File: 13714 Proposed Comprehensive Development ......File: 13714 Proposed Comprehensive Development – Garibaldi Springs Golf Course, Squamish, BC Page 1 215 - 1200 West 73 Avenue

File: 13714 Proposed Comprehensive Development – Garibaldi Springs Golf Course, Squamish, BC Page 1

215 - 1200 West 73 Avenue

Vancouver, BC V6P 6G5

604-439-0922

Polygon Development Ltd. April 1, 2016 900 – 1333 West Broadway File: 13714 Vancouver, BC V6H 4C2 Attention: Mr. Kevin Shoemaker Re: Preliminary Geotechnical Investigation Report, Comprehensive Re-Development, Garibaldi Springs Golf Course, Squamish, BC 1.0 INTRODUCTION We understand that Polygon Development Ltd. is considering acquiring the Garibaldi Spring Golf Course property with the intention of re-developing a portion of the site with townhomes and/or apartments. The property has the legal address of Lot 4, Plan BCP 4573, District Lot 511, Section 11. The property is approximately 40 acres and is located east of Tantalus Road on the north end of Squamish. GeoPacific has been asked to carry out a geotechnical investigation of the property to help ascertain the underlying soil and groundwater conditions as requited to provide preliminary geotechnical recommendations which would be used to help guide the proposed development plan. We understand that at this time townhouses are being considered on the northern portion of the site as shown on the preliminary site plan prepared by Raymond Letkemen Architects Inc., dated March 21, 2016. Our investigation was focused on this, northern, portion of the property. The report presents the findings of our investigation and makes general preliminary geotechnical recommendations for the project. 2.0 SITE DESCRIPTION The site is 40 acres in area and contains a wide variety of terrain ranging from Squamish River flood plain deposits to mountain slopes. The site is located northeast of the existing Executive Suites Hotel and Resort located at 40900 Tantalus Road. The current elevation of the flat portion of the property within the valley bottom is about 7 m geodetic, which slightly rises moving towards the steep slopes along the east side of the site. The maximum elevation along the steep slopes on the property is about 45 m geodetic. The property was previously developed as a golf course. Much of the floodplain portion of the site is treed, with clearings made for fairways and ponds as part of the golf course development. The depths of the ponds are not known, however, we expect that they would be in the range of 3 to 4 m deep. We understand that the materials excavated from the ponds were deposited as fill on the fairways.


3.0 FIELD INVESTIGATION

GeoPacific carried out a site investigation on March 9, 2016. The investigation included augered test holes supplemented with cone penetration test (CPT) soundings. In total, 11 augured test holes were advanced to depths ranging from 2.2 to 7.6 m below site grades. Samples were collected from the auger flights for further classification and laboratory analysis. The test hole logs are included in Appendix A. Two CPT soundings were advanced to depths ranging from 6.95 to 7.1 m where refusal was met within the underlying compact to dense gravelly sand stratum. The electronic cone penetration tests (CPT) were conducted by hydraulically pushing the cone into the underlying soil strata. As the cone penetrometer was advanced, the tip resistance, sleeve friction, pore water pressure, and inclination were recorded at 5 cm intervals. Analysis of the CPT soundings provides an estimate of soil engineering properties, subsurface stratigraphy, and soil type behaviour characteristics. The stratigraphic interpretations were correlated with the findings from the augered test holes. The CPT sounding results are presented in Appendix B. The geotechnical parameters calculated from the CPT soundings, such as undrained shear strength and standard penetration N1(60) values, are presented in Appendix C. The approximate test hole locations are shown on our drawing, 13714-01, included following the text of this report. 4.0 SUBSURFACE CONDITIONS 4.1 General Comments Due to the size of the site the soil conditions were found to vary greatly across property. For ease of interpretation we have divided the property into different zones where distinctly different ground conditions were encountered. The recommendations presented in this report are specific to the zones described below. The aerial extent of the zones is shown on our drawings 13714 G-S1 included following the text of this report. 4.2 Soil Stratigraphy Zone A The soil conditions encountered in Zone A (test holes TH16-6, 7, 8 and CPT16-01 and CPT16-02) consist of a grass and topsoil cover underlain by a thin layer (0.05 m) of compact sand fill. The fill is underlain by a stiff silt deposit interbedded with loose fine sand and some organics (wood fibres) that becomes softer with depth. The silt is underlain by a layer of loose to compact sand with some fines to silty sand. A dense sand to sand and gravel deposit was identified below depths ranging from about 6.8 to 7 m. At TH16-08, silty sand and gravel fill was found overlying a layer of peat approximately 0.5 m below a depth of 1.5 m. Zone B The soil conditions encountered in Zone B (test holes TH16-9, 10, and 11) consist of a thin veneer of grass or topsoil over a thin layer (0.05 m) of compact sand fill. Below the fill is a dense to very dense glacial till comprised mostly of sand and gravel with some silt. At TH16-09 the glacial till is primarily silt with increasing sand and gravel content with depth. Bedrock is inferred at depths beyond those of our investigation and is exposed at the ground surface at some locations within this zone.


