty when the time requires (see Section 5.6). The physical consequences of damage to the jetty include addition of construction rock and an increased jetty footprint. MHBL acknowledges these facts and have made allowance for these consequences (see Section 5.3). Operational consequences for these damages include delays to the offloading of the barges, with associated increased operational costs for the mine.
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Table 1: Summary of Jetty Design Criteria Design Component
Design Criteria Approximately 4 years (two years of mine life + two years of active mine closure; traditional barge landing and winter road, or winter airstrip will be used for the post closure phase)
Service Life
Barge NT 1500 Series: 1,886 tonne dead weight; 76.2 m LOA; 17.1 m Beam; 0.97 m minimum freeboard; 3.05 m Draft
Vessels
Barge NT 2000 Series (Future): 3,870 tonne dead weight; 90 m LOA; 18.9 m Beam; 1.10 m minimum freeboard; 2.90 m Draft Integrated Tool Carrier (TC-28) = 11,412 kg Wheel Loader Komatsu WA500-3; operating weight = 31,000 kg (Supplied by NTCL for off-loading only
Vehicles
(Provisions for unloading mill modules for the mine at the jetty have not been included; these modules will be offloaded at the existing barge landing site) Tide levels in Melville Sound (north of the site), as listed below, are taken from Canadian Hydro-graphic Service Chart 7780. EHWL and ELWL are based on tides at Cambridge Bay. Tides are referenced to local Chart datum. Extreme High Water Level (EHWL) = 0.5 m Higher High Water Level, Large Tide (HHWL) = 0.2 m Higher High Water Level, Mean Tide = 0.2 m Tides
Mean Water Level (MWL) = 0.0 m Lower Low Water Level, mean Tide = -0.1 m Lower Low Water Level, Large Tide (LLWL) = -0.1 m Extreme Low Water Level (ELWL) = -0.3 m This tide data is consistent with site specific data reported in Golder (2005) and Frontier Geosciences (2003). Minimum Water Depth: Established to provide a minimum of 0.5 m keel offset for the Series 1500 barge below LLWL.
Jetty Working Platform
Deck Height: Established to provide 1.0 m of freeboard above the HHWL.
Roadway Width
6m
Barge Ramp
Barges are supplied with a 25 ft long ramp to span between the barge and the jetty structure. The maximum recommended grade of the ramp is 6%. Considering the freeboard range of the barges (fully loaded to empty), a permanent ramp at the jetty may be required. This will not affect the overall jetty footprint and well be fully evaluated at the final design stage.
Jetty Terminus Work Area
NTCL requires only 6 m of work space to offload the barges; however, they prefer a berthing face of at least 20 m wide. Barge unloading can be from barges orientated laterally or longitudinally to the jetty.
Wave Conditions
Geotechnical Parameters
Largest waves from North, with maximum wave height = 0.9 m Maximum sustained storm surge = 1.0 m. Existing Seabed: Unfrozen and frozen Silt and Clay; Saturated unit weight = 18 kN/m3; Peak Shear Strength = 15 kPa 3
Existing Seabed: Frozen Sand and Gravel; Saturated unit weight = 18 kN/m Engineered Fill: Rock fill; Unit weight = 19.62 kN/m3 Bulk Fill, Sub Grade: Run-of-quarry rock (< 1,000 mm size fraction)
Engineered Fill
Transition Zone, Select Grade; Crushed and screened quarry rock (< 200 mm size fraction) Surfacing Grade; Crushed and screened quarry rock (< 38 mm size fraction)
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MHBL will be the only official user of the jetty. MHBL does however acknowledge that local communities may make use of the jetty whilst it is in operation. MHBL would not restrict access to the jetty unless, MHBL is of the opinion that the jetty is not safe to use. In such instances MHBL reserves the right to restrict access to the jetty.
5.3
Design Detail Design details for the jetty are provided in Figures 19 through 21. Appendix F contains details of the preliminary engineering design of the jetty. The total footprint of the jetty is estimated at approximately 1,800 m2 (this is the base footprint, i.e. the surface area covered by the pad). The total amount of rock fill is estimated at approximately 5,600 m3 (11,600 tonnes). For planning purposes, and arbitrary allowance of 50% increase of this footprint and rock fill volume has been made (i.e. increase in footprint of 900 m2 and volume of 2,800 m3). This allowance caters for unforeseen settlement and slumping. Discounting the required overlap, the surface area coverage of the primary geogrid layer (based on a single layer) is estimated at approximately 3,300 m2. This footprint exceeds the jetty footprint to ensure that all rock fill will be on the primary geogrid layer. Typical specifications of the geogrid are included as Appendix G.
5.4
Optimization Opportunities Based on a fully laden NT Series 1500 barge draft of 3.05 m, and measuring from the LLWL, with a keel offset of 0.5 m, the minimum water depth at the jetty terminus needs to be approximately 3.6 m. The proposed preliminary jetty design shows a minimum water depth at the jetty terminus of just over 5 m, which effectively allows for a keel offset of just under 1.3 m (based on the bathymetry measured by Frontier Geosciences, see Section 3.3). As discussed in Section 3.3, there is some uncertainty associated with the bathymetry data, and therefore the preliminary jetty design has been based on conservative assumptions. Prior to conducting the detailed jetty design, MHBL will carry out a detailed bathymetric survey of the jetty area. If in fact, there is sufficient water depth at the jetty terminus, as is suggested by the current bathymetric data, the jetty terminus will be moved closer inshore to coincide with a minimum water depth of 3.7 m. This will result in the total jetty length reducing to 60 m, with a subsequent reduction in footprint of 1,200 m2 and 50% less rock fill would be required (Figures 22 and 23). Under this scenario, the bulk of the jetty will be on more stable frozen marine sediments, and subsequently the construction and maintenance issues will be significantly improved. As discussed in Appendix F, the size of the jetty terminus directly impacts the pressure that the jetty exerts on its foundation. Prior to conducting the detailed jetty design, MHBL will conduct further foundation testing at the jetty terminus, to confirm the optimal size of the jetty terminus, since it may be beneficial to reduce its size. Such a reduction would however result in a smaller jetty footprint and a smaller amount of construction rock being used.
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Finally, a decision on the need to preload the jetty will be made after completion of further geotechnical testing at the jetty terminus. Since all the potential optimizations that will be considered at the detailed design stage will lead to a smaller jetty, with a reduced footprint and will require less construction rock, the preferred design tabled at this time is conservative and appropriate.
5.5
Construction Construction of the continuous rock fill jetty will be carried out during the summer open water season in Roberts Bay. Construction will be suspended for a two week period in late July to not interfere with large numbers of capelin that move through the area during migration to their spawning grounds. Construction will consist of end-dumping the engineered fill (quarry rock) from the shoreline towards the terminus of the jetty approximately 100 m offshore. After a few dump loads have been placed, a loader or dozer will be used to flatten the advancing front such that equipment can continue to end dump. In deeper water (more than 2 m depth) the initial rock fill be manually placed using an extended boom excavator. This will reduce the impact surcharge on the soft marine sediments and allow for more controlled placement of the fill. Prior to placing any rock fill, a series of geosynthetics (at least two layers of geogrid) will be placed on the seabed. These geogrids will extend at least 5 m beyond the outermost edge of the final jetty footprint and will be at least 5 m ahead of the current fill being placed. The geogrid overlap will not be less than 2 m. The placement of the geogrid will be done by Arctic divers. After completion of the bulk fill to the terminus of the jetty, the transition zone and jetty surfacing grade material will be placed once again moving from the shore advancing out towards the jetty terminus. At the outset of the construction season the entire perimeter of the jetty construction zone will be encircled by a silt curtain, to effectively mitigate against the release of suspended solids as material is dumped onto the soft marine sediments. As discussed previously, further geotechnical investigation in the jetty terminus area will confirm whether preloading of the jetty fill in areas that exceed 3 m in fill would be advantageous. If this is recommended, the first lift will be constructed during the winter, though the sea ice. The jetty will be constructed from clean rock located in Quarry #1 (Figure 1). This rock has been geochemically tested to confirm that there would be no adverse environmental effects associated with its use (AMEC 2003). The quarry rock will not be washed prior to placement. Since there will be some blast residue on this rock when it is placed in Roberts Bay, SRK modelled the water quality in the Bay to confirm that there would be no adverse environmental effects as a result of this practice. The results of this calculation are documented as an Appendix to SRK (2005c).
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5.6
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Maintenance It is expected that the jetty will continue to undergo differential settlement over its lifetime, although the rate of settlement will likely exponentially decrease as time progresses, consistent with consolidation theory. Considering the fact that the jetty will only be in use for two to three weeks in any year, this differential settlement can be managed with a program of annual maintenance. Annual maintenance will consist of adding rock fill to the jetty surface, such that the traffic grade would be passable for barge off-loading equipment. Furthermore, the design freeboard of 1 m above the HHWL would be maintained. For planning purposes it has been assumed that the jetty surface would require an additional 50 cm of rock fill every year during its life. This means 350 m3 of additional construction rock will be required every year for four years. During initial construction, a stockpile of additional crushed rock, specifically for jetty maintenance will be left in Quarry #1 (Figure 1). Every year this fill, as required, will be added to the jetty traffic surface by end-dumping and grading. If substantial fill is anticipated in deeper water, and there would be potential for large boulders to run down the side slopes and disturb sediments on the seabed, silt curtains will be deployed prior to undertaking any maintenance work. This will be to effectively mitigate against any possible increased turbidity in the Bay. The barge operator, NTCL, requires that MHBL carry out a bathymetric survey of the channel leading up to the jetty every year prior to barge arrival. MHBL will extend this bathymetric survey to include the jetty footprint, such that accurate records of the jetty can be kept. This data will furthermore provide data with respect to the potential effect of the jetty on shoreline processes.
5.7
Decommissioning The jetty will remain in operation for two years of active decommissioning after mining ceases. At that time all mooring hardware will be dismantled and removed from the jetty. The jetty will then be partially removed. Partial removal will entail lowering the jetty surface to 30 cm below LLWL. This will be achieved by pushing the excess material to either side of the jetty, without actually picking up and removing the material. This will result in an increase in the base footprint of the jetty. Complete removal is not possible without removal of a substantial volume of natural marine sediments. This is due to the fact that the jetty will continue to settle into the marine sediments over its lifetime. This preliminary jetty design is specifically for the two year Doris North Project. Should further exploration prove a larger project in the Hope Bay Belt, MHBL may decide to change the design of the jetty to accommodate a larger scale and longer duration project. Such a change will naturally result in a revised environmental review process; however, it should be noted that the jetty design as proposed in this report, may become the foundation of a larger scale jetty at this location.
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This report, “Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada”, has been prepared by SRK Consulting (Canada) Inc.
Prepared by:
Maritz Rykaart, Ph.D., P.Eng. Senior Engineer
Reviewed by:
Cam Scott, P.Eng. Principal
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References AMEC Earth & Environmental Ltd. 2003. ARD and Metal Leaching Characterization Studies in 2003, Doris North Project, November. EBA Engineering Consultants. 1997. Boston Gold Project Geotechnical Investigation Proposed Roberts Bay Port. Report Submitted to BHP World Minerals, October. Golder Associates Ltd., 2004. Supplementary Information on: Potential Impacts on Shorelines due to Construction of Jetty at Roberts Bay – Miramar Doris North Project. Golder Associates Ltd. Report No. 04-1373-002. Golder Associates Ltd., 2005. Potential impacts on shoreline due to construction of a jetty at Roberts Bay – Miramar Doris North Project. Golder Associates Ltd. Report No. 04-1373-009-4100: 29 p. + 6 app. Frontier Geosciences Inc., 2003. Report on Marine Bathymetry Survey, Proposed Roberts Bay Docking Facilities, Cambridge Bay Area, Nunavut. Report submitted to SRK Consulting, September 2003. Koerner, R.M., 2005. Designing with Geosynthetics, Fifth Edition. Pearson Prentice Hall, N.J., 796 p. SRK Consulting (Canada) Inc., 2005a. Preliminary Surface Infrastructure Design, Doris North Project, Hope Bay, Nunavut, Canada. Report submitted to Miramar Hope Bay Limited, October, 2005. SRK Consulting (Canada) Inc., 2005b. Preliminary Tailings Dam Design, Doris North Project, Hope Bay, Nunavut, Canada. Report submitted to Miramar Hope Bay Limited, October 2005. SRK Consulting (Canada) Inc., 2005c. Water Quality Model, Doris North Project, Hope Bay, Nunavut, Canada. Report submitted to Miramar Hope Bay Limited, October 2005.
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Figures
[INCORRECTLY IDENTIFIED BY FRONTIER GEOSCIENCES]
CORRECT LOCATION OF PROPOSED DOCK
DORIS NORTH PROJECT Preliminary Jetty Design
Roberts Bay Bathymetry (per Frontier Geosciences Inc.)
