Geotechnical Investigation

Transcription

1 Geotechnical Investigation 11 July Gore Bay Road Gore Bay Submitted to: Alistair Dickson c/- Reuben Frizzell Survus Consultants Ltd PO Box 5558 Christchurch 8542 Geoscience Consulting (NZ) Limited 124 Montreal Street, Christchurch 8023, New Zealand PO Box 373, Christchurch 8140, New Zealand T (+64) (3) F (+64) (3)

2 Geotechnical Investigation 698 Gore Bay Road 2 Content 1 Introduction and Scope of Work Background Site Description Regional Geology Active Faulting Historic Photographs Field Investigations and Site Conditions Geotechnical Assessment Scala Penetrometer Testing Test Pit Excavations Geotechnical Assessment Building Platforms Site Access Geological Hazards Conclusions and Recommendations Assessment Against Section 106 of the Resource Management Act Slope Retention Building Platforms References Limitations... 14

3 Geotechnical Investigation 698 Gore Bay Road 3 Tables Table 1: Table 2: Nearby Active Faults Summary of Subsurface Conditions Figures Figure 1: Figure 2: Figure 3: Geological Setting Historic Aerial Photographs Site Photographs Appendices (at the rear of this report) Appendix 1: Appendix 2: Appendix 3: Appendix 4: Site Location Plan Geotechnical Mapping and Cross Sections Scala Penetrometer Test Results Test Pit Logs and Associated Scala Penetrometer Test Results Geoscience Document Control: Report Title Geotechnical Report 698 Gore Bay Road, Gore Bay Project No /001 Document ID 01 Client Alistair Dickson Client Contact Reuben Frizzell Distribution 1 Copy (PDF) Reuben Frizzell, Survus Consultants Distribution 1 Copy Geoscience Consulting (NZ) Ltd Rev Date Revision Details/Status WP Author Reviewer 1 11/7/14 Final BK LF RJ

4 Geotechnical Investigation 698 Gore Bay Road 4 1 Introduction and Scope of Work Geoscience Consulting (NZ) Ltd was requested by Hamish Frizzel, on behalf of Alistair Dickson, to undertake a geotechnical investigation of the property at 698 Gore Bay Road (herein referred to as the site ). We understand that you wish to subdivide the site into four lots and require a geotechnical assessment into the suitability of the ground conditions for subdivision. The scope of this study consisted of: A desktop study of geotechnical and geological publications; A geotechnical inspection of the site; Engineering geological mapping across the site, specifically focusing on landslide features; Arranging for the excavation of 4 machine excavated test pits to determine the subsurface types and characteristics; Completion of 7 Scala Penetrometer tests to confirm the soil strength; and Presentation of this report outlining our findings of the ground conditions and suitability for residential subdivision. This includes general geotechnical advice on foundation conditions, suitability of the proposed access and address Section 106 of the RMA. Our scope of works did not include provision of soil parameters for foundation or retaining structure design. 2 Background 2.1 Site Description The site is located on a ridge immediately above (west) the Gore Bay settlement in North Canterbury. The site is bound to the north and northwest by Buxton Creek, to the east by residential properties and to the south by currently undeveloped farm land. The site is currently undeveloped and used as grazing for livestock. The site is approximately 1.85 ha and is proposed to be subdivided into four lots as indicated in Appendix 1 (referenced as Building Platforms 1 to 4). Building Platform 1 is located to the northern end of the site and is located on a near horizontal platform, which appears to be a remnant river terrace. Building Platforms 2, 3 and 4 are located to the southern end of the site on a gently to moderately sloping area just below the main ridgeline. The northern and southern building platforms are linked by an access track which generally follows the ridgeline.