Zone C The soil conditions encountered in Zone C (test holes TH16-1, 2, 3, 4, and 5) generally consist of a grass and topsoil cover overlying fill and glacial till. The fill was variable and consists of either of sand, or sand and gravel, or silt. The fill is underlain by dense glacial till comprised of sand and gravel with trace to some cobbles, and occasional boulders. At TH16-03 wood fibres were encountered at depths between 1.5 m to 1.8 m and some wood debris was also encountered in TH16-04 indicating that these materials may be till-like fill and that other wood waste is likely. Auger refusal was met at depth of 4.4 m and 4.7 m at test holes TH16-02, and 04; bedrock is inferred at these depths. We understand that historically sand and gravel were mined from this area and therefore original site grades were well above existing grades as can be seen from the cut slope along the north side of the site. 4.3 Groundwater In the low lying portion of the site, within the Squamish River flood plain, the groundwater level was noted at depths ranging from 0.8 to 1.0 m below site grades. The groundwater level is expected vary as a result of seasonal variations in precipitation, and therefore we expect that it could rise up to near the ground surface in some areas. In the elevated portion of the site the groundwater table is expected to be well below site grades, however, some perched water could be encountered where more permeable soils overly less permeable soils or rock. 5.0 DISCUSSION 5.1 General The property is very large and therefore the soil conditions vary widely throughout the site. They range from very soft and very loose flood plain deposits of silt and sand and/or peat, to very dense lodgement till deposits overlying bedrock along the slopes. Therefore, a variety of considerations are required with respect to flood hazard, seismicity, and foundation design. The following presents a discussion on these considerations. 5.2 Flood Construction Level (FCL) The relatively flat western side of the golf course is within the Squamish River flood plain and thus a flood hazard exists. New construction would have to be set at an elevation such that any habitable space is located above a defined flood construction level (FCL). APEGBC, 2012, defines the FCL as the design flood level plus and allowance for freeboard. Normally we would recommend that a minimum freeboard of 0.3 m be applied to the flood surface elevation presented on the flood plain map. However, in the latest report prepared by KWL dated February 2nd, 2016, and provided for our review by the District of Squamish, it is recommend that no freeboard be applied to the values presented on the flood mapping due to the conservatisms whish were included in analysis. Therefore, the recommended FCL’s for this site would be in the range of 10.5 to 11.0 m. Current site grades in the flood plain portion of the site range from about 7 to 8 m. For construction where parking is proposed below the FCL level, and considering a top of slab to underside of floor joist height of 2.8 m, we estimate that about 0.7 m of fill would be required to achieve the lower slab level once a suitable underlying subgrade is established. Alternatively, the area below the FCL can be filled to meet the desired FCL.


5.3 Seismic Considerations Squamish is located in a seismically active zone and therefore seismicity should be considered in relation to the proposed development. Natural Resources Canada recommends a firm ground peak horizontal ground acceleration of 0.33g (where g is the acceleration due to gravity) at this location for the 1 in 2,475 seismic hazard. The soils within Zone A are considered susceptible to liquefaction and/or ground softening when the 1 in 2,475 year design seismic hazard is considered. The soils within Zones B and C are not considered susceptible to liquefaction triggering. The flat, low-lying, portion of site is underlain by loose sands and soft silts. It is generally accepted that loose to compact and saturated non-plastic silts are prone to liquefaction and/or strain softening during cyclic loading caused by large earthquakes. The strength reduction caused by soil liquefaction can cause conventional foundations to fail by punching into the liquefied soils. Once liquefaction is triggered, significant, permanent, vertical and horizontal movements may be experienced. In order to limit damage to townhomes should a large seismic event occur, we recommend that the townhomes be constructed on reinforced thickened slab foundations constructed over at least 1.5 m of dense granular structural fill compacted in place. Further recommendations are provided in Part 6 of this report. 5.4 Settlement Compressible silt containing wood fibres and organics was identified in both test holes conducted within the lower flood plain portion of the site (Zone A). Site filling and buildings will increase the stress within these deposits, resulting in consolidation and significant settlement at the ground surface. It is critical that most of the anticipated settlement takes place prior to installation of services, such as storm and sanitary, and prior to building construction. Due to the high compressibility of the underlying soils we recommend that the road and building sites be preloaded in advance of construction. Further recommendations are provided in Part 6 of this report. The filling and preloading of roads and adjacent lots should be done concurrently as the placement of large amounts of fill such as this will have interaction effects and will contribute to settlements on adjacent lots and the road. Consideration can be given to staging the preload provided an adequate overlap is provided. The soils within Zones B and C are not soft or prone to long term consolidation. We expect that conventional construction techniques would be used in these areas. 6.0 RECOMMENDATIONS 6.1 General The recommended site preparation varies depending on the soil conditions present within each of the zones. The soil condition vary from very soft and very loose deposits of silt and sand within the floodplain to very dense lodgement till deposits overlying bedrock along the slopes. Taking this into consideration, a variety of site preparation techniques will be required due to the variability in soil conditions that exist. The following presents general preliminary recommendations for the various areas of the site. Once the development plan is further advanced, additional test holes should be carried out at specific building locations as required to finalize our recommendations.