MIRAMAR HOPE BAY LIMITED
PROJECT:
DATE:
1CM014.006 Sept. 2005 File Ref: Fig 3_Prelim Jetty_Roberts B_20050526.ppt
APPROVED:
EMR
FIGURE:
3
Appendix A MHBL Technical Memorandum
MIRAMAR HOPE BAY LTD. 311 West First Street, North Vancouver, B.C. V7M 1B5 Telephone: 604-985-2572 fax 604-980-0731
MEMORANDUM
TO: Cc: FROM: SUBJECT: DATE:
B. Labadie E. Mahoney Investigation of Barge Landing Area Sept. 15, 2002
Executive Summary Investigation was done into the suitability of the area proposed in the Scoping Study for a barge landing area with the assistance of Steven McKnight, master of the MV Edgar Kotokak, the tug delivering supplies to Roberts Bay. The presently proposed barge landing area would be suitable for use, provided that a causeway roughly 100m long were constructed with a landing area on the end of it. The MV Edgar Kotokak did a sea trial approach to this landing area to ensure that there would be sufficient manoevering room. As the causeway would be in water depths averaging 1m or less, construction costs of this should be manageable. Additional recommended work should include: • Actual measurements of tidal variation in Roberts Bay • More detailed bathymetry in the southern area of Roberts Bay (several days in a small boat equipped with a depth sounder and GPS). • Investigation into the permitting issues related to construction of a causeway from the shore
Details Investigation was done into the suitability of the area proposed in the Scoping Study for a barge landing area. Concerns included the shallow nature of the water close to shore and the room to manoever the barges and tug in somewhat restricted waters. The proposed site would be the optimal one to use if possible, as it would require minimal construction of all-weather road.
Currently Proposed Site
C:\Documents and Settings\mrykaart\My Documents\Barge Landing Investigation (Ted).doc 5/25/2005 6:21:11 PM
The currently used barge offloading site is a very good location as there is deep water just off the shore, and it is in an area where Roberts Bay is quite open. In order to use this location during the mine operation (provided an all weather road is to be constructed) 2 km of all weather road and a bridge crossing of a stream would have to be constructed. The costs of this additional construction make it unattractive. Water Level Variations Roberts Bay has very low tidal variation, likely less than 0.5m, and it has been reported that a strong NW wind can increase water depths by 0.5m and a strong SE wind can decrease it a similar amount. Vessels Currently Used The tugs and barges employed by NTCL are shallow draft vessals, with the tugs drawing roughly 2m of water. A fully loaded series 1500 barge, carrying 1,500 tonnes of deck cargo and 1 million litres of fuel will draw 2m of water as well. A series 1500 barge is 250 ft. long and 55 feet wide. The MV Edgar Kotokak arrived at Roberts Bay on Sept. 15th, under the command of Steven McKnight. It was pulling a series 1500 barge, with significant deck cargo, but no fuel in its holds. It was pushed nose into the beach at the currently used barge landing site. The nose of the barge grounded in 1m of water and forklifts began to offload cargo. NTCL Assistance Mr. Gordon Norberg, of NTCL had previously informed us that the master of the tug which delivered supplies to Roberts Bay this year would be able to inform us of the suitability of a proposed landing site for their use. I discussed the potential offloading site, and a few alternatives, with Mr. McKnight, and we reviewed ortho photos of the area, topo maps, and the government navigation chart for Roberts Bay. We flew the area in a helicopter, looking at possible sites, then scouted it in an aluminum runabout. Mr. McKnight used a sounding pole from the runabout to check depths near shore in several locations. As a final check, the MV Edgar Kotokak disengaged from the barge, and was piloted in to the southern end of Roberts Bay to determine if there was sufficient manoevering room in that somewhat restricted area. Information Resulting from Investigation One thing that was apparent from all of this data, is that near the shore of the southern area of Roberts Bay the water is very shallow and the bottom slopes gently for a distance out to where there is a drop-off. On the accompanying air photo there is a very noticeable change in color in the water where this drop-off occurs. From the soundings taken, it appears that the water depth at the edge of this drop-off is 1.0 and 1.5m. It is unlikely that any barge could get much closer to shore than the edge of the drop-off. An examination of the southern area of Roberts Bay was done to see if there was a location more suitable than that proposed here, or where the required causeway could be shortened. It was concluded that the best location is that currently proposed.
2
Design Considerations for Causeway • Any causeway constructed would need to be wide enough for equipment to travel safely over in unloading the barge. • Bollards to attach the barge to, or pre-set anchor points on shore would need to be present. • It would be best if the unloading area at the end of the causeway were designed to allow for a barge to pull alongside. This would require a length of approximately 50 to 75 ft. (15 to 23m).
3
Roberts Bay Proposed Ba rge Landing Causeway Location
Ta nk Farm La ydown Area
Not Suitable
Causewa y
C:\Documents and Settings\mrykaart\My Documents\Barge Landing Investigation (Ted).doc 5/25/2005 6:21:11 PM
Appendix B Roberts Bay Bathymetry Report (Frontier Geosciences 2003)
STEFFEN, ROBERTSON & KIRSTEN (CANADA) INC. REPORT ON MARINE BATHYMETRY SURVEY PROPOSED ROBERTS BAY DOCKING FACILITIES CAMBRIDGE BAY AREA, NUNAVUT
by Russell A. Hillman, P.Eng.
September, 2003 PROJECT FGI-727 ______________________________________________________________ Frontier Geosciences Inc. 237 St. Georges Avenue, North Vancouver, B.C., Canada V7L 4T4 Tel: 604.987.3037 Fax: 604.984.3074
(i)
CONTENTS page 1
1. INTRODUCTION 2. THE MARINE BATHYMETRY SURVEY 2.1 Equipment 2.2 Survey Procedure
3 3 4
3. GEOPHYSICAL RESULTS 3.1 General 3.2 Discussion
5 5 5
4. SUMMARY
6
ILLUSTRATIONS location Figure 1 Figure 2
Survey Location Plan Bathymetry Contour Plan
Frontier Geosciences Inc.
Page 2 Appendix
1
1.
INTRODUCTION
In the period September 8 to September 13, 2003, Frontier Geosciences Inc. carried out an overwater bathymetric survey for Steffen, Robertson and Kirsten (Canada) Inc., at Roberts Bay, Nunavut. A Survey Location Plan of the area is shown at an approximate scale of 1:5,000,000 in Figure 1. The investigation was carried out to determine water depths in an area proposed for docking facilities. The survey area is located at the southern extremity of Roberts Bay. The marine bathymetry survey covered an area approximately 2.4 km north-south by approximately 1 km east-west.
Frontier Geosciences Inc.
2
65°N
SITE LOCATION
ARCT IC CIRCL E
60°N
115°W
110°W
100°
105°W
0
50
100 150 KILOMETRES
200
APPROXIMATE SCALE 1:5,000,000 NUNAVUT
YUKON NORTHWEST TERRITORIES
SRK CONSULTING ROBERTS BAY, NUNAVUT
HYDROGRAPHIC SURVEY
SURVEY LOCATION PLAN FRONTIER GEOSCIENCES INC. DATE: SEPT. 2003
FIG. 1
3
2.
THE MARINE BATHYMETRY SURVEY
2.1
Equipment
The overwater bathymetric survey was completed with a Marinetek, PCS-200 sounder. The system was calibrated with respect to water temperature and water salinity and used a broadband output with a 200 kHz centre frequency. Power for the field computer and Marinetek Sounder was provided by a portable, 120 volt, AC generator set. The work was carried out with a local, six metre, Lund aluminum survey boat powered by an outboard motor. Tidal fluctuations during the survey were monitored by a tide pole placed at low water, in the southeast corner of the survey area. The tide pole location was surveyed in from a control point (SAS 35) established by the surveyor. This control point located at 7,563,703.47N, 432,943.85E, is at an elevation of 14.18 m. The base of the tide pole was determined to be at an elevation of -0.1 m. In the course of the survey, the tide pole was checked two to three times a day with water level fluctuations noted to vary from -0.1 m to 0.3 m. These increases in water level were subtracted from the data, thus correcting the data to the -0.1 m elevation at the base of the tide pole. The GPS system utilised in the survey was a high resolution, DGPS (Differential Global Positioning System) Max. Differential GPS uses two receivers to cancel out atmospheric errors and Selective Availability (SA). The additional receiver is placed at a known location and makes the same measurements as the roving receiver. The base receiver compares its readings from its known position to that of satellites and creates a difference between the two. This difference is made available to the roving receiver as differential correction information. This correctional information allows the roving receiver to calculate its true location. Information for receiver locations and corrections was provided by the Omnistar system.
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4
2.2
Survey Procedure
The bathymetric transducer was placed in the water at a depth of 0.15 metres on the starboard side, 1 metre forward of the transom. The transducer location was carefully determined to facilitate the best operating environment for the transmission and reception of sound pulses. In operation, the source transducer pulsed twice every second with a sounding frequency of 200 KHz. The pulses emitted from the transducer were reflected by the sea bottom, then digitally recorded and visually reviewed in real time on the high resolution display of the notebook computer. The digital record of the reflected signal was stored in the notebook hard drive and played back to interpret the water depth. The bathymetric data was correlated with the GPS data to accurately plot each pulse position to be contoured for final data presentation. The bathymetry plan used the positioning datum of NAD83 in UTM grid coordinates.
Frontier Geosciences Inc.
5
3.
GEOPHYSICAL RESULTS
3.1
General
The results of the overwater bathymetric survey are shown in colour contour format at a scale of 1:7,500 in Figure 2. The bathymetry data was reduced to local datum, which was the base of a tide pole located at low water in the southeast corner of the survey area. 3.2
Discussion
The bathymetry data indicates the presence of an elongate, north-south trending channel defined generally by the 5 m contour in the south and water depths in excess of 30 m, to the north. The channel is quite broad to the north but narrows to a width of about 150 m in the south. A localised, deeper water depression is also evident in the middle of the survey area and west of the island in the northeast segment of the area. This area is bounded to the north however, by a region of relatively shallow water depths. In the area of the proposed dock structure, water depths are shallow and are of the order of 1 metre. Limited boat draft and numerous boulder hazards limited more detailed coverage of this area. Water depths of 2 metres are extant about 150 m northwest of the shoreline, at the proposed dock location.
Frontier Geosciences Inc.
6
4.
SUMMARY
An overwater bathymetry survey was carried out over a segment of Roberts Bay in Nunavut. The survey area is the site of a proposed docking structure and approaches for ocean-going vessels. The information in this report is based upon acoustic measurements and field procedures and our interpretation of the data. The results are interpretive in nature and are considered to be a reasonably accurate presentation of the ocean bottom configuration within the limits of the overwater bathymetry method.
For: Frontier Geosciences Inc.
Russell A. Hillman, P.Eng.
Frontier Geosciences Inc.
7565600N
7565500N
7565400N
7565300N
7565200N
7565100N
ISLAND 7565000N
7564900N
7564800N
7564700N
7564600N
7564500N
7564400N
7564300N
7564200N
7564100N
7564000N
7563900N
7563800N
7563700N
7563600N
7563500N
7563400N
7563300N
APPROXIMATE LOCATION OF PROPOSED DOCK
7563200N 431500E
431600E
0.0
1.9
431700E
3.8
431800E
5.7
431900E
7.7
432000E
9.6
12.6
432100E
17.1
432200E
23.0
432300E
432400E
432500E
432600E
432700E
432800E
SRK CONSULTING ROBERTS BAY, NUNAVUT
DEPTH (m)
HYDROGRAPHIC SURVEY
INSTRUMENT: MARINETEK PCS-200
0
100
200
300
400
BATHYMETRY CONTOUR PLAN
METRES DATUM: NAD83 UTM ZONE 13 NOTE: SHORELINE APPROXIMATE
FRONTIER GEOSCIENCES INC. DATE: SEPT. 2003
SCALE 1:7,500
FIG. 2
Appendix C Summary of Roberts Bay Geotechnical Properties
Summary of Lab & In-Situ Data Available for Roberts Bay Marine Sediments (SRK 2004 drill program & EBA 1997 drill program)
Sample ID SRK45 15-16.4 m SRK46 4.7 - 6.2 m SRK47 2.1 - 3.6 m SRK49 14.1 - 17.1 m SRK49 5.1 - 8.1 m EBA BH-12 2.44 - 2.59 m EBA BH-15 3.96 - 4.57 m EBA BH-18 4.27 - 4.57 m EBA BH-19 0 - 0.61 m EBA BH-28 3.81 - 4.42 m EBA BH-29 2.59 - 2.74 m
Water Liquid Lab Soil Content Limit Classification (%) (%) CL 34.8 42 CL 56.8 39 CL 37.2 34 CL 58.6 38 CL 32.6 22 CL 47.3 40.5 CL 67.5 41 CL 43 42 CL 34.4 26 CL 40.8 30 CL 63.3 43
Plastic Limit Plasticity (%) Index (%) % Clay % Silt 24 18 22 17 18 16 22 16 15 7 22 18.5 44.2 39.8 18 23 52.5 43.2 20 22 54.8 38.6 14 12 61.5 34.4 16 14 46.4 29 25 18 46.8 44.6
% Sand
16 4.3 6.6 3 23.4 8.6
Passing Undrained Shear 2micron Strength (%) Bulk UU READ Density % from Passing in Tube Triaxial Vane Gravel #200 (%) (kPa) PSD Activity (Mg/m3) (kPa) 94.5 49 0.37 94.8 43 0.40 93.7 27 0.59 96.4 39 0.41 76.7 20 0.35 0 84 35 0.53 0 95.7 43 0.53 1.8 14 5.5 0 93.4 45 0.49 1.1 95.9 49 0.24 1.82 8.5 5 1.2 75.4 32 0.44 0 91.4 37 0.49
EBA BH-15 3.05 - 3.2 m EBA BH-26 3.05 - 3.66 m
CH CH
74.8 70
52.5 56
29 23
23.5 33
56.1 17.5
41 47.3
2.9 35.2
0 0
97.1 64.8
41 11
0.57 3.00
EBA BH-11 0.91-1.07 m
CL-ML
26
21
14
7
28
26.5
45.5
0
54.5
22
0.32
SRK46 12.3 - 13.8 m EBA BH-24 6.10 - 6.86 m EBA BH-28 9.91 - 10.52 m
SP SP SP
20 26.4 28.4
np
np
np 6
82.9 84.9
0 0.1
7.7 17.1 15
0 9
np
11.1
EBA BH-18 0 - 0.61 m EBA BH-24 2.74 - 3.35 m EBA BH-26 3.96 - 4.57 m EBA BH-30 4.57 - 5.18 m NOTES: np = non plastic Yellow cells indicate there is no data available
31.5 31.6 94.6 45.9
15
1.78
1.86 1.25 1.58 2.08
3
27.5
12 2 5 7.6
Appendix D Phase I Foundation Investigation (SRK 2004)
Phase I Foundation Investigation Proposed Roberts Bay Jetty Location, Doris North Project, Nunavut, Canada
Prepared for
Miramar Hope Bay Limited
Prepared by
April 2004
Phase 1 Foundation Investigation Proposed Roberts Bay Jetty Location, Doris North Project, Nunavut, Canada
Miramar Hope Bay Limited Suite 300, 889 Harbourside Drive North Vancouver, BC V7P 3S1
SRK Consulting (Canada) Inc. Suite 800, 1066 West Hastings Street Vancouver, B.C. V6E 3X2
Tel: 604.681.4196 Fax: 604.687.5532 E-mail:
[email protected] Web site: www.srk.com
SRK Project Number 1CM014.02
April 2004
Author Dylan MacGregor, M.A.Sc., G.I.T.