5 Geotechnical Investigation 698 Gore Bay Road Regional Geology The site is mapped by Rattenbury et al as being on the boundary between two geological units. The northern portion of the site is indicated to be underlain by undifferentiated sandstone and siltstone including the Waikari and Mount Brown Foundations (unit Mn), while the southern portion of the site is underlain by the Greta Formation, comprising marine siltstone, poorly bedded marine deltaic and fluvial mudstone, limestone, sandstone and conglomerate (unit Png). An exerpt from the Rattenbury et al map is presented in Figure 1. Overlying the rock units is a series of alluvial deposits, shown as Q series on Figure 1, below. The Alluvium typically comprises river gravel and sand with minor silt and fan deposits (units Q2a and Q8a) and postglacial deposits, including river gravel and sand in either fan or swamp deposits (units Q1a). Mantling the majority of the site is a layer of wind-blown Silt (Loess), with topsoil being developed on most of the gently to moderately sloping surfaces. Figure 1: Geological Setting Site Area Excerpt from Rattenbury et al. 2006

6 Geotechnical Investigation 698 Gore Bay Road Active Faulting GNS Science has complied a database of active faults throughout New Zealand. A review of this database indicates that the site is located within an area of relatively active seismicity. The faults presented in Table 1 are mapped within the site area. Table 1: Nearby Active Faults Distance From Site (approximate) Fault Name Recurrence Interval 9 km south Unnamed No data available 15 km west Kaiwara Fault years 20 km west Mt Alexander Fault No data available 2.4 Historic Photographs We have reviewed historic aerial photographs of the site area dated 1955, 1985 and These are presented in Figure 2 below.

7 Geotechnical Investigation 698 Gore Bay Road 7 Figure 2: Historic Aerial Photographs Aerial photographs from 1955 and 985 sourced from NZ Aerial Mapping Ltd, 2013 photograph from Canterbury Maps.

8 Geotechnical Investigation 698 Gore Bay Road 8 A summary of the key features identified is presented below: Minimal change was observed in the surface morphology from 1955 to present day. The apparent change in cliff line position appears to be mostly an effect of vegetation removal and not ground loss; Significant vegetation growth has occurred along the step banks of Buxton Creek from 1955 to the present day. This suggests that these are not experiencing rapid erosion; and The access track was present by the time of the 1985 photograph. This may have caused changes to the lower slopes in this area. 3 Field Investigations and Site Conditions 3.1 Geotechnical Assessment Geoscience visited the site on 24 June 2014 and made the following observations: The western and northern boundaries of the site are located along steeply sloping banks, dropping down to Buxton Creek; The eastern boundary of the site is a vegetated slope which descends to the residential properties on the boundary; The site is underlain by interbedded sandstone/siltstone. In exposure along Buxton Stream, siltstone units within the sequence reach up to 2 m in thickness and are typically very weak. The sandstone ranges in strength from very weak to moderately strong. Joints within the sedimentary sequence appear to be typically widely spaced and appear to have developed parallel to the steep slope faces. It is interpreted that these represent stress relief jointing within the rock mass; Bedding within the sandstone/siltstone unit was observed to be moderately inclined and dipping to the east to south-east. This is a favorable orientation for rock mass stability for the subject site; In exposure, the sandstone/siltstone sequence is unweathered to slightly weathered and typically grey in colour. However, the upper few metres of the sequence is distinctly more weathered and is likely to have a lower strength; Overlying the sandstone/siltstone sequence is a low angle sand/gravel unit, which is interpreted to be an elevated alluvial terrace. Terrace remnants can be recognized in the northwestern corner of the proposed subdivision and in the around proposed Building Platform 1; An access track has been cut and extends from the flat to the top of the site along the ridgeline. The lower portion of the access track is steeply sloping, however we understand through discussion with the land owner, that this has been checked as an appropriate gradient (pers. comm. Alistair Dickson); Access between the lower (1) and upper (2, 3 and 4) building platforms crosses a narrow portion of the ridge, where previous collapse has occurred along the western side;