The areas referred to below are shown on our Drawing 13714-1 included following the text of this report. 6.2 Zone A – Flood Plain with No/Limited Peat Site preparation for the proposed building areas and roads includes removing all topsoil, peat, roots, variable fill or debris encountered to expose the underlying natural subgrade of silt or sand. Following stripping, clean well-graded pit run sand and gravel should be placed to the top of the finished ground floor slab level for buildings or pavement structure for roads. The fill should be placed at this level to a distance of at least 3 m outside of each of the proposed building areas. The fill should be compacted in place to a minimum of 95% Modified Proctor Maximum Dry Density (MPMDD). Due to the compressibility of the underlying soils we recommend that the building areas and roads be preloaded. We expect that 2 to 3 m of pit run sand and gravel preload, or other fill materials approved by GeoPacific, placed above the finished ground floor slab elevation will be required for buildings, and 1 m of preload above finished road level for roads. The actual preload height should be confirmed once foundation loads and final grading has been confirmed. The preload should extend at full height at least 1.5 m beyond the building or road area. We estimate that it will be necessary to leave the preload in place for 4 to 6 months to allow for primary consolidation settlements to be complete. However, ultimately, review of the preload performance will determine when the preload can be removed. The underlying soils are susceptible to liquefaction in the event of a large earthquake and therefore the site would be classified as “Site Class F” as per the BC Building Code. The buildings are expected to have a natural period of less than 0.5 second; therefore, the structural design can consider “Site Class E” for structural design purposes. We recommend that the homes be constructed on reinforced thickened slab foundations to help distribute loads and tie the structure together to prevent collapse should a large earthquake occur. Following the recommended site preparation and preload, the foundations can likley be designed for a maximum serviceability limit state (SLS) bearing pressure of 50 kPa and an ultimate limit state (ULS) of 100 kPa to be confirmed once structural loads are available. At least 100 mm of 19 mm clear crushed gravel should be placed below slabs and covered with a polyethylene moisture barrier to help reduce moisture levels within the grade supported slabs. After preloading and provided foundations are designed as described above, we estimate post-construction building settlements will be less than 60 mm with maximum differentials of 1 in 300. 6.3 Zone B – Upland Area on Glacial Till / Rock Site preparation for the proposed building lots would include removing all topsoil, roots, variable fill or debris encountered to expose the underlying natural subgrade of stiff silt or dense sand and gravel. If required, following stripping, clean well-graded pit run sand and gravel should be placed to the underside of foundations. The fill should be placed at this level to a distance of at least 1.5 m outside of each of the proposed building areas or distance equal to that of the fill, whichever is greater. The fill should be compacted in place to a minimum of 95% Modified Proctor Maximum Dry Density (MPMDD). The underlying soils are dense and are not considered susceptible to liquefaction in the event of a large earthquake. This zone of the site would be classified as “Site Class C” as per the BC Building Code. We expect that the buildings in this area homes can be constructed on conventional spread foundations.


Following the recommended site preparation, the foundations can be designed for a maximum serviceability limit state (SLS) bearing pressure of 200 kPa and an ultimate limit state (ULS) of 400 kPa. If foundations are supported directly on bedrock they can be designed for and SLS bearing pressure of 500 kPa and a ULS of 1 MPa. At least 100 mm of 19 mm clear crushed gravel should be placed below slabs and covered with a polyethylene moisture barrier to help reduce moisture levels within the grade supported slabs. For foundations designed as described above, we estimate post-construction building settlements will be less than 25 mm with maximum differentials of 1 in 300. 6.4 Zone C – Upland Area on Sand and Gravel / Rock Site preparation for the proposed building areas would include removing all topsoil, roots, variable fill or debris encountered to expose the underlying natural subgrade of dense glacial till or rock. If required, following stripping, clean well-graded pit run sand and gravel should be placed to the underside of foundations. The fill should be placed at this level to a distance of at least 1.5 m outside of each of the proposed building areas or distance equal to that of the fill, whichever is greater. The fill should be compacted in place to a minimum of 95% Modified Proctor Maximum Dry Density (MPMDD). We understand, based on discussions with contractors who worked on the site, that when the fairway for the golf course was constructed in this area the native sand and gravel was mined out down to bedrock and that poorer quality fill materials were placed to reinstate the ground to the current fairway elevation. Some wood debris was encountered within till-like fill materials along the fairway in this area. It is possible that poor quality fill will be encountered in this area which would need to be removed from beneath roads, sidewalks and buildings. Following the recommended site preparation the underlying soils would be dense and not considered susceptible to liquefaction in the event of a large earthquake. This zone of the site would be classified as “Site Class C” as per the BC Building Code. We expect that the buildings in this area homes can be constructed on conventional spread foundations. Following the recommended site preparation, the foundations can be designed for a maximum serviceability limit state (SLS) bearing pressure of 150 kPa and an ultimate limit state (ULS) of 300 kPa. If foundation are supported directly on bedrock they can be designed for and SLS bearing pressure of 500 kPa and a ULS of 1 MPa. At least 100 mm of 19 mm clear crushed gravel should be placed below slabs and covered with a polyethylene moisture barrier to help reduce moisture levels within the grade supported slabs. For foundations designed as described above, we estimate post-construction building settlements will be less than 25 mm with maximum differentials of 1 in 300. 6.5 Zone D – Southern Flood Plain The scope of our investigation did not include test holes within the southern flood plain. Previous work in this area in 2006 and discussion with contractors involved with the construction of the golf course, indicates that there could be significant peat beneath the eastern half of the southern flood plain. Any development considered for the western half of the southern flood plain should be as per our recommendations for Zone A.