Reviewed by Maritz Rykaart, Ph.D., P.Eng. Senior Geotechnical Engineer
SRK Consulting Phase 1 Foundation Investigation Proposed Roberts Bay Jetty Location
Page i
Table of Contents 1 Introduction .................................................................................................................. 1 1.1 Background ......................................................................................................................... 1 1.2 Summary of Drill Program ................................................................................................... 1
2 Methodology................................................................................................................. 2 2.1 Drilling ................................................................................................................................. 2 2.2 Laboratory Testing .............................................................................................................. 2
3 Results .......................................................................................................................... 3 3.1 Drilling Hole Locations ........................................................................................................ 3 3.2 General Drilling Conditions ................................................................................................. 3 3.3 Foundation conditions ......................................................................................................... 4 3.3.1 3.3.2 3.3.3 3.3.4
SRK 47 ....................................................................................................................................4 SRK 46 ....................................................................................................................................4 SRK 45 ....................................................................................................................................5 SRK 49 ....................................................................................................................................5
3.4 Laboratory Testing Results ................................................................................................. 5
4 Discussion.................................................................................................................... 6 5 References.................................................................................................................... 8
List of Tables Table 1: Initial Laboratory Testing Program for Samples from Roberts Bay Geotechnical Drilling, Winter 2004 ........................................................................................................................ 2 Table 2: As-built Drillhole Coordinates, Roberts Bay Geotechnical Drilling, Winter 2004 ................ 3 Table 3: Results of Initial Laboratory Testing Roberts Bay Geotechnical Drilling, Winter 2004 ....... 6
List of Figures Figure 1: Proposed Jetty Layout Figure 2: Drill Hole Locations Figure 3: Inferred Jetty Centerline Profile
List of Attachments Attachment A: Drill Logs Attachment B: Laboratory Test Results
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1
Introduction
1.1
Background
Page 1
An eleven day visit to Miramar’s Doris North Project was made by Dylan MacGregor (GIT) of SRK Consulting during the period of April 10-20, 2004. The primary purpose of this work was to conduct a geotechnical drilling program at the south end of Roberts Bay. The drilling program targeted foundation conditions in the footprint of the proposed jetty (Figure 1) described in the preliminary surface infrastructure design report (SRK 2003). Specific goals of the drilling program consisted of the following: •
determine water depth along the proposed jetty alignment;
•
determine overburden thickness along the proposed jetty alignment;
•
collect soil samples for laboratory testing of soil properties;
•
determine underlying bedrock characteristics.
The following memo describes the findings of the April 2004 geotechnical drilling program and summarizes the collated results. Drill logs, a plan layout of borehole collars, and a section along the alignment of the proposed jetty, including the new geotechnical information, are included.
1.2
Summary of Drill Program A series of three holes (SRK 45, SRK 46, and SRK 47) were planned along the alignment of the proposed jetty at the south end of Roberts Bay. Two optional holes (SRK 48 and SRK 49) were also under consideration, to be drilled if determined necessary on the basis of initial drilling results. One of these optional holes (SRK 49) was deemed necessary to further define foundation conditions at the loading terminus of the jetty. Proposed drillhole locations are shown in Figure 2. Seasonal weather conditions prevailed for the duration of the drilling operation. Winds were generally from the north at 5 to 20 km/h, with daytime temperatures of up to -5°C and overnight lows of -25°C. During the day, conditions ranged from sunny to high overcast.
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SRK Consulting Phase 1 Foundation Investigation Proposed Roberts Bay Jetty Location
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Methodology
2.1
Drilling
Page 2
Drilling was conducted by Major Drilling, using a Boyles Brothers 37 diamond drill operating 24 hours/day with two - 12 hour shifts. All holes were drilled at an angle of -90°. Core was NQ3 size (45.1 mm diameter) and was drilled in runs of 1.5 m for boreholes SRK 46 and SRK 47 using the triple tube coring technique. For boreholes SRK 45 and SRK 49, core was NQ size (47.6 mm diameter) and drilled in runs of 3 m using the standard diamond drilling technique. Holes were targeted to fully penetrate the overburden sediments and to sample the upper 5 m of bedrock. Samples of recovered overburden were collected for foundation indicator testing; samples were shipped to EBA Engineering’s soil testing lab in Yellowknife. Rock core was logged by Miramar geologists according to standard exploration procedures, which include geotechnical characterisation. As-built drillhole collars were surveyed by Miramar’s surveyor.
2.2
Laboratory Testing A limited selection of samples, including at least one sample from each drillhole, were initially selected for foundation indicator testing by EBA Engineering. Particle size distribution tests were conducted, as well as moisture content and Atterberg Limits determinations where appropriate, all according to standard soils testing procedures. Table 1 outlines the initial testing program.
Table 1: Initial Laboratory Testing Program for Samples from Roberts Bay Geotechnical Drilling, Winter 2004 SampleID
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Field Soil Classification
Particle size distribution Sieve
Hydrometer
Water Content Determination
Atterberg Limits
SRK45 15 - 16.4 m
CL
9
9
9
SRK46 4.7 - 6.2 m
CL
9
9
9
SRK46 12.3 - 13.8 m
SP
SRK47 2.1 - 3.6 m
CL
9
9
9
SRK49 5.1 - 8.1 m
CL
9
9
9
SRK49 14.1 - 17.1 m
CL
9
9
9
9
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Results
3.1
Drilling Hole Locations
Page 3
The as-built collar locations differed slightly from planned locations; drill collars were surveyed following drilling to record the as-built drillhole locations. Table 2 provides the surveyed coordinates for the four Roberts Bay geotechnical drillholes.
Table 2: As-built Drillhole Coordinates, Roberts Bay Geotechnical Drilling, Winter 2004 HoleID
Northing1
Easting1
Elevation2
Inclination
SRK45
7563322.36
432531.51
-0.02
-90°
SRK46
7563299.16
432543.76
0.02
-90°
SRK47
7563272.79
432552.12
-0.07
-90°
SRK49
7563337.64
432525.12
-0.34
-90°
1. UTM Projection NAD 83 Zone 13. 2. Negative values represent collar elevation below survey grid datum.
Drilling results are summarized in a series of borehole logs. The complete logs are included here as Attachment A, and a profile through the drillholes (Figure 3) displays the interpreted stratigraphy along the proposed jetty centreline. The following briefly discusses drilling conditions and materials encountered in each drillhole.
3.2
General Drilling Conditions SRK 47 was drilled April 16-17, 2004. Water was hauled from Doris Lake to provide drilling fluid via a dozer hauling a water tank, as Major Drilling considered that it would take too much time to move the large pump from Doris Lake to Roberts Bay. SRK 46 was drilled on April 17, 2004. Frank Ratte, a Miramar geologist, supervised the upper 14.3 m of drilling. An attempt was made to obtain seawater for drilling by augering a hole through the sea ice near the collar of SRK 45 and pumping water to the drill’s holding tank using a small portable Honda pump. This effort met with mixed success, with the pump performing poorly and eventually freezing up. Ultimately the large pump was mobilized from Doris Lake and a reliable supply was established using seawater. At the start of the program, two NQ3 drill bits were available. These bits are required in order to use the triple tube coring technique, as they cut a narrower diameter core than standard NQ bits. This narrower core allows for the thickness of a split tube inside the core tube. While drilling through the sand and gravel unit in SRK 46, one NQ3 drill bit was consumed. Pieces of the face of this bit were later recovered after replacing the drill bit. The replacement bit was able to finish drilling borehole SRK 46.
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During final breakdown and removal of the rod string from SRK 46, it was necessary to remove the core barrel and bit with the head open because the core barrel would not fit through the chuck jaws. A small clamp with a 0.3 m arm perpendicular to the clamp axis was fixed to the core barrel to prevent it from falling back into the drill hole. The rod string was broken at the top of the core barrel immediately below the head, and the rods were pulled up through the head. The core barrel and clamp were lowered down such that the clamp arm was supported by part of the frame of the drill shack. While the drillers were removing the rod from the head, the clamp holding the core barrel was jarred loose, and the clamp and core barrel spun off of the frame and fell down the drill hole. Attempts to fish the core barrel/ clamp unit out of the drill hole were unsuccessful. As the drill bit remained fixed to the core barrel during this process, the second and last available NQ3 drill bit was lost as a result of this mishap. SRK 45 was drilled on April 17, 2004, using a NQ drill bit and standard exploration wireline coring techniques. All sediment in SRK 45 was drilled without an inspector present, and recovered material was boxed for later inspection. Recovery was generally poor. As a result of the poor recoveries achieved at SRK 45, compounded by the apparent change in geological materials along the long section of the proposed jetty, it was decided to drill optional hole SRK 49. The information from this additional drill hole would better define foundation conditions expected at the critical loading terminus of the jetty, where a large proportion of total rock fill is expected to be placed. SRK 49 was drilled on April 18, 2004, using a NQ drill bit and standard exploration wireline coring techniques. All sediment in SRK 49 was cored without rotating drill rods. Rods were advanced by downward head pressure alone. An inspector was present for the duration of drilling of SRK 49.
3.3
Foundation conditions
3.3.1 SRK 47 The borehole log for SRK47 is included in Attachment A. Sea ice was found to be 0.6 m thick and frozen to the seabed. Overburden extended from 0.6 m to 9.8 m, and consisted of an upper 3.1 m thick frozen unit of silt and clay underlain by 6.1 m of sand and gravel. Recovery of sample in the sand and gravel unit was generally poor. Bedrock was intersected at 9.8 m depth and cored to a depth of 14 m. The rock consisted of a fine grained grey-green basalt with an RQD of 80% and greater.
3.3.2 SRK 46 The sea ice at SRK 46 was found to be 2.3 m thick; the borehole log for SRK46 is included in Attachment A. It appears that the sea ice was frozen to the bed sediments, although one of the drillers reported that there had been a small depth of liquid water above the sediment. The upper
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sediments consisted of 4.9 m of frozen ice-rich silt and clay. These were underlain by 9 m of sand and gravel. Poor sample recovery was experienced across the sand and gravel unit. Bedrock was intersected 17.2 m below the collar elevation and consisted of medium to coarse grained gabbro, having RQD values ranging from 57 to 84%.
3.3.3 SRK 45 Sea ice at SRK 45 was approximately 2 m thick, and covered approximately 3 m of unfrozen seawater; the borehole log for SRK45 is included in Attachment A. The surface sediments appeared to be 4 m of uniform fine grey sand. In general, recovery was poor for this unit, there was no intact core recovered, and the material was visually dissimilar to other sands encountered in adjacent holes to the south during the Winter 2004 geotechnical drilling program and previous geotechnical drilling programs in the broader area. For these reasons, the material sampled over the 5 to 11 m interval is considered to be anomalous and not to be representative of the foundation conditions in the area of the proposed causeway. Due to the fact that an SRK inspector was not present during the drilling of this hole, together with the poor recovery, the value of data from this hole is somewhat questionable. From 11 to 13 m below the collar elevation, recovery improved to 50% and the material made a transition from sand to fine grained soil. From 13 to 14.4 m, the material was a uniform, grey silt and clay with high water content. This fine grained material overlay basalt bedrock. SRK 45 was terminated after drilling 4.6 m of basalt; RQD ranged from 52 to 56%.