9 Geotechnical Investigation 698 Gore Bay Road 9 Ground cracks and signs of soil creep were observed in the slope immediately downslope of the lower portion of the access track (near Building Platform 1); The upper building platforms (2, 3 and 4) are across a broad gully to the west of the main ridgeline. The gully acts to channel water off the hill slope into this area, resulting in the formation of a series of erosion gullies observed in the steeply sloping bank on the northwestern site boundary; Formation of tunnel gully erosion channels in the surficial soils was observed on the cut slopes of the access way. Further tunnel gully erosion may exist across the site, however any evidence of this was obscured by vegetation at the time of our site visit; Immediately downslope of the lowest building platform is a small pond. The orientation of bedding was not observed to change in observed exposures either side of the pond. The pond is therefore interpreted to represent an elevated abandoned channel of the Buxton Stream, and is not thought to be as a result of mass movement. We consider that the pond is the remnant of an abandoned stream channel. This likely to have formed as Buxton Stream cut through the elevated river terraces, before the water course took a new channel and continued to incise; Significant seepage was observed from the slope below the upslope building platforms; Steeply sloping banks were observed downslope of all building platforms. Based on our observations of historical aerial photographs, these do not appear to be receding rapidly, however we consider that appropriate setbacks will be required to ensure the safety of the proposed building platforms; and To the west of the site is a lower area which is sub-horizontal. Based on this geomorphology we consider this to be an old river terrace. It appears to correlate with the terrace for the lower proposed building platform. Geotechnical mapping, with associated cross sections detailing the features described above, are presented in Appendix 2. Site photographs are presented in Figure 3 below.

10 Geotechnical Investigation 698 Gore Bay Road 10 Figure 3: Site Photographs Photo 1: View of site from neighbouring site to the north Photo 2: Location of upslope building platforms (highlighted) Photo 3: Steep banks downslope of building platforms Photo 4: Ground cracks and soil creep downslope of access road 3.2 Scala Penetrometer Testing Two Scala Penetrometer tests (SP) were completed adjacent to each building platform (Appendix 3). Tests SP1 to SP4 were completed from ground level, while additional Scala tests were completed within the machine excavated test pits (see logs of TP1 to TP4) typically 0.5 m below ground level. Scala results are presented in Appendix 3 and 4. The Scala tests were undertaken to assess the subsurface strength profile and to determine if ground beneath the site meets the requirements of good ground, defined in NZS 3604:2011 as follows: Where the number of blows per 100 mm depth of penetration below the underside of the proposed footing at each test site exceeds: 5 down to a depth equal to twice the width of the widest footing; and 3 at greater depths.

11 Geotechnical Investigation 698 Gore Bay Road 11 Furthermore, the definition of good ground also excludes organic topsoil, peat, soft or very soft clay and / or uncertified fill below the depth of footing at any test site. Good ground was consistently encountered below 0.9 m depth in the test locations; however, further site specific testing will be required to determine bearing capacities and depth to good ground at the location of each building platform. 3.3 Test Pit Excavations Geoscience supervised the excavation of four test pits by Worthington Contracting on 24 June These were completed adjacent to each building platform. Test pit locations (TP01-04) are presented in Appendix 1. Our investigations found the geology to be consistent with published mapping, as summarised in Table 2. Table 2: Summary of Subsurface Conditions Depth (m) Soil Type Density/Consistency Upslope building platforms 0.0 to 0.4 Silt [TOPSOIL] Firm 0.4 to 2.0 Sandy SILT [ALLUVIUM] 1 Firm to Hard 1.4 to 1.8 Sandy SILT [SILTSTONE] Hard Soil, becoming Very Weak Rock Downslope building platform 0.0 to 0.5 Sandy SILT [TOPSOIL] Firm 0.5 to 0.6 Sandy SILT [ALLUVIUM] Stiff 0.6 to 2.1 SAND and GRAVEL [ALLUVIUM] Medium Dense to Dense >2.1m SILTSTONE Hard Soil, becoming Very Weak Rock 1 Sand was encountered within test pit TP03 from 1.3 m to 2.0 m depth. Standing water was not encountered within the upslope test pit investigations (TP2 to TP4), however in the downslope test pit (TP01) it was encountered within the gravel material from 1.6 m depth. Full logs are presented in Appendix 4 and are written in accordance with the New Zealand Geotechnical Society Guideline for the Field Classification and Description of Soil and Rock for Engineering Purposes.