We expect that townhomes and/or apartments could be considered for this area. Site preparation for townhomes or apartments would include removing all topsoil, surficial peat, roots, variable fill or debris encountered to expose the underlying natural subgrade of silt, sand. Following stripping, clean well-graded pit run sand and gravel should be placed to the top of the lower slab level of the building or FCL and at least 1.5 m of fill will be required for roads. The fill should extend, at this level, at least 3 m outside of the building area. The fill should be compacted in place to a minimum of 95% Modified Proctor Maximum Dry Density (MPMDD). It is recommended to place structures in this area on piles as foundations over peat could experience long term total and differentials settlements. Due to the compressibility of the underlying peat, we recommend that the building areas and roads be preloaded to help reduce differential settlement between the pile supported structures and surrounding grades. The building areas and roads should be preloaded with at least 1 m of pit run sand and gravel or other fill materials approved by GeoPacific finished site grades and allowed to settle. The preload should extend at full height at least 1.5 m beyond the building and road areas. We estimate that it will be necessary to leave the preload in place for 8 to 12 months to allow for primary consolidation settlements to be complete. However, ultimately, review of the preload performance will determine when the preload can be removed. The underlying soils are susceptible to liquefaction and/or strain softening in the event of a large earthquake and therefore the site would be classified as “Site Class F” as per the BC Building Code. The building are expected to have a natural period of less than 0.5 second; therefore, the structural design can consider “Site Class E” for structural design purposes. Once the preload is complete and material removed foundation piles could be installed. We expect that timber piles driven to the underlying dense sand or bedrock would be suitable to support the relatively light structures being considered. The underlying soils are susceptible to liquefaction and/or strain softening in the event of a large earthquake. Therefore, we recommend that the foundation pile caps be tied together to help distribute loads and tie the structure together and to prevent collapse should a large earthquake occur. At least 100 mm of 19 mm clear crushed gravel should be placed below slabs and covered with a polyethylene moisture barrier to help reduce moisture levels with the grade supported slabs. An underslab methane collection system would be required to capture and release any methane generated from the decomposition of the peat. All underslab services and utilities will need to be hung from the slab and flexible connections will be required where they transition to being grade supported outside of the building area. After preloading and provided foundations are designed as described above, we estimate post-construction building settlements will be less than 20 mm with maximum differentials of 1 in 300. However, settlement between the building and surrounding soils will continue and maintenance will likely be required to ensure that transitions are safe and acceptable. 6.6 Comments on Existing Northern Slopes The existing slopes along the northern property line are up to about 6 m high and comprised of cobbly sand and gravel. The top of the slope is near-to the north property line and slopes are at about 1.5H to 1V. We understand that these slopes are the remnants of the fill materials which were historically mined out of this


area and that the materials along the golf course side of the slope were removed. The proposed development plan includes townhomes near-to these slopes. If necessary the townhomes can be designed to abut into the slope and be backfilled as needed. The structural design for any foundation walls backfilled next to the slopes would need to consider seismic loading of the adjacent slopes on foundation walls. 7.0 CLOSURE This report should be considered preliminary until further design information and additional geotechnical information is available. It has been prepared solely for use by our client’s Design Team for this project as described to the general standards of similar work for similar projects in this area and no other warranty of any kind is expressed or implied. GeoPacific Consultants Ltd. accepts no responsibility for any other use of this report. We are pleased to assist you with this project and we trust this information is helpful and sufficient for your purposes at this time. Please contact the undersigned should require clarification or additional details. For: GeoPacific Consultants Ltd. Reviewed by: April 1, 2016 Adam Jessop, B.Eng., EIT Steven Fofonoff, M.Eng., P.Eng. Junior Engineer Senior Geotechnical Engineer

APPENDIX A - TEST HOLE LOGS

TH16-0113714

GARIBALDI SPRINGS GOLF COURSEPOLYGON DEVELOPMENT LTD

TANTALUS ROAD, SQUAMISH, BC

Ground SurfaceGrass and topsoilSand and gravel

dense SAND and GRAVEL, some fines, some rooty organics, brown, slightly moist

Sand and graveldense coarse grained SAND and GRAVEL, some cobbles, angular, brown, drygrey-brown after 0.9mbrown and slightly moist after 1.8m

no cobbles after 4.6mgrey after 4.9m

End of Borehole

0.0

0.3

6.1

9.1

8.5

10 20 30 40(blows per foot)

DCPT

water table not reached or determined

EDSolid stem auger

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Ground elevationA.01

Test Hole Log:File:Project:Client:Site Location:

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Page: 1 of 1Figure Number:

215 - 1200 West 73rd Avenue, Vancouver, BC, V6P 6G5Tel: 604-439-0922 Fax:604-439-9189