3.3.4 SRK 49 The borehole log for SRK49 is included in Attachment A. Sea ice at SRK 49 was 1.7 m thick, and sea water beneath the ice extended to 5.1 m below the collar. Water depth at SRK49 was measured using a weighted sounding line dropped through the drill rods following penetration of sea ice, and is considered to be very accurate. Sediment encountered at 5.1 m was a dark grey fine grained material that extended to the bedrock contact at 17.35 m. Water content appeared to increase with depth, and organic content appeared to decrease with depth. The colour of the material changed from a dark grey at surface to a medium grey at depth, and was considered to reflect the organic content of the soil. Felsic volcaniclastic bedrock was cored from 17.35 m to 21.6 m. Bedrock RQD was moderately poor and ranged from 34 to 37%.
3.4
Laboratory Testing Results A subset of five fine-grained samples and one coarse-grained sample were subjected to an initial stage of foundation indicator testing. Table 3 summarizes the sample origins and the test results. Complete results are included as Attachment B.
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Table 3: Results of Initial Laboratory Testing Roberts Bay Geotechnical Drilling, Winter 2004
4
SampleID
Lab Soil Classification
Water Content (%)
Liquid Limit (%)
Plastic Limit (%)
Plasticity Index (%)
SRK45 15 - 16.4 m
CL
34.8
42
24
18
SRK46 4.7 - 6.2 m
CL
56.8
39
22
17
SRK46 12.3 - 13.8 m
SP
20
na
na
na
SRK47 2.1 - 3.6 m
CL
37.2
34
18
16
SRK49 5.1 - 8.1 m
CL
32.6
22
15
7
SRK49 14.1 - 17.1 m
CL
58.6
38
22
16
Discussion Figure 3 shows a longitudinal profile along the proposed jetty which shows the stratigraphy inferred from the recent drilling results. Water depth was generally found to be slightly greater than expected based on the bathymetry data (Frontier Geosciences 2003), with ice + water depths of 5 m in the vicinity of the proposed jetty terminus. In the near-shore sediments sampled in holes SRK46 and SRK47, an upper layer of fine-grained material overlies a sand and gravel unit. This coarse-grained unit lies directly on bedrock, and appears to pinch out to the north between SRK46 and SRK45, as shown in Figure 3. In SRK45, the upper sediments consist of uniform fine grey sand. No intact core of this material was obtained, and recovery was generally poor. The fine grey sand recovered from SRK45 is distinctly different from the coarse granitic sand encountered in SRK47 and SRK46, as well as elsewhere across the project site. This fine sandy material is interpreted to be distinct from the coarse sand and gravel unit directly on bedrock to the south. The fine-grained sediment in SRK45 rests directly on bedrock and appears similar to the fine-grained material to both north and south. This unit is inferred to be continuous along the proposed jetty profile as shown in Figure 3. Drilling data indicates a local bedrock high in the vicinity of SRK45. The northernmost drillhole, SRK49, encountered 5 m of water over approximately 12 m of fine grained silt and clay, as shown in Figure 3. The fine-grained unit extends from the sediment-water interface to the bedrock contact, and varies uniformly from a dark grey organic rich material at surface to a medium grey material with no visible organics at depth. The material is very soft, with high water content, throughout the interval. Special consideration must be given to foundation design for any infrastructure to be built on this material.
MR/spk
Phase1FoundationInvestigation.Report.1CM014.02.MR.Rev02.doc, May. 26, 05, 3:10 PM
April 2004
SRK Consulting Phase 1 Foundation Investigation Proposed Roberts Bay Jetty Location
Page 7
This report, “Phase I Foundation Investigation Proposed Roberts Bay Jetty Location, Doris North Project, Nunavut, Canada”, has been prepared by SRK Consulting (Canada) Inc.
Prepared by:
Dylan MacGregor, M.A.Sc., G.I.T.
Reviewed by:
Maritz Rykaart, Ph.D., P.Eng. Senior Geotechnical Engineer
MR/spk
Phase1FoundationInvestigation.Report.1CM014.02.MR.Rev02.doc, May. 26, 05, 3:10 PM
April 2004
SRK Consulting Phase 1 Foundation Investigation Proposed Roberts Bay Jetty Location
5
Page 8
References Frontier Geosciences Inc., 2003. Report on Marine Bathymetry Survey, Proposed Roberts Bay Docking Facilities, Cambridge Bay Area, Nunavut. Report submitted to SRK Consulting, September 2003. SRK Consulting, 2003. Surface Infrastructure Preliminary Design, Doris North Project, Nunavut, Canada. Report submitted to Miramar Hope Bay Ltd., October, 2003.
MR/spk
Phase1FoundationInvestigation.Report.1CM014.02.MR.Rev02.doc, May. 26, 05, 3:10 PM
April 2004
Figures
Attachment A Drill Logs
HOLE NO: SRK 45
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 18, 2004
SURFACE (COLLAR) ELEVATION: -0.02 m
DATE AND TIME FINISHED: April 18, 2004 EASTING: 432531.51
DRILL CONTRACTOR: Major Drilling
Installations
DIP vertical steep medium shallow horizontal
Sample
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
Separation
ROUGHNESS smooth sl. rough medium rough v. rough
Roughness
0.6
Hardness
0.2
Weathering
FABRIC v. fine fine medium coarse v. coarse
Fabric
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Contact (m)
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
Depth (m)
DRILLING METHOD: Diamond Drill Core
RQD
LOGGED BY: Dylan MacGregor
Soil Class
NORTHING: 7563322.36
Sea ice (estimated thickness)
1
2
1
2.0
Sea water
3
2
4
5
5.0
Fine gray sand, no fines recovered. Core not intact.
6
SP
3
25%
SP
4
25%
7
8
8.0
SP as above.
9
10
Sheet 1 of 2
HOLE NO: SRK 45
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 18, 2004
SURFACE (COLLAR) ELEVATION: -0.02 m
DATE AND TIME FINISHED: April 18, 2004 EASTING: 432531.51
DRILL CONTRACTOR: Major Drilling
Installations
DIP vertical steep medium shallow horizontal
Sample
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
Separation
ROUGHNESS smooth sl. rough medium rough v. rough
Roughness
0.6
Hardness
0.2
Weathering
FABRIC v. fine fine medium coarse v. coarse
Fabric
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Depth (m)
Contact (m) 11.0
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
11
DRILLING METHOD: Diamond Drill Core
RQD
LOGGED BY: Dylan MacGregor
Soil Class
NORTHING: 7563322.36
Transition from fine sand above to finer grained material below. SRK45 10-13 m
12
13
13.0
SM
5
50%
CL
6
100%
7
90%
Grey, fine grained, slight organic smell, soft, high water content, some plasticity.
14 14.4
15
BASALT, pale green, fine grained to massive. Brecciated from 15.11m to EOH. Fractures filled with hematite and calcite. 56%
16
SRK45 15-16.4m 16.0
17
52%
8
97%
18
19
19.0 EOH
20
Sheet 2 of 2
HOLE NO: SRK 46
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 17, 2004
SURFACE (COLLAR) ELEVATION: 0.02 m
DATE AND TIME FINISHED: April 17, 2004 EASTING: 432543.76
DRILL CONTRACTOR: Major Drilling
Installations
DIP vertical steep medium shallow horizontal
Sample
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
Separation
ROUGHNESS smooth sl. rough medium rough v. rough
Roughness
0.6
Hardness
0.2
Weathering
FABRIC v. fine fine medium coarse v. coarse
Fabric
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Contact (m)
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
Depth (m)
DRILLING METHOD: Triple Tube Core
RQD
LOGGED BY: Frank Ratte, Dylan MacGregor
Soil Class
NORTHING: 7563299.16
Sea ice
1
1
2 2.3 2.55
ICE + ML Vr, 25-30% ice. Grey silt with sand.
ICE + ML
3
ML 3.8 4
100%
2
100%
SRK46 0.55-1.66
Vr, 0.5% ice. Grey, fine grained CL, trace shells. CL
3
100%
SRK46 1.8-3.2
CL
4
100%
SRK46 3.2-4.7
CL
5
100%
SRK46 4.7-6.2
SP
6
5%
5 5.2
Vr, 5-15% ice. Grey, fine grained CL.
6
6.7
Vr, 5-35% ice. Grey, fine grained CL.
7
8 8.2
Vr. Gravel with minor sand - poor recovery
9
9.7
LOSS
10
Sheet 1 of 3
HOLE NO: SRK 46
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 17, 2004
SURFACE (COLLAR) ELEVATION: 0.02 m
DATE AND TIME FINISHED: April 17, 2004 EASTING: 432543.76
DRILL CONTRACTOR: Major Drilling
0%
Loss
8
0%
SP
9
80%
Installations
7
0.6
DIP vertical steep medium shallow horizontal
Sample
Loss
0.2
Fabric
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
ROUGHNESS smooth sl. rough medium rough v. rough
Separation
Hardness
Weathering
FABRIC v. fine fine medium coarse v. coarse
Roughness
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Contact (m)
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
Depth (m)
DRILLING METHOD: Triple Tube Core
RQD
LOGGED BY: Frank Ratte, Dylan MacGregor
Soil Class
NORTHING: 7563299.16
11 11.2
LOSS (recovered 1-5 cm gravel particle)
12
12.7
Granitic sand, no ice.
13
SRK46 10.7-12.3
14 14.3 14.55 15
15.15 15.2
Granitic gravel Granitic sand, coarsening upwards from fine to coarse, trace fines. Single granitic gravel particle. LOSS
15.8 16
16.8 17 17.2
Gravel, subangular to subrounded, particles average 3 cm diameter with maximum of 9 cm diameter, with lesser coarse sand.
Gravel as above. GABBRO, dark green and grey, medium to coarse grained, non-magnetic, fractures filled with chlorite and hematite, abundant calcite veining.
GP
100% 100%
SP
10
SP Loss
100%
SRK46 12.3-13.8
0%
GP
11
GP
100%
SRK46 13.8-14.8
100%
12 100%
84%
18 18.3
GABBRO, as above.
19
84%
19.8 20
13
95%
GABBRO, as above.
Sheet 2 of 3
HOLE NO: SRK 46
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 17, 2004
SURFACE (COLLAR) ELEVATION: 0.02 m
DATE AND TIME FINISHED: April 17, 2004 EASTING: 432543.76
DRILL CONTRACTOR: Major Drilling
95%
Installations
14
DIP vertical steep medium shallow horizontal
Sample
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
Separation
ROUGHNESS smooth sl. rough medium rough v. rough
Roughness
0.6
Hardness
0.2
Weathering
FABRIC v. fine fine medium coarse v. coarse
Fabric
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Contact (m)
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
Depth (m)
DRILLING METHOD: Triple Tube Core
RQD
LOGGED BY: Frank Ratte, Dylan MacGregor
Soil Class
NORTHING: 7563299.16
21 57%
22
22.8 23
EOH
24
25
26
27
28
29
30
Sheet 3 of 3
HOLE NO: SRK 47
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 16, 2004
SURFACE (COLLAR) ELEVATION: -0.07 m
DATE AND TIME FINISHED: April 17, 2004 EASTING: 432552.12
DRILL CONTRACTOR: Major Drilling
Installations
DIP vertical steep medium shallow horizontal
Sample
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
Separation
ROUGHNESS smooth sl. rough medium rough v. rough
Roughness
0.6
Hardness
0.2
Weathering
FABRIC v. fine fine medium coarse v. coarse
Fabric
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Contact (m)
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
Depth (m)
DRILLING METHOD: Triple Tube Core
RQD
LOGGED BY: Dylan MacGregor
Soil Class
NORTHING: 7563272.79
Sea ice 1 0.6 1
2
2.1
Vr, ice rich (25%). Grey, fine grained, trace black organics, organic smell, moderate plasticity, CL. 90%
SRK47 0.6-2.1m
CL
3
80%
SRK47 2.1-3.6m
CL as above.
CL
4
100%
SRK47 3.6-3.7m
SP
5
5%
SRK47 3.7-5.1m
Loss
6
0%
GP
7
5%
SP
8
10%
GP
9
50%
Nbn. Medium granitic sand, 1-6 cm granitic gravel particle, very poor recovery.
4
5
2
Vr, minor Nbn, possibly rare 1-2 cm unfrozen layers. Grey fine grained material as above, CL.
3
3.6 3.7
CL
5.1
LOSS
6
6.6
Granitic gravel up to 5 cm. Very poor recovery.
7
8
8.1
Sand, minor silt. Very poor recovery.
9
9.6 9.8
Granitic gravel up tp 5 cm. No sand or fines recovered.