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TH16-0213714



Ground SurfaceGrass and topsoil

Siltstiff to very stiff sandy SILT, brown, moist

Sand and graveldense SAND and GRAVEL, angular, grey, dryslightly moist after 1.5m

wet after 3.4m

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3.4m estimated water table depth

auger refusal at 4.4m on bedrock

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TH16-0313714




Siltstiff to very stiff SILT, some sand and fine gravel, brown, slightly moist

Sand and graveldense SAND and GRAVEL, some fines, trace woody organics, brown, moistabundant wood fibre from 1.5m to 1.8mtrace to some wood fibre after 1.8m

moist to wet after 4.3m

Sand and graveldense angular SAND and GRAVEL, some cobbles, grey, moist to wet

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43.7

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TH16-0413714




grass over sandy TOPSOIL, brown, moist to wet

Sand and gravelcompact to dense silty SAND and GRAVEL, brown, slightly moist

Sand and graveldense SAND and GRAVEL, trace wood fibre, trace cobbles, brown, dry

wet after 3.4m

SandSAND, grey, wet

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4.64.7

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25.5


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auger refusal on bedrock at 4.7m

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TH16-0513714




grass over silty sand TOPSOIL, brown, moist

Sandcompact coarse grained SAND, some gravel,brown, slightly moist

Sand and gravelcompact to dense SAND and GRAVEL, trace to some cobbles, grey, dry

Sandcompact to dense medium grained SAND, grey, drywet after 2.6m

Sand gravel and cobblesdense SAND GRAVEL COBBLES and BOULDERS

End of Borehole

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no sample recovery after 3.0m

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TH16-06 (CPT16-01)13714




Sandcompact SAND fill, grey, wet

Siltvery stiff SILT, grey-brown, slightly moistabundant wood fibre from 0.3m to 0.9mstiff after 0.7mmoist after 0.9mfirm after 1.0msoft after 1.8msome organics from 1.8m to 2.1mtrace to some sand after 2.3msome organics at 2.7m

Silt and sandsoft to firm sandy SILT to silty SAND, brown, wet

grey after 4.0m

Sandloose to compact medium grained SAND, grey, wet

some fines after 6.1m

Sand and gravelcompact to dense subrounded SAND and GRAVEL, grey, wet

End of Borehole

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4.7

6.7

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50.8

56.4

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67.1

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DCPT

1.0m estimated water table depth based on disspation test at 7.10m

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TH16-07 (CPT16-02)13714




Sandcompact SAND fill, brown, wet

Siltvery stiff SILT, some fine sand, brown to grey, slightly moiststiff after 0.5msome wood fibre from 0.8m to 1.4m

Sandcompact to loose medium to fine grained SAND, trace fines, grey-brown, wet

Sandloose silty SAND, grey-brown, wet

SILT and SAND from 4.9m to 5.8m

Sand and gravelcompact to dense medium to coarse grained SAND and GRAVEL, grey, wet

End of Borehole

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1.8

3.0

7.0

7.6

50.7

49.4

36.3

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DCPT

1.0m estimated water table depth based on disspation test at 6.95m

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TH16-0813714





Silt sand and gravelcompact/stiff SILT SAND and GRAVEL fill, slightly moistcompact/soft and wet after 0.8m

Peatstiff PEAT, some wood fibre, brown, moist

Siltfirm SILT, grey-brown, moist

End of Borehole

0.0

1.5

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2.4

21.5

58.1

48.5


DCPT


auger refusal on bedrock at 2.4m

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1

1

2

2

3

3

4

4

5

5

6

6

7

7

8

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

Sym

bol

SOIL DESCRIPTION

Dep

th (m

)/Ele

v (m

)

Moi

stur

e C

onte

nt (%

)

Gro

undw

ater

/ W

ell

Remarks

TH16-0913714





Sand and gravelcompact SAND and GRAVEL, trace fines, brown, moist

Siltvery stiff to hard sandy SILT, light brown, slightly moistSILT after 1.7m

some sand and gravel after 3.0m

Silthard gravelly sandy SILT, light brown, slightlymoist

very stiff to stiff and moist after 4.6m

Sand and gravelvery dense cobbly SAND and GRAVEL, some fines, light brown, wet

End of Borehole

0.0

1.1

3.7

5.55.6

23.2

26.9


DCPT


auger refusal on cobbles and boulders at 5.6m

EDSolid stem auger

2016-3-8



Logged:Method:Date:

Datum:



INFERRED PROFILE

Dep

th

0 0ft m

1

1

2

2

3

3

4

4

5

5

6

6

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7

8

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SOIL DESCRIPTION

Dep

th (m

)/Ele

v (m

)

Moi

stur

e C

onte

nt (%

)

Gro

undw

ater

/ W

ell

Remarks

TH16-1013714





Sand and graveldense gravelly SAND, grey, slightly moistSAND and GRAVEL after 0.9m

wet after 2.1m

Sand and gravelvery dense silty SAND and GRAVEL, grey, moist

End of Borehole

0.0

4.6

5.8

10.0

6.6

8.3


DCPT


auger refusal on cobbles and boulders at 5.8m

EDSolid stem auger

2016-3-8



Logged:Method:Date:

Datum:



INFERRED PROFILE

Dep

th

0 0ft m

1

1

2

2

3

3

4

4

5

5

6

6

7

7

8

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Sym

bol

SOIL DESCRIPTION

Dep

th (m

)/Ele

v (m

)

Moi

stur

e C

onte

nt (%

)

Gro

undw

ater

/ W

ell

Remarks

TH16-1113714



Ground SurfaceTopsoil

sandy TOPSOILSand and gravel

dense to very dense SAND and GRAVEL, grey, drywet after 1.2m

End of Borehole

0.0

4.6

8.6


DCPT


EDSolid stem auger

2016-3-8



Logged:Method:Date:

Datum:



INFERRED PROFILE

Dep

th

0 0ft m

1

1

2

2

3

3

4

4

5

5

6

6

7

7

8

8

9

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11

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17

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19

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26

27

Sym

bol

SOIL DESCRIPTION

Dep

th (m

)/Ele

v (m

)

Moi

stur

e C

onte

nt (%

)

Gro

undw

ater

/ W

ell

Remarks

1 Robertson, P.K., 1990, "Soil Classification using the cone penetration test", 1990 Canadian Geotechnical Colloquium,Canadian Geotechnical Journal, Vol. 27, No. 1, 1990

APPENDIX B - ELECTRONIC CONE PENETRATION RESULTS

The system used is owned and operated by GeoPacific and employs a 35.7mm diameter cone that records tip resistance, sleeve friction, dynamic porepressure, inclination and temperature at 5 cm intervals on a digitalcomputer system. The system is a Hogentogler electronic cone system andthe cone used was a 10 ton cone with pore pressure element located behindthe tip and in front of the sleeve as shown on the adjacent figure.

In addition to the capabilities described above, the cone can be stopped atspecified depths and dissipation tests carried out. These dissipation testscan be used to determine the groundwater pressures at the specified depth.This is very useful for identifying artesian pressures within specific layersbelow the ground surface.

Interpretation of the cone penetration test results are carried out bycomputer using the interpretation chart presented below by Robertson1.Raw data collected by the field computer includes tip resistance, sleevefriction and pore pressure. The tip resistance is corrected for waterpressure and the friction ratio is calculated as the ratio of the sleeve frictionon the side of the cone to the corrected tip resistance expressed as apercent. These two parameters are used to determine the soil behaviourtype as shown in the chart below. The interpreted soil type may bedifferent from other classification systems such as the Unified SoilClassification that is based upon grain size and plasticity.

Figure: B.01

GeoPacific Project #: 137142016-Mar-8

Sounding: CPT16-01

POLYGON DEVELOPMENT LTD

TANTALUS ROAD, SQUAMISH

0

1

2

3

0 50 100 150 200

TIP RESISTANCEQt (bar)

0 1 2 3 4 5 6 7 8

FRICTION RATIO Rf (%)

-10 0 10 20 30 40 50

PORE PRESSURE U2 (m H2O)

0 1 2 3 4 5 6 7 8 9 10 11 12

SOIL BEHAVIOUR TYPE **

0 0.5 1 1.5 2

SLEEVE FRICTIONFs (bar)

4

5

6

7

8

9

10

DEP

TH (m

)

Refusal at 7.10m

= estimated water table depth

** Based on Robertson et. al 19861 Sensitive Fine Grained 4 Silty Clay to Clay 7 Silty Sand to Sandy Silt 10 Gravelly Sand to Sand2 Organic Material 5 Clayey Silt to Silty Clay 8 Sand to Silty Sand 11 Very Stiff Fine Grained3 Clay 6 Sandy Silt to Clayey Silt 9 Sand 12 Sand to Clayey Sand


Figure: B.02


Sounding: CPT16-02



0

1

2

3

0 50 100 150 200


0 1 2 3 4 5 6 7 8

FRICTION RATIO Rf (%)

-10 0 10 20 30 40 50

PORE PRESSURE U2 (m H2O)

0 1 2 3 4 5 6 7 8 9 10 11 12


0 0.5 1 1.5 2

SLEEVE FRICTIONFs (bar)

4

5

6

7

8

9

10

DEP

TH (m

)


Refusal at 6.95m

** Based on Robertson et. al 19861 Sensitive Fine Grained 4 Silty Clay to Clay 7 Silty Sand to Sandy Silt 10 Gravelly Sand to Sand2 Organic Material 5 Clayey Silt to Silty Clay 8 Sand to Silty Sand 11 Very Stiff Fine Grained3 Clay 6 Sandy Silt to Clayey Silt 9 Sand 12 Sand to Clayey Sand


2 Robertson, P.K., 1985, "In-Situ Testing and Its Application to Foundation Engineering", 1985 Canadian GeotechnicalColloquium, Canadian Geotechnical Journal, Vol. 23, No. 23, 1986

APPENDIX C - INTERPRETED PARAMETERS

The following charts plot the Standard Penetration Test (SPT) values and the undrained strength of fine grained soilsbased upon generally accepted correlations. The methods of correlation are presented below.