SRK47 8.1-9.6m
10
Sheet 1 of 2
HOLE NO: SRK 47
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 16, 2004
SURFACE (COLLAR) ELEVATION: -0.07 m
DATE AND TIME FINISHED: April 17, 2004 EASTING: 432552.12
DRILL CONTRACTOR: Major Drilling
10
100%
80%
11
100%
0.6
Fabric
87%
0.2
DIP vertical steep medium shallow horizontal
Installations
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Sample
Dip (degrees)
Separation
Roughness
Hardness
Weathering
ROUGHNESS smooth sl. rough medium rough v. rough
Recovery
11
FABRIC v. fine fine medium coarse v. coarse
Run
BASALT, pale green, fine grained to massive. Rubble from 12.13 to 12.16 m. Fractures filled with chlorite and hematite. Veinlets make up 1% of rockmass and consist of calcite and hematite. No major veins.
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Contact (m)
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
Depth (m)
DRILLING METHOD: Triple Tube Core
RQD
LOGGED BY: Dylan MacGregor
Soil Class
NORTHING: 7563272.79
11.1
12
13
14
14.0 EOH
15
16
17
18
19
20
Sheet 2 of 2
HOLE NO: SRK 49
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 18, 2004
SURFACE (COLLAR) ELEVATION: -0.34 m
DATE AND TIME FINISHED: April 18, 2004 EASTING: 432525.12
DRILL CONTRACTOR: Major Drilling
Installations
DIP vertical steep medium shallow horizontal
Sample
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
Separation
ROUGHNESS smooth sl. rough medium rough v. rough
Roughness
0.6
Hardness
0.2
Weathering
FABRIC v. fine fine medium coarse v. coarse
Fabric
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Contact (m)
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
Depth (m)
DRILLING METHOD: Diamond Drill Core
RQD
LOGGED BY: Dylan MacGregor
Soil Class
NORTHING: 7563337.64
Sea ice
1
1
1.7
Sea water
2
3 2
4
5
5.1
Dark grey, fine grained material, organic smell, wet, unfrozen CL.
6
CL
3
17%
SRK49 5.1-8.1 m
CL
4
33%
SRK49 8.1-11.1m
7
8
8.1
Material as above.
9
10
Sheet 1 of 3
HOLE NO: SRK 49
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 18, 2004
SURFACE (COLLAR) ELEVATION: -0.34 m
DATE AND TIME FINISHED: April 18, 2004 EASTING: 432525.12
DRILL CONTRACTOR: Major Drilling
75%
SRK49 11.1 14.1 m
CL
6
30%
SRK49 14.1 17.1 m
Sample
5
0.6
Fabric
CL
0.2
Installations
DIP vertical steep medium shallow horizontal
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
ROUGHNESS smooth sl. rough medium rough v. rough
Separation
Hardness
Weathering
FABRIC v. fine fine medium coarse v. coarse
Roughness
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Depth (m)
Contact (m) 11.1
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
11
DRILLING METHOD: Diamond Drill Core
RQD
LOGGED BY: Dylan MacGregor
Soil Class
NORTHING: 7563337.64
Material similar to above. Wet, soft, lighter grey than overlying material.
12
13
14
14.1
Material as above.
15
16
17
17.1 17.35
Material as above.
CL
100%
FELSIC VOLCANICLASTIC, subangular to subrounded clasts in a fine-grained matrix.
18
34%
7
76%
19
20
Sheet 2 of 3
HOLE NO: SRK 49
PROJECT: HOPE BAY DORIS NORTH - WINTER 2004
HOLE DIAMETER: 76 mm (NQ)
PROJECT NO: 1CM014.02 LOCATION: Roberts Bay
DATE AND TIME STARTED: April 18, 2004
SURFACE (COLLAR) ELEVATION: -0.34 m
DATE AND TIME FINISHED: April 18, 2004 EASTING: 432525.12
DRILL CONTRACTOR: Major Drilling
89%
Installations
8
DIP vertical steep medium shallow horizontal
Sample
Recovery
DISCONTINUITY SEPARATION closed v. narrow narrow wide v. wide
Run
Dip (degrees)
Separation
Roughness
Hardness
0.6
Weathering
0.2
ROUGHNESS smooth sl. rough medium rough v. rough
FELSIC VOLCANICLASTIC, subangular to subrounded clasts in a fine-grained matrix. 37%
21
FABRIC v. fine fine medium coarse v. coarse
Fabric
ROCK MASS HARDNESS v. hard hard medium soft v.soft
Fracture Spacing
Contact (m)
Depth (m)
Material Description
WEATHERING unweathered slightly medium highly completely
Lithology
GRADE 1 2 3 4 5
RQD ROCK QUALITY(%) 100 x core lengths 100 mm and longer length of run
20.1
DRILLING METHOD: Diamond Drill Core
RQD
LOGGED BY: Dylan MacGregor
Soil Class
NORTHING: 7563337.64
21.6 EOH 22
23
24
25
26
27
28
29
30
Sheet 3 of 3
Attachment B Laboratory Test Results
EBA Engineering Consultants Ltd. MOISTURE CONTENT TEST RESULTS Project:
SRK 2004 Testing Services
Project No.:
BH No:
1780108
Date Tested: April 29 - April 30, 2004
Location: Client:
SRK -47, SRK -46, SRK -45, SRK -49.
By:
NR
SRK Consulting
Test No.
BH No.Sample No.
Depth (m)
Wet+Tare
Dry+Tare
Tare
% Moisture Content
3560-1
SRK -47
2.1 -3.6
1252
965
194
37.2
Clayey SILT, trace sand, CL
3560-2
SRK -46
4.7 -6.2
1300.8
901.6
199.4
56.8
SILT and CLAY, trace sand, CL
3560-3
SRK -46
12.3 -13.8
1402.4
1209.7
245
20.0
SAND, trace silt
3560-4
SRK -45
15.0 -16.4
1884.4
1448.2
193
34.8
CLAY and SILT, trace sand, CL
3560-5 3560-6
SRK -49 SRK -49
5.1 -8.1 14.1 -17.1
1264.2 2164.9
1001.4 1437.1
196.4 194.9
32.6 58.6
Sandy, clayey SILT, trace sand,CL SILT and CLAY, trace sand, CL
Description
Data presented hereon are for the sole use of the
The testing services reported herein have been performed by an EBA technician to recognized
stipulated client. EBA is not responsible, nor can
industry standards., unless otherwise noted. No other warranty is made. These data do not
be held liable, for use made of this report by any
include or represent any interpretation or opinion of specification compliance or material
other party, with or without the knowledge of EBA.
suitability. Should engineering interpretation be required, EBA will provide it upon written request.
EBA Engineering Consultants Ltd. ATTERBERG LIMIT TEST RESULTS
Project:
SRK 2004 Testing Services
BH No:
SRK 45, SRK 46, SRK 47, SRK 49
Date Tested: April 29 - May 5, 2004 Project No.:
1780108
By:
NR
Location: Client:
SRK Consulting
BH No.
Sample Number
Depth (m)
LL, %
PL, %
PI, %
SRK 47
3560 - 1
2.1 - 3.6
34
18
16
SRK 46
3560 - 2
4.7 - 6.2
39
22
17
SRK 46
3560 - 3
12.3 - 13.8
SRK 45 SRK 49 SRK 49
3560 - 4 3560 - 5 3560 - 6
15.0 - 16.4 5.1 - 8.1 14.1 - 17.1
NP 42 22 38
24 15 22
18 7 16
Data presented hereon are for the sole use of the
The testing services reported herein have been performed by an EBA technician to recognized
stipulated client. EBA is not responsible, nor can
industry standards., unless otherwise noted. No other warranty is made. These data do not
be held liable, for use made of this report by any
include or represent any interpretation or opinion of specification compliance or material
other party, with or without the knowledge of EBA.
suitability. Should engineering interpretation be required, EBA will provide it upon written request.
EBA Engineering Consultants Ltd. GRAIN SIZE DISTRIBUTION PERCENTAGE PASSING
SIEVE
Project: SRK 2004 Testing Services
40
Project Number: 1780108
25
Client: SRK Consulting
20
Attention: Mr. Dylan MacGregor, Project Manager
16
Date Tested: May 4 - May 6, 2004
12.5
Borehole Number: SRK 45
10
Depth:
5
15.0 - 16.4 m
Sample Number: n/a
2.5
100
Lab Number:
3560-4
1.25
100
Soil Description:
CLAY and SILT, trace sand, CL
0.63
100
Natural Moisture Content: 34.8%
0.315
99
Remarks:
0.16
99
0.08
94.5
LL=42%, PL=24%, PI=18%
CLAY
SAND
SILT FINE
GRAVEL
MEDIUM
COARSE
FINE
COARSE
SIEVE SIZES 200
100
100
60
40 30
20 16
10 8
.5
1
2
4
3/8 1/2 3/4 1
11/2 2
90 80
PERCENT SMALLER
70 60 50 40 30 20 10 0 .0005
.001
.002
.005
.01
.02
.05
.1
.2
5
10
GRAIN SIZE (millimeters)
Reviewed By: Data presented hereon is for the sole use of the stipulated client. EBA is not responsible, nor can be held liable, for use made of this report by any other party, with or without the knowledge of EBA
P.Eng.
The testing services reported herein have been performed by an EBA technician to recognized Industry standards, unless otherwise noted, No other warranty is made. These data do not include or represent any interpretation or opinion of specification compliance or material suitability. Should engineering interoperation be required, EBA will provide it upon written request.
20
50
3
EBA Engineering Consultants Ltd. GRAIN SIZE DISTRIBUTION PERCENTAGE PASSING
SIEVE
Project: SRK 2004 Testing Services
40
Project Number: 1780108
25
Client:
20
SRK Consulting
Attention: Mr. Dylan MacGregor, Project Manager
16
Date Tested: May 4 - May 6,2004
12.5
Borehole Number: SRK 46
10
Depth:
5
100
Sample Number: n/a
2.5
100
Lab Number:
3560-2
1.25
100
Soil Description:
SILT and CLAY, trace sand, CL
0.63
100
Natural Moisture Content: 56.8%
0.315
100
Remarks:
0.16
99
0.08
94.8
4.7 - 6.2 m
LL=39%, PL=22%, PI=17%
CLAY
SAND
SILT FINE
GRAVEL
MEDIUM
COARSE
FINE
COARSE
SIEVE SIZES 200
100
100
60
40 30 20 16
10 8
4
3/8 1/2 3/4 1 11/2 2
90 80
PERCENT SMALLER
70 60 50 40 30 20 10 0 .0005 .001
.002
.005
.01
.02
.05
.1
.2
.5
1
2
5
10
GRAIN SIZE (millimeters)
Reviewed By: Data presented hereon is for the sole use of the stipulated client. EBA is not responsible, nor can be held liable, for use made of this report by any other party, with or without the knowledge of EBA
P.Eng.
The testing services reported herein have been performed by an EBA technician to recognized Industry standards, unless otherwise noted, No other warranty is made. These data do not include or represent any interpretation or opinion of specification compliance or material suitability. Should engineering interoperation be required, EBA will provide it upon written request.
20
50
3
EBA Engineering Consultants Ltd. GRAIN SIZE DISTRIBUTION PERCENTAGE PASSING
SIEVE
Project: SRK 2004 Testing Services
40
Project Number: 1780108
25
Client: SRK Consulting
20
Attention: Mr. Dylan MacGregor, Project Manager
16
Date Tested: May 4, 2004
12.5
Borehole Number: SRK 46
10
Depth:
5
100
2.5
100
12.3 - 13.8 m
Sample Number: Lab Number:
3560-3
1.25
96
Soil Description:
SAND, trace silt
0.63
82
Natural Moisture Content: 20.0%
0.315
52
Remarks:
0.16
18
0.08
7.7
NP
CLAY
SAND
SILT FINE
GRAVEL
MEDIUM
COARSE
FINE
COARSE
SIEVE SIZES 200
100
100
60
40 30 20 16
10 8
4
3/8 1/2 3/4 1 11/2 2
90 80
PERCENT SMALLER
70 60 50 40 30 20 10 0 .0005 .001
.002
.005
.01
.02
.05
.1
.2
.5
1
2
5
10
GRAIN SIZE (millimeters)
Reviewed By: Data presented hereon is for the sole use of the stipulated client. EBA is not responsible, nor can be held liable, for use made of this report by any other party, with or without the knowledge of EBA
P.Eng.
The testing services reported herein have been performed by an EBA technician to recognized Industry standards, unless otherwise noted, No other warranty is made. These data do not include or represent any interpretation or opinion of specification compliance or material suitability. Should engineering interoperation be required, EBA will provide it upon written request.
20
50
3
EBA Engineering Consultants Ltd. GRAIN SIZE DISTRIBUTION PERCENTAGE PASSING
SIEVE
Project: SRK 2004 Testing Services
40
Project Number: 1780108
25
Client:
20
SRK Consulting
Attention: Mr. Dylan MacGregor, Project Manager
16
Date Tested: May 4 - May 6,2004
12.5
Borehole Number: SRK 47
10
Depth:
5
100
Sample Number: n/a
2.5
100
Lab Number:
3560-1
1.25
100
Soil Description:
Clayey SILT, trace sand, CL
0.63
100
Natural Moisture Content: 37.2%
0.315
99
Remarks:
0.16
99
0.08
93.7
2.1 - 3.6 m
LL=34%, PL=18%, PI=16%
CLAY
SAND
SILT FINE
GRAVEL
MEDIUM
COARSE
FINE
COARSE
SIEVE SIZES 200
100
100
60
40 30 20 16
10 8
4
3/8 1/2 3/4 1 11/2 2
90 80
PERCENT SMALLER
70 60 50 40 30 20 10 0 .0005 .001
.002
.005
.01
.02
.05
.1
.2
.5
1
2
5
10
GRAIN SIZE (millimeters)
Reviewed By: Data presented hereon is for the sole use of the stipulated client. EBA is not responsible, nor can be held liable, for use made of this report by any other party, with or without the knowledge of EBA
P.Eng.
The testing services reported herein have been performed by an EBA technician to recognized Industry standards, unless otherwise noted, No other warranty is made. These data do not include or represent any interpretation or opinion of specification compliance or material suitability. Should engineering interoperation be required, EBA will provide it upon written request.
20
50
3
EBA Engineering Consultants Ltd. GRAIN SIZE DISTRIBUTION PERCENTAGE PASSING
SIEVE
Project: SRK 2004 Testing Services
40
Project Number: 1780108
25
Client: SRK Consulting
20
Attention: Mr. Dylan MacGregor, Project Manager
16
Date Tested: May 4 - May 6, 2004
12.5
Borehole Number: SRK 49
10
Depth:
5
100
Sample Number: n/a
2.5
100
Lab Number:
3560-5
1.25
100
Soil Description:
Sandy, clayey SILT, CL
0.63
99
Natural Moisture Content: 32.6%
0.315
99
Remarks:
0.16
97
0.08
76.7
5.1 - 8.1 m
LL=22%, PL=15%, PI=7%
CLAY
SAND
SILT FINE
GRAVEL
MEDIUM
COARSE
FINE
COARSE
SIEVE SIZES 200
100
100
60
40 30
20 16
10 8
.5
1
2
4
3/8 1/2 3/4 1
11/2 2
90 80
PERCENT SMALLER
70 60 50 40 30 20 10 0 .0005
.001
.002
.005
.01
.02
.05
.1
.2
5
10
GRAIN SIZE (millimeters)
Reviewed By: Data presented hereon is for the sole use of the stipulated client. EBA is not responsible, nor can be held liable, for use made of this report by any other party, with or without the knowledge of EBA
P.Eng.
The testing services reported herein have been performed by an EBA technician to recognized Industry standards, unless otherwise noted, No other warranty is made. These data do not include or represent any interpretation or opinion of specification compliance or material suitability. Should engineering interoperation be required, EBA will provide it upon written request.
20
50
3
EBA Engineering Consultants Ltd. GRAIN SIZE DISTRIBUTION PERCENTAGE PASSING
SIEVE
Project: SRK 2004 Testing Services
40
Project Number: 1780108
25
Client:
20
SRK Consulting
Attention: Mr. Dylan MacGregor, Project Manager
16
Date Tested: May 4 - May 6, 2004
12.5
Borehole Number: SRK 49
10
Depth:
5
14.1 - 17.1 m
Sample Number: n/a
2.5
100
Lab Number:
3560-6
1.25
100
Soil Description:
SILT and CLAY, trace sand, CL
0.63
100
Natural Moisture Content: 58.6%
0.315
100
Remarks:
0.16
99
0.08
96.4
LL=38%, PL=22%, PI=16%
CLAY
SAND
SILT FINE
GRAVEL
MEDIUM
COARSE
FINE
COARSE
SIEVE SIZES 200
100
100
60
40 30 20 16
10 8
4
3/8 1/2 3/4 1 11/2 2
90 80
PERCENT SMALLER
70 60 50 40 30 20 10 0 .0005 .001
.002
.005
.01
.02
.05
.1
.2
.5
1
2
5
10
GRAIN SIZE (millimeters)
Reviewed By: Data presented hereon is for the sole use of the stipulated client. EBA is not responsible, nor can be held liable, for use made of this report by any other party, with or without the knowledge of EBA
P.Eng.
The testing services reported herein have been performed by an EBA technician to recognized Industry standards, unless otherwise noted, No other warranty is made. These data do not include or represent any interpretation or opinion of specification compliance or material suitability. Should engineering interoperation be required, EBA will provide it upon written request.
20
50
3
Appendix E Phase II Foundation Investigation (SRK 2005)
Phase II Foundation Investigation Proposed Roberts Bay Jetty Location Doris North Project, Nunavut, Canada
Prepared for
Miramar Hope Bay Limited
Prepared by
May 2005
Phase II Foundation Investigation: Proposed Roberts Bay Jetty Location Doris North Project, Nunavut, Canada
Miramar Hope Bay Limited Suite 300, 889 Harbourside Drive North Vancouver, B.C. V7P 3S1
SRK Consulting (Canada) Inc. Suite 800, 1066 West Hastings Street Vancouver, B.C. V6E 3X2
Tel: 604.681.4196 Fax: 604.687.5532 E-mail:
[email protected] Web site: www.srk.com
SRK Project Number 1CM014.04-0110
May 2005
Authors Dylan MacGregor, M.A.Sc., GIT Peter Mikes, EIT
Reviewed by Maritz Rykaart, Ph.D, P.Eng.
SRK Consulting Phase II Foundation Investigation Proposed Roberts Bay Jetty Location
Page i
Table of Contents 1 Introduction .................................................................................................................. 1 2 Field Program............................................................................................................... 1 2.1 Methods .............................................................................................................................. 1 2.2 Boring locations................................................................................................................... 2
3 Results .......................................................................................................................... 3 4 References.................................................................................................................... 6
List of Tables Table 1: Summary of Undrained Shear Strengths ........................................................................... 3
List of Figures Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6: Figure 7: Figure 8: Figure 9:
Hope Bay Doris North Project Site Map Proposed Jetty In-Situ Testing Locations Undrained Shear Strength Profile – Boring #1 Undrained Shear Strength Profile – Boring #2 Undrained Shear Strength Profile – Boring #3 Undrained Shear Strength Profile – Boring #4 Undrained Shear Strength Profile – Boring #5 Undrained Shear Strength Profile – Boring #6 Undrained Shear Strength Profiles
List of Appendices Appendix 1:
DBM/spk
Detailed Calculations
2005.Jetty.Investigation.report.1CM014.004.dbm.rev02.doc, May. 26, 05, 3:17 PM
May 2005
SRK Consulting Phase II Foundation Investigation Proposed Roberts Bay Jetty Location
1
Page 1
Introduction As part of the ongoing process of obtaining site information upon which surface infrastructure designs can be based for the Doris North Project, MHBL contracted SRK to undertake a second phase foundation investigation at the site of the proposed jetty at Roberts Bay (Figure 1) during April 2005. The primary objective of this field program was to collect in-situ measurements of undrained shear strength for the fine-grained soils identified in the jetty footprint during 2004 drilling (SRK 2004). This report presents the results of the in-situ testing of the fine-grained sediment within the proposed jetty footprint. Included is a description of the field investigation and a summary of the in-situ testing results.
2
Field Program The in-situ testing was carried out April 13 to 15 and April 17, 2005, by SRK staff Dylan MacGregor and Peter Mikes, with assistance by Anastasia Ledwon of MHBL. Six borings were completed, with strength testing completed at five to six discrete depths at each boring location.
2.1
Methods Testing of undrained strength of the jetty foundation soils was accomplished using a Nilcon vane shear apparatus that was rented from Roctest Telemac of Montreal. This apparatus consisted of a boring rig capable of driving a vane into the soil by means of a string of 1.0 m rods, and a torque recording head that rotated the rods and recorded the torque required for rotation. The shear vane was fixed to the end of the rod string, and test depth was gauged from the number and the position of the rods. To access the marine sediments located within the jetty footprint, 0.15m diameter holes were augered through the sea ice. A tent was initially set up over the holes to provide a degree of shelter, as the testing apparatus does not function properly under cold or windy conditions. A survival shelter on skids was used at the final four locations due to the poor performance of the tent under windy conditions. At each boring location, the length of auger required to penetrate the sea ice was recorded. The vane and rod assembly was then inserted into the auger hole, and lowered until the vane contacted the sediment. The total depth of water (liquid and frozen) was recorded, and the vane was advanced to the depth of the initial test. Once the vane was positioned at the desired depth, torque was applied to the rods via a torquerecording head mounted on top of the boring rig. The rods were rotated at a constant rate of
DBM/spk
2005.Jetty.Investigation.report.1CM014.004.dbm.rev02.doc, May. 26, 05, 3:17 PM
May 2005
SRK Consulting Phase II Foundation Investigation Proposed Roberts Bay Jetty Location
Page 2
approximately 6° per minute, and the developed torque was recorded on pressure-sensitive paper disks by means of a metal recording arm that rotated with the rods. At each depth, an initial test was conducted where the torque developed prior to failure of the soil was recorded (the peak torque), as well as the torque required to turn the rods following failure (the residual torque). The soil at the test depth was then remoulded by manually turning the rods 20 times with a pipe wrench, and the torque required to turn the vane in this remoulded soil (the remoulded torque) was recorded. As part of this second test, a slip coupling mounted immediately above the vane allowed a limited rotation of the rods only, without rotation of the vane. This portion of the test recorded the torque required to turn only the rods (the rod rotation torque), and allowed the removal of rod resistance as part of data processing. A more detailed description of the method is found in Roctest (2002).
2.2
Boring locations In-situ testing was carried out at six locations, as shown in Figure 2. These locations are situated within the footprint of the jetty’s northern terminus. Foundation testing focussed on this area because this portion of the footprint will receive the largest thickness of rock fill during construction, and as such is the most sensitive to excessive loading. Drilling in 2004 indicated that the shallow sediment was of a common soil type between the tested area and the shoreline to the south (SRK 2004). At each boring location, vane shear tests were taken at 5 or 6 depths, nominally every meter from the sediment surface to a depth of 5m. The near-surface sediment has the greatest risk of failure due to loading during the construction phase, and consequently testing focussed on this portion of the deposit.
DBM/spk
2005.Jetty.Investigation.report.1CM014.004.dbm.rev02.doc, May. 26, 05, 3:17 PM
May 2005
SRK Consulting Phase II Foundation Investigation Proposed Roberts Bay Jetty Location
3
Page 3
Results The calculated undrained peak, residual and remoulded shear strengths are summarized in Table 1 below and strength profiles for each boring are shown in Figures 3 though 8 with a compilation of all profiles for comparison shown in Figure 9. Table 1: Summary of Undrained Shear Strengths Hole ID
1
2
3
4
5
6
Boring Coordinates1 E
N
432,514
432,539
432,525
432,543
432,528
432,516
7,563,338
7,563,351
7,563,343
7,563,339
7,563,333
7,563,329
Test Depth (m)
Peak Strength (kPa)
Residual Strength (kPa)
Remoulded Strength (kPa)
Sensitivity (Peak/Remoulded)
0.5 1 2 3 4
16.69 13.31 14.37 20.91 25.88
7.24 6.18 7.45 8.61 11.62
2.85 0.63 2.80 4.07 3.96
5.85 21.13 5.13 5.14 6.53
5
27.25
10.35
4.17
6.53
1 2 3 4
16.48 15.90 18.49 17.38
8.98 5.65 12.68 8.40
3.91 3.06 4.23 3.38
4.22 5.19 4.38 5.14
5
20.49
11.62
2.90
7.05
1 2 3 4
19.91 17.11 21.97 22.08
8.19 7.55 8.56 9.35
4.44 3.80 3.27 3.22
4.49 4.50 6.71 6.85
5
24.08
9.72
2.43
9.91
1.25 2.25 3.25 4.25
15.32 16.11 26.72 28.10
4.65 6.23 8.77 10.19
4.01 3.17 4.07 3.38
3.82 5.08 6.57 8.31
5.25
24.14
9.24
1.85
13.06
1.25 2.25 3.25 4.25
19.86 16.21 26.67 26.88
9.51 6.34 11.14 9.35
3.96 2.59 4.33 3.75
5.01 6.27 6.16 7.17
5.25
25.09
11.04
2.64
9.50
1 2.5 3.5 4.5
16.43 16.48 25.35 22.92
8.61 5.92 9.72 8.13
2.38 3.75 4.28 2.27
6.91 4.39 5.93 10.09
5.5
14.42
4.65
1.00
14.37
Maximum Value
28.10
12.68
4.44
21.13
Minimum Value
13.31
4.65
0.63
3.82
Average Value
20.42
8.57
3.24
7.14
1. UTM projection NAD83 Zone 13
DBM/spk
2005.Jetty.Investigation.report.1CM014.004.dbm.rev02.doc, May. 26, 05, 3:17 PM
May 2005
SRK Consulting Phase II Foundation Investigation Proposed Roberts Bay Jetty Location
Page 4
The strength profiles are generally consistent for each boring with the top 2 to 3 meters of marine sediment being distinctively weaker than the lower portion of the profiles. The peak strength values show results typical of a soft to very soft soil, ranging from 13.31 to 28.10 kPa with an average value of 20.42 kPa. The residual strengths average to be 42% of the peak strength and are generally consistent as a percentage of the peak strength with depth. The soil sensitivity, the ratio of the peak undisturbed undrained shear strength to the remoulded undrained shear strength has an average value of 7.14 and was found to generally increase with depth. The sensitivity of the soils ranged from a medium sensitive soil close to the surface, to an extra sensitive soil on the bottom end of the profile.