STANDARD PENETRATION TEST CORRELATION

The Standard Penetration Test N1(60) value is related to the cone tip resistance through a Qc/N ratio that depends uponthe mean grain size of the soil particles. The soil type is determined from the interpretation described in Appendix Band the data of Table C.1 below is used to calculate the value of N(60).

Table C.1. Tablulated Qc/N1(60) Ratios for Interpreted Soil Types

Soil Type Qc/N Ratio

Organic soil - Peat 1.0

Sensitive Fine Grained 2.0

Clay 1.0

Silty Clay to Clay 1.5

Clayey Silt to Silty Clay 2.0

Silt 2.5

Silty Sand to Sandy Silt 3.0

Clean Sand to Silty Sand 4.0

Clean Sand 5.0

Gravelly Sand to Sand 6.0

Very Stiff Fine Grained 1.0

Sand to Clayey Sand 2.0

The Qc/N1(60) ratio is based upon the published work of Robertson (1985)2. The values of N are corrected for overburdenpressure in accordance with the correction suggested by Liao and Whitman using a factor of 0.5. Where the correctionis of the form:

N1 = F0.5 * N

All calculations are carried out by computer using the software program CPTint.exe developed by UBC CivilEngineering Department. The results of the interpretation are presented on the following Figures.

UNDRAINED SHEAR STRENGTH CORRELATION

It is generally accepted that there is a correlation between undrained shear strength of clay and the tip resistance asdetermined from the cone penetration testing. Generally the correlation is of the form:

where qc = cone tip resistance, F = in situ total stress, Nk = cone constant

The undrained shear strength of the clay has been calculated using the cone tip resistance and an Nk factor of 12.5. Allcalculations have been carried out automatically using the program CPTint.exe. The results are presented on the Figuresfollowing.

APPENDIX C - OVER CONSOLIDATION RATIO ANALYSIS

The over consolidation ratio (OCR) is defined as the ratio between the maximum past vertical pressure onthe soil versus the current in-situ vertical pressure. The maximum past vertical pressure is typically causedby the presence of excess overburden which is removed by either natural or man-made reasons. Soil ageingand other chemical precipitation affects can also cause a soil to behave as if it has a higher maximum pastpressure, which is sometimes described as pseudo-overconsolidation.

Research by Schmertmann (1974) showed the following equation reasonably approximates the OCR ofmedium plastic to clayey soils:

OCR

Su p ocSu p nc

=

⎛⎝⎜

⎞⎠⎟ +

⎛

⎝

⎜⎜⎜⎜⎜

⎞

⎠

⎟⎟⎟⎟⎟

/ '/ '

.

.

/5 3

082

182

Su/p’oc = The undrained shear strength to effective stress ratio of the over consolidated soil

Su/p’nc = The undrained shear strength to effective stress ratio of a normally consolidated soil(OCR = 1). Typically = ~0.2

Soils which are subject to loads less than the maximum past pressure of the soil are typically subject torelatively small elastic settlements. Loads which exceed the maximum past pressure on the soil typicallycause consolidation which is the gradual settlement of the ground as a result of expulsion of water from thepores of the soil. The rate of settlement and the time to complete consolidation is a function of thepermeability of the soil.

The Schmertman equation has been employed to estimate the OCR of the soils with depth employing the CPTdata provided in Appendix B and C.

Figure: C.01


Sounding: CPT16-01



0

1

2

3

0 50 100 150 200


0 25 50 75 100 125 150 175 200

UNDRAINED SHEAR STRENGTHSu (kPa)

0 10 20 30 40 50

STANDARD PENETRATION TEST (SPT) N1(60)

0 1 2 3 4 5 6 7 8 9 101112


0 1 2 3 4 5 6 7 8 9 10

OVER CONSOLIDATION RATIO (OCR)

4

5

6

7

8

9

10

DEP

TH (m

)

Nkt=12.5** Based on Robertson et. al 1986

1 Sensitive Fine Grained 4 Silty Clay to Clay 7 Silty Sand to Sandy Silt 10 Gravelly Sand to Sand2 Organic Material 5 Clayey Silt to Silty Clay 8 Sand to Silty Sand 11 Very Stiff Fine Grained3 Clay 6 Sandy Silt to Clayey Silt 9 Sand 12 Sand to Clayey Sand

Nkt=12.5

Figure: C.02


Sounding: CPT16-02



0

1

2

3

0 50 100 150 200


0 25 50 75 100 125 150 175 200

UNDRAINED SHEAR STRENGTHSu (kPa)

0 10 20 30 40 50

STANDARD PENETRATION TEST (SPT) N1(60)

0 1 2 3 4 5 6 7 8 9 101112


0 1 2 3 4 5 6 7 8 9 10

OVER CONSOLIDATION RATIO (OCR)

4

5

6

7

8

9

10

DEP

TH (m

)

Nkt=12.5** Based on Robertson et. al 1986

1 Sensitive Fine Grained 4 Silty Clay to Clay 7 Silty Sand to Sandy Silt 10 Gravelly Sand to Sand2 Organic Material 5 Clayey Silt to Silty Clay 8 Sand to Silty Sand 11 Very Stiff Fine Grained3 Clay 6 Sandy Silt to Clayey Silt 9 Sand 12 Sand to Clayey Sand

Nkt=12.5

APPENDIX D - LIQUEFACTION ANALYSIS

Assessment of the liquefaction potential of the ground has been determined by the Cone Penetration Test (CPT).