DBM/spk
2005.Jetty.Investigation.report.1CM014.004.dbm.rev02.doc, May. 26, 05, 3:17 PM
May 2005
SRK Consulting Phase II Foundation Investigation Proposed Roberts Bay Jetty Location
Page 5
This report, “Phase II Foundation Investigation Proposed Roberts Bay Jetty Location, Doris North Project, Nunavut, Canada”, has been prepared by SRK Consulting (Canada) Inc.
Prepared by:
Dylan MacGregor, M.A.Sc., G.I.T.
Peter Mikes, E.I.T.
Reviewed by:
Maritz Rykaart, Ph.D., P.Eng. Senior Geotechnical Engineer
DBM/spk
2005.Jetty.Investigation.report.1CM014.004.dbm.rev02.doc, May. 26, 05, 3:17 PM
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SRK Consulting Phase II Foundation Investigation Proposed Roberts Bay Jetty Location
4
Page 6
References Roctest. 2002. Instruction Manual: Vane Borer Model M-1000. Roctest Limited, Montreal, QC. SRK Consulting, 2004. Phase I Foundation Investigation, Proposed Roberts bay Jetty Location, Doris North Project, Nunavut, Canada. Report submitted to Miramar Hope Bay Limited, April 2004.
DBM/spk
2005.Jetty.Investigation.report.1CM014.004.dbm.rev02.doc, May. 26, 05, 3:17 PM
May 2005
Figures
Figs 3-4-5-6-7-8-9_ Vane Borer Data_ck.xls/Fig 3-B#1
Undrained Shear Strength (kPa) 0.0
5.0
10.0
15.0
20.0
25.0
30.0
0.0
1.0
Depth (m)
2.0
Peak Strength (kPa) Residual Strength (kPa) Remoulded Strength (kPa) 3.0
4.0
5.0
6.0 DORIS NORTH PROJECT Phase II Jetty Foundation Investigation
Undrained Shear Strength Profile Boring #1
MIRAMAR HOPE BAY LIMITED
PROJECT
DATE
1CM014.004
May 2005
APPROVED
EMR
FIGURE
3
Figs 3-4-5-6-7-8-9_ Vane Borer Data_ck.xls/Fig 4-B#2
Undrained Shear Strength (kPa) 0.0
5.0
10.0
15.0
20.0
25.0
0.0
1.0
Depth (m)
2.0 Peak Strength (kPa) Residual Strength (kPa) Remoulded Strength (kPa) 3.0
4.0
5.0
6.0 DORIS NORTH PROJECT Phase II Jetty Foundation Investigation
Undrained Shear Strength Profile Boring #2
MIRAMAR HOPE BAY LIMITED
PROJECT
DATE
APPROVED
1CM014.004
MAY 2005
E.M.R.
FIGURE
4
Figs 3-4-5-6-7-8-9_ Vane Borer Data_ck.xls/Fig 5-B#3
Undrained Shear Strength (kPa) 0.0
5.0
10.0
15.0
20.0
25.0
30.0
0.0
1.0
Depth (m)
2.0 Peak Strength (kPa) Residual Strength (kPa) Remoulded Strength (kPa) 3.0
4.0
5.0
6.0 DORIS NORTH PROJECT Phase II Jetty Foundation Investigation
Undrained Shear Strength Profile Boring #3
MIRAMAR HOPE BAY LIMITED
PROJECT
DATE
1CM014.004
May 2005
APPROVED
EMR
FIGURE
5
Figs 3-4-5-6-7-8-9_ Vane Borer Data_ck.xls/Fig 6-B#4
Undrained Shear Strength (kPa) 0.0
5.0
10.0
15.0
20.0
25.0
30.0
0.0
1.0
Depth (m)
2.0 Peak Strength (kPa) Residual Strength (kPa) Remoulded Strength (kPa) 3.0
4.0
5.0
6.0 DORIS NORTH PROJECT Phase II Jetty Foundation Investigation
Undrained Shear Strength Profile Boring #4
MIRAMAR HOPE BAY LIMITED
PROJECT
DATE
1CM014.004
May 2005
APPROVED
EMR
FIGURE
6
Figs 3-4-5-6-7-8-9_ Vane Borer Data_ck.xls/Fig 7-B#5
Undrained Shear Strength (kPa) 0.0
5.0
10.0
15.0
20.0
25.0
30.0
0.0
1.0
Depth (m)
2.0 Peak Strength (kPa) Residual Strength (kPa) Remoulded Strength (kPa) 3.0
4.0
5.0
6.0 DORIS NORTH PROJECT Phase II Jetty Foundation Investigation
Undrained Shear Strength Profile Boring #5
MIRAMAR HOPE BAY LIMITED
PROJECT
DATE
1CM014.004
May 2005
APPROVED
EMR
FIGURE
7
Figs 3-4-5-6-7-8-9_ Vane Borer Data_ck.xls/Fig 8-B#6
Undrained Shear Strength (kPa) 0.0
5.0
10.0
15.0
20.0
25.0
30.0
0.0
1.0
2.0
Depth (m)
Peak Strength (kPa) Residual Strength (kPa) Remoulded Strength (kPa)
3.0
4.0
5.0
6.0 DORIS NORTH PROJECT Phase II Jetty Foundation Investigation
Undrained Shear Strength Profile Boring #6
MIRAMAR HOPE BAY LIMITED
PROJECT
DATE
1CM014.004
May 2005
APPROVED
EMR
FIGURE
8
Figs 3-4-5-6-7-8-9_ Vane Borer Data_ck.xls/Fig 9-All Data Graph
Undrained Shear Strength (kPa) 0.0
5.0
10.0
15.0
20.0
25.0
30.0
0.0
Boring 1 - Peak
1.0
Boring 1 - Residual Boring 1 - Remolded Boring 2 - Peak Boring 2 - Residual Boring 2 - Remolded
2.0
Boring 3 - Peak Boring 3 - Residual
Depth (m)
Boring 3 - Remolded Boring 4 - Peak Boring 4 - Residual
3.0
Boring 4 - Remolded Boring 5 - Peak Boring 5 - Residual Boring 5 - Remolded Boring 6 - Peak
4.0
Boring 6 Residual Boring 6 - Remolded
5.0
6.0 DORIS NORTH PROJECT Phase II Jetty Foundation Investigation
Undrained Shear Strength Profiles Combined
MIRAMAR HOPE BAY LIMITED
PROJECT
DATE
1CM014.004
MAY 2005
APPROVED
EMR
FIGURE
9
Appendices
Appendix 1 Detailed Calculations
M a K Mf
Symbols Torque (Kg m) Distance from zero torque reference line (cm) Calibration constant = 1.0563 kg.m/cm Torque required to rotate rods
Ms
Torque required to rotate rods + vane at yielding
Mv Su
Torque required to rotate vane at yielding (Mf - Ms) Shear strength (kg/cm2)
C
Vane form constant (8x17.2cm) = 0.05 m-1cm-2
Residual
Calibration constant, K (kg·m/cm): Vane form constant, C (10-2 x cm-3):
Boring # 1A 1B 1C 1D 1E 1F 2A 2B 2C 2D 2E 3A 3B 3C 3D 3E 4A 4B 4C 4D 4E 5A 5B 5C 5D 5E 6A 6B 6C 6D 6E
Depth (m) 0.5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1.25 2.25 3.25 4.25 5.25 1.25 2.25 3.25 4.25 5.25 1 2.5 3.5 4.5 5.5
Equations: Mv = K*(as-af) Su = Mv * C * 100
1.0563 0.05
Undisturbed Peak Strength af (cm) as (cm) Mv (kg·m) Su (kPa) 0.02 0.13 0.18 0.24 0.1 0.51 0.1 0.14 0.30 0.32 0.30 0.07 0.19 0.39 0.41 0.42 0.8 0.2 0.44 0.29 0.42 0.25 0.1 0.16 0.41 0.2 0.13 0.3 0.40 0.58 0.8
3.18 2.65 2.9 4.2 5 5.67 3.22 3.15 3.80 3.61 4.18 3.84 3.43 4.55 4.59 4.98 3.7 3.25 5.5 5.61 4.99 4.01 3.17 5.21 5.5 4.95 3.24 3.42 5.20 4.92 3.53
3.34 2.66 2.87 4.18 5.18 5.45 3.30 3.18 3.70 3.48 4.10 3.98 3.42 4.39 4.42 4.82 3.06 3.22 5.34 5.62 4.83 3.97 3.24 5.33 5.38 5.02 3.29 3.30 5.07 4.58 2.88
16.69 13.31 14.37 20.91 25.88 27.25 16.48 15.90 18.49 17.38 20.49 19.91 17.11 21.97 22.08 24.08 15.32 16.11 26.72 28.10 24.14 19.86 16.21 26.67 26.88 25.09 16.43 16.48 25.35 22.92 14.42
Residual Strength as (cm) Mv (kg·m) Su (kPa) 1.39 1.30 1.59 1.87 2.30 2.47 1.80 1.21 2.70 1.91 2.50 1.62 1.62 2.01 2.18 2.26 1.68 1.38 2.10 2.22 2.17 2.05 1.30 2.27 2.18 2.29 1.76 1.42 2.24 2.12 1.68
1.45 1.24 1.49 1.72 2.32 2.07 1.80 1.13 2.54 1.68 2.32 1.64 1.51 1.71 1.87 1.94 0.93 1.25 1.75 2.04 1.85 1.90 1.27 2.23 1.87 2.21 1.72 1.18 1.94 1.63 0.93
7.24 6.18 7.45 8.61 11.62 10.35 8.98 5.65 12.68 8.40 11.62 8.19 7.55 8.56 9.35 9.72 4.65 6.23 8.77 10.19 9.24 9.51 6.34 11.14 9.35 11.04 8.61 5.92 9.72 8.13 4.65
af (cm) 0 0 0.09 0.22 0.38 0.51 0.05 0.12 0.20 0.25 0.38 0.05 0.19 0.3 0.41 0.42 0.05 0.21 0.28 0.47 0.55 0.05 0.22 0.23 0.27 0.5 0.05 0.21 0.21 0.38 0.5
Remolded as (cm) Mv (kg·m) 0.54 0.12 0.62 0.99 1.13 1.30 0.79 0.70 1.00 0.89 0.93 0.89 0.91 0.92 1.02 0.88 0.81 0.81 1.05 1.11 0.90 0.8 0.71 1.05 0.98 1 0.5 0.92 1.02 0.81 0.69
0.57 0.13 0.56 0.81 0.79 0.83 0.78 0.61 0.85 0.68 0.58 0.89 0.76 0.65 0.64 0.49 0.80 0.63 0.81 0.68 0.37 0.79 0.52 0.87 0.75 0.53 0.48 0.75 0.86 0.45 0.20
Su (kPa) 2.85 0.63 2.80 4.07 3.96 4.17 3.91 3.06 4.23 3.38 2.90 4.44 3.80 3.27 3.22 2.43 4.01 3.17 4.07 3.38 1.85 3.96 2.59 4.33 3.75 2.64 2.38 3.75 4.28 2.27 1.00
Comments No extra wieght on frame No extra wieght on frame Extra wieght: 325 lbs Extra wieght: 180 lbs Extra wieght: 325 lbs; difficult to push down relative to previous advance Easy to drive vane down Easy to drive vane down Difficult to advance - 2 people on frame (325lbs) Difficult to advance - 2 people on frame (325lbs) Difficult to advance - 2 people on frame (325lbs) Very easy to advance - pushed down by hand. Easy to push down - pushed by hand. (2 people) Difficult to advance - 2 people on frame (325lbs) Difficult to advance - 2 people on frame (325lbs) Difficult to advance - 2 people on frame (325lbs) Difficult to advance - 2 people on frame (415lbs) Easy to push. Moderately difficult to drive Difficult to advance - 2 people on frame (415lbs) Difficult to advance - 2 people on frame (415lbs) Easy to drive into sediment Easy to drive into sediment Moderately difficult to drive Moderately difficult to drive Moderately difficult to drive Easy to advance Moderately difficult to drive Moderately difficult to drive Moderately difficult to drive Difficult to advance - 2 people on frame (415lbs)
Appendix F Technical Memorandum Outlining Preliminary Jetty Design Calculations
SRK Consulting (Canada) Inc. Suite 800 – 1066 West Hastings Street Vancouver, B.C. V6E 3X2 Canada
[email protected] www.srk.com
Tel: 604.681.4196 Fax: 604.687.5532
Technical Memorandum To:
Brian Labadie - MHBL
Date:
September 14, 2005
cc:
Project File
From:
Maritz Rykaart, Ben Wickland
Subject:
Preliminary Jetty Design Calculations
Project #:
1CM014.006
1
Introduction This technical memorandum documents design calculations and assumptions for the geotechnical aspects of the proposed continuous rock fill jetty in Roberts Bay, Hope Bay, Nunavut, Canada. This jetty will be part of the development infrastructure for the proposed Doris North Project, a small gold mine being developed by Miramar Hope Bay Limited. Complete details and drawings of the proposed jetty are documented in the following report; SRK Consulting (Canada) Inc. 2005. Preliminary Jetty Design, Doris North Project, Hope Bay, Nunavut, Canada. Technical report submitted to Miramar Hope Bay Limited, Project No. 1CM014.006, October 2005. This design is preliminary in nature, and is intended to be used to confirm general feasibility of the concept proposed, and allow for cost estimation to ±15% accuracy.
2
Preliminary Design
2.1
Design Approach The continuous rock fill jetty will be constructed on soft marine sediments. It is therefore necessary to confirm that the load applied by the jetty will be less than the allowable (ultimate) bearing capacity of the marine sediments. For the purpose of this design it is reasonable to assume that the base of the rock fill jetty is a shallow foundation (Holtz and Kovacs 1981).
2.2
Data Sources Geotechnical data for the jetty foundation material has been documented in the Preliminary Jetty Design Report mentioned in Section 1 of this technical memorandum. This data includes drill holes, in-situ vane shear testing and laboratory foundation indicator testing. The data is deemed adequate to conduct a preliminary design for the jetty.
2.3
Applied Loads
2.3.1
Dead Loads The limiting case for the proposed jetty geometry is described by a cross section through the jetty head. This jetty head consists of a 25 m wide roadway crown over a 6.5 m deep fill with side slopes of 1.2:1. Under this scenario, the base of the foundation is 40.8 m wide, and the water level is 1.5 m below the roadway.
BW/EMR
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For a 1 m deep section through the jetty head fill, the volumes, unit weights, and total dead load for the geometry described above are included in Table 1. Table 1. Jetty head section volumes, unit weights, and loads. Section Volume m3 Unit Wt. (kN/m3)
Load (kN)
Unsaturated upper fill
40.2
19.62
789
Saturated lower fill
173.0
9.81 (submerged)
1,697
Total fill
213.2
2,486
Thus, for a total area of 40.2 m2, the applied load of 2,486 kN, due to the weight of the fill, results in an applied stress, qa, of 61.8 kPa over the area of the footing. 2.3.2
Live Loads Live loads on the jetty include the traffic of loaders, as well as the action of ice, wind, and snow. The action of ice, wind and snow are not considered here. The total load applied by a Komastsu WA500-3 Wheeled Loader (the largest equipment to be used) with a fully laden shipping container is approximately 48,100 kg. Over a 1 m deep section of the jetty head, the applied load is equivalent to an additional increase in applied stress, qa, of 1.2 kPa.
2.3.3
Total Load The total load exerted by the jetty on the marine foundation is thus the sum of the live and the dead load, i.e. 61.8 + 1.2 = 63 kPa.
2.4
Bearing Capacity Nilcon vane shear test results for the upper 5 m of marine sediment at the jetty head location are summarized in Table 2. Table 2. Nilcon vane shear test results for proposed jetty head location. Peak (kPa) Residual (kPa) Remoulded (kPa) Maximum
28.1
12.7
4.4
Minimum
13.3
4.7
0.6
Average
20.4
8.6
3.2
The bearing capacity of the sediment was calculated on the basis of peak undrained shear strength of 15 kPa. The average plasticity index of CL samples taken from the proposed jetty location, and from the 1997 investigation in the area (EBA 1997) was 17.5%, and no vane shear correction was applied to field values. For undrained loading at the surface of the marine sediment, the ultimate bearing capacity equation reduces to: qu = NcCu where, qu is ultimate bearing capacity, Nc is a bearing capacity coefficient, and Cu is the undrained shear strength. The value of Nc for a soft sediment varies to a maximum of 5.14. Accordingly, the ultimate bearing capacity, qu, of the sediment is 77.1 kPa. BW/EMR
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2.5
Page 3 of 5
Bearing Capacity Factor of Safety The factor of safety is calculated as follows: F.S. = qu/qa = 77.1 kPa / 63 kPa = 1.22
2.6
Consolidation Settlement
2.6.1
Total Settlement The proposed jetty will undergo settlement due to the consolidation of the underlying marine sediment. Samples were not tested for compressibility, but total settlements and time to consolidation are estimated here based on sample void content as determined from saturated water content, the depth of the sediment layer, and assumed values of compression index and coefficient of consolidation. Values of parameters used for the calculation of total settlement are included in Table 3. Table 3. Design values for consolidation calculations. Component
Value
Thickness of marine sediment layer
13 m
Saturated unit weight of marine sediment
18 kN/m3
Initial effective stress at midpoint of the layer
53.2 kPa
Initial void ratio
1.27
Compression Index
0.25 to 0.5 (assumed)
Applied stress
62 kPa
Coefficient of consolidation
10 m2/year (assumed)
Assuming an increase in effective stress equal to the dead load of 61.8 kPa, the midpoint of the profile will undergo a change in effective stress from 53.2 kPa to 115.2 kPa. The total expected settlement is estimated to be approximately 0.5 m to 1.0 m. 2.6.2
Time Rate of Consolidation Estimates of time of consolidation indicate up to 0.15 m settlement after one year, and up to 0.3 m after 5 years. The actual rates of settlement may vary considerably from estimates. Rates of consolidation are estimated from coefficient of consolidation. The coefficient of consolidation of 10 m2/year listed in Table 3 was approximated from the average liquid limit of near 40% and Figure 9.10, page 404, Holtz and Kovacs (1981). Time to consolidation is highly dependent on the hydraulic conductivity of the sediment, which was not measured. The drilling program observed some sandier sediments, which will have higher hydraulic conductivity than clay rich portions. The presence of sandy layers may increase the rate of consolidation.
3
Design Options Alternative geometries and the effect of including geosynthetic re-enforcement of the base of the jetty fill were examined for effect on applied load qa and factor of safety, F.S.
BW/EMR
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3.1
Page 4 of 5
Jetty Head Geometry Options for decreasing the pressure at the base of the jetty head fill include flattening the side slopes, and reducing the width of the fill. The variation in applied stress is illustrated in Table 4. The most conservative design includes a design profile with a 6 m roadway with 4:1 side slopes. Predicted loads are converted to factors of safety, F.S.’s, in Table 5. Table 4. Variation in applied stress, qa, due to changes in jetty head geometry. Top Width (m)
Side Slope (H:V)
25
15
10
6
1.2:1
61.2
55.6
51.1
46.1
2:1
55.6
50.0
46.1
42.0
3:1
51.1
46.1
42.7
39.6
4:1
48.2
43.6
40.8
38.2
Table 5. Factor of Safety for alternate jetty head geometries (excluding live loads).
3.2
Top Width (m)
Side Slope (H:V)
25
15
10
6
1.2:1
1.26
1.39
1.51
1.67
2:1
1.39
1.54
1.67
1.84
3:1
1.51
1.67
1.80
1.95
4:1
1.60
1.77
1.89
2.02
Geosynthetic Re-Enforcement The use of geosynthetic (geotextile and geogrid) re-enforcement at the base of the fill was investigated for effect on bearing capacity (Koerner 2005). Two suppliers were also contacted for information regarding the use of geosynthetics. Principle advantages to using a geosynthetic reenforcement at the base of the jetty fill include: • • • •
Prevent rock fill from sinking upon initial placement during construction Reduction of differential settlements Even distribution of stress over marine sediment – allowing use of Nc = 5.14 Prevent movement of fines into overlying coarse layers
The soft marine sediments at the proposed jetty location may fail during construction if the ultimate bearing capacity is exceeded. With time, the sediments will consolidate, and the allowable load will increase. However, localized loading may cause a failure, and a geosynthetic re-enforced pad will help reduce the potential for failure. A possible re-enforcement configuration over the base of the jetty fill includes a multiple layer structure of three to four layers of bi-axial geogrid, separated by 0.6 m of rock fill passing 30 cm. The jetty embankment fill may be constructed directly on top of the re-enforced layers. BW/EMR
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Case studies where geosynthetics has been used for this type of application are listed on the web site of one of the suppliers (www.tenax.net/geosynthetics/case_history). SRK is not aware of any case study of geosynthetic re-enforced pad constructed in an arctic environment. However, geosynthetics are commonly used in conventional applications in the arctic (liners, ponds, etc.), and therefore there is no reason to believe that this application would not be feasible. This statement is supported by the suppliers that was contacted, that are prepared to guarantee their product for this application in the arctic.
4
Recommendations for Further Work Based on the results of this preliminary design, it is evident that a jetty can be constructed as planned. Prior to conducting the detailed design it would be beneficial to conduct another field investigation in the jetty foundation sediments, specifically to collect undisturbed samples upon which triaxial shear testing and consolidation testing can be done.
5
References EBA Engineering Consultants. 1997. Boston Gold Project Geotechnical Investigation Proposed Roberts Bay Port. Report Submitted to BHP World Minerals, October. Holtz, R.D., and Kovacs, W.D. 1981. An Introduction to Geotechnical Engineering. Prentice-Hall Inc. New Jersey, pp.733. Koerner, R.M. 2005. Designing with Geosynthetics, Fifth Edition, Pearson Prentice Hall, N.J., 796 pages.
BW/EMR
TechMemoJettyDesign_emr.doc, 10:52 AM, Oct. 3, 05
Appendix G Typical Geogrid Specifications
TENAX LBO SAMP
Type: 220 - 330 - 440 Bi-oriented geogrids
TENAX LBO SAMP are polypropylene geogrids especially designed for soil stabilization and reinforcement applications. The LBO SAMP geogrids are manufactured from a unique process of extrusion and biaxial orientation to enhance their tensile properties. TENAX LBO SAMP features consistently high tensile strength and modulus, excellent resistance to construction damages and environmental exposure. Furthermore, the geometry of the TENAX LBO SAMP allows strong mechanical interlock with the soil being reinforced.
Typical applications Base reinforcement; reduction of required structural fill; load distribution; reduction of mud pumping; subgrade stabilization; embankment stabilization; slope reinforcement; erosion control mattresses. PHYSICAL CHARACTERISTICS STRUCTURE MESH TYPE STANDARD COLOR POLYMER TYPE CARBON BLACK CONTENT
TEST METHOD
ISO 10320
DIMENSIONAL CHARACTERISTICS
TEST METHOD
ISO 9864
UNIT
LBO 220 SAMP
LBO 330 SAMP
LBO 440 SAMP
NOTES
mm mm g/m² m m m m³ kg
41 31 250 4.0 100 0.41 0.69 107.0
40 27 370 4.0 75 0.45 0.81 118.0
34 27 640 4.0 50 0.52 1.10 135.0
b,d b,d b b b b b b
LBO 220 SAMP
LBO 330 SAMP
LBO 440 SAMP
NOTES
TEST METHOD
UNIT
STRENGTH AT 2% STRAIN STRENGTH AT 5% STRAIN PEAK TENSILE STRENGTH YIELD POINT ELONGATION
ISO 10319 ISO 10319 ISO 10319 ISO 10319
kN/m kN/m kN/m %
NOTES: a) 95% lower confidence limit values, ISO 2602 b) Typical values c) Tests performed using extensometers d) MD: machine direction (longitudinal to the roll) TD: transverse direction (across roll width)
NOTES
BI-ORIENTED GEOGRIDS RECTANGULAR APERTURES BLACK POLYPROPYLENE 2.0% ROLLS IN POLYETHYLENE BAGS WITH I.D. LABEL
TECHNICAL CHARACTERISTICS
GE0 78.7 - E 02/04
DATA
ASTM D1603
PACKAGING
APERTURE SIZE MD APERTURE SIZE TD MASS PER UNIT AREA ROLL WIDTH ROLL LENGTH ROLL DIAMETER ROLL VOLUME GROSS ROLL WEIGHT
UNIT
MD
TD
MD
TD
MD
TD
7.0 14.0 20.0 11.0
7.0 14.0 20.0 10.0
10.5 21.0 30.0 11.0
10.5 21.0 30.0 10.0
14.0 28.0 40.0 11.0
15.0 30.0 40.0 11.0
b,c,d b,c,d a,c,d b,c,d
Typical Tensile Characteristics TENAX LBO SAMP
TENAX LBO SAMP 50
TENSILE STRENGTH, [kN/m]
50
45
45
40
40
C
35
A = TENAX LBO 220 SAMP B = TENAX LBO 330 SAMP C = TENAX LBO 440 SAMP
C
35 30
30
B
25 20
20
10
5
5
5
10
STRAIN, [%]
MD
A
15
10
0
B
25
A
15
0
GEOGRID TYPE:
TENSILE STRENGTH, [kN/m]
15
0
0
5
10
STRAIN, [%]
TD
The TENAX Laboratory has been created in 1980 and has been continuously improved with the purpose of assuring unequalled technical development of the products and accurate Quality Control, The TENAX Laboratory can perform mechanical, hydraulic and durability tests, according to the most important international standards like ISO, CEN, ASTM, DIN, BSI, UNI.
TENAX SpA Geosynthetics Division Via dell'Industria, 3 I-23897 Viganò (LC) ITALY Tel. (+39) 039.9219307 Fax (+39) 039.9219200 e-mail:
[email protected] Web Site: www.tenax.net
TENAX International B.V. Geosynthetics Division Via Ferruccio Pelli, 14 CH-6900 Lugano SWITZERLAND Tel. (+41) 091.9242485 Fax (+41) 091.9242489 e-mail:
[email protected] Web Site: www.tenax.net
15