The method of analysis is presented in the following sections.

FACTOR OF SAFETY AGAINST LIQUEFACTION The factor of safety against liquefaction calculated here is the ratio of the cyclic resistance of the soil (CRR) to the

cyclic stresses induced by the design earthquake (CSR). Where the ratio of CRR/CSR is greater than unity the soils

ability to resist cyclic stresses is greater than the cyclic stresses induced by the earthquake and liquefaction will be

unlikely. Where the CRR/CSR is less than unity then liquefaction could occur. This ratio is presented as the FOS

against Liquefaction on the following charts. Calculation of the factor of safety is based on NCEER (1998)1 which

evaluates the CRR directly from cone penetration test sounding data. The value of the cyclic stress ratio has been

calculated based on peak horizontal ground acceleration of 0.35g during the 2012 British Columbia Building Code

design earthquake, which is consistent with our experience in this area.

SEISMIC INDUCED SETTLEMENT In the event of a significant earthquake, settlement of the ground surface could occur as a result of densification of

the looser soil layers as a result of liquefaction or due to the expulsion of sand in the form of sand dykes or sills from

beneath the site. Tokimatsu and Seed (1987)2 suggest a method of analysis for estimating vertical settlements as a

result of earthquake induced accelerations. In this method the normalized standard penetration blow counts (N1(60))

is compared with the cyclic stress ratio for the induced earthquake to determine the volumetric strain resulting from

the earthquake shaking. The volumetric strain is assumed to result in only vertical settlement. The vertical

settlement is summed for each depth at which settlement is predicted to occur and accumulated from the bottom of

the test hole. The results are presented on the following charts labelled as Settlement.

HORIZONTAL DISPLACEMENT Horizontal ground displacements known as "free field" displacements occur as a result of liquefaction of the ground

and are assumed to occur without the influence of any structures. The horizontal displacements presented in our

report are generally based upon the lateral spread method by of Youd, Bartlett, & Hansen (2002). Displacements are

calculated based on an empirical relationship developed from observations from other earthquake sites on sloping

ground or near a free face, such as an abrupt slope. The presence of the proposed embankment on-site is expected to

induce a static bias within the soils at the margin of the embankment making the soils and embankment in this area

subject to lateral spread induced movements. In the event of a real earthquake of significant magnitude to cause

limited liquefaction, actual movements will be influenced by a wide variety of factors including the characteristics

of the earthquake including duration, number of significant cycles, variations in peak particle velocity, wavelength,

amplitude and frequencies as well as soil damping and variations in density and continuity of the soil layers.

1 Youd, T. L., Idriss, I. M. (2001). “Liquefaction Resistance of Soils: Summary Report from the 1996 and 1998

NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils”, Journal of Geotechnical and

Geoenvironmental Engineering, Vol 127, 10, pp. 817-833

2 Tokimatsu, K.A.M. and Seed, H.B., 1987. "Evaluation of Settlement in Sands Due to Earthquake Shaking", Journal of

Geotechnical Engineering, ASCE, Vol. 113, No. 8, pp. 861-878.

3 Youd, T.L., Bartlett, S.F., Hansen, C.M. (2002), "Revised MultiLinear Regression Equations for Prediction of Lateral Spread Displacements", Journal of Geotechnical and GeoEnvironmental Engineering, Vol. 128, No. 12, pp. 1007-1017

2016-Mar-8 POLYGON DEVELOPMENT LTD GeoPacific Project #: 13714

Sounding: CPT16-01 TANTALUS ROAD, SQUAMISH Figure: D.01

0

1

2

3

0 50 100 150 200


0 0.1 0.2 0.3 0.4 0.5

Cyclic Stress (CSR) and Cyclic Resistance (CRR)

Ratios 0.0 0.5 1.0 1.5 2.0

Factor of Safety (FL)

0 20 40 60 80 100

Fines Content FC (%)

0 100 200 300 400 500Settlement (mm)

4

5

6

7

8

9

10

DEP

TH (m

)

CSR CRR

Liquefaction interpretation ran with PGA = 0.33g

CSR CRR

2016-Mar-8 POLYGON DEVELOPMENT LTD GeoPacific Project #: 13714

Sounding: CPT16-02 TANTALUS ROAD, SQUAMISH Figure: D.02

0

1

2

3

0 50 100 150 200


0 0.1 0.2 0.3 0.4 0.5

Cyclic Stress (CSR) and Cyclic Resistance (CRR)

Ratios 0.0 0.5 1.0 1.5 2.0

Factor of Safety (FL)

0 20 40 60 80 100

Fines Content FC (%)

0 100 200 300 400 500Settlement (mm)

4

5

6

7

8

9

10

DEP

TH (m

)

CSR CRR

Liquefaction interpretation ran with PGA = 0.33g

CSR CRR

Documents

File: 13714 Proposed Comprehensive Development ......File: 13714 Proposed Comprehensive Development – Garibaldi Springs Golf Course, Squamish, BC Page 1 215 - 1200 West 73 Avenue