12 Geotechnical Investigation 698 Gore Bay Road 12 4 Geotechnical Assessment 4.1 Building Platforms Owing to the steeply sloping banks along the north-western boundary of the site, we recommend the following setbacks: A minimum of 10 m from each bank for Building Lot 1; and A minimum of 20 m from the head of erosion gullies for Building Lots 2 to 4 with cut-off drainage to be installed as outlined below. As significant seepage was observed from the slope below building platforms, we recommend that drainage is incorporated into the site development plan downslope of Building Lots 2, 3 and 4. We recommend that a cut-off drain is installed at the top of the banks along the 5 m set back line. The drainage system would be comprised of a perforated field drain placed in the base of a 1 m (minimum) deep trench. The trench should be backfilled with coarse free draining and lined with a non-woven geotextile. The trench should then be discharged to a suitable point well either well away from the crest of the steep slope above Buxton Creek, or directed down the face to discharge on the alluvial slopes below. A collapsible flume would be suitable in this regard. 4.2 Site Access If the site access is to be kept in the current configuration, some slopes may require retaining solutions to support the roadway. These areas have been identified in the site location plan (Appendix 1). Suitable retaining structures may include either cantilevered or tied-back timber pole walls. We do not consider the pond, located upslope of the proposed access way, to pose a significant risk to the permanent access to the proposed building platforms. Based on the geomorphology of the site, this pond appears to be associated with an old stream channel rather than being associated with large scale land movement. 4.3 Geological Hazards We do not consider that the proposed building platforms are located in areas prone to land sliding, as they are typically located on or near a ridgeline. Provided the set-backs detailed above are complied with for development, we do not consider that future development will increase the likelihood of land sliding. Any slope regression should not affect the building platforms provided the set-backs are complied with. We do not consider the proposed building platforms to be at risk to flooding hazards owing to their locations on, or near, a ridge line. We have not assessed the risk of tsunami at the site, however this is assumed to be relatively low given the elevations of the proposed development areas.

13 Geotechnical Investigation 698 Gore Bay Road 13 5 Conclusions and Recommendations 5.1 Assessment Against Section 106 of the Resource Management Act We consider the proposed building platforms (if utilising the setbacks detailed above), not to be presently subject to erosion, falling debris, slippage, subsidence or inundation by soil or rock in accordance with the provision of Section 106 of the Resource Management Act We do not consider that future residential use of the land is likely to accelerate, worsen or result in material damage to the land provided that proper engineering practices are followed during any development, including those recommended in this report. If the guidance presented above, in terms of setbacks, drainage and retaining structures is complied with, we then consider that the site is suitable for subdivision and further development. 5.2 Slope Retention If the site access is to remain in its current configuration, retaining structures will be required to support isolated areas of the roadway. Specific geotechnical design and investigation will be required to ensure that these structures are built to an appropriate standard. 5.3 Building Platforms For foundation design, based on our initial testing, we consider that good ground can be encountered below 0.9 m depth. We note that this is indicative only and may vary from building platform to building platform. Site specific testing should be undertaken at the building consent stage to confirm this depth. Any existing erosion channels or tunnel gullies, within 5 m upslope of the proposed building platforms, should be filled with low permeability materials so as to prevent further channelling of water through these features. 6 References GNS Science (2014). New Zealand Active Faults Database, accessed June 2014 from New Zealand Geotechnical Society (2005). Guideline for the Field Classification and Description of Soil and Rock for Engineering Purposes. Rattenbury, M.S., Townsend, D.B., Johnston, M.R., (2006). Geology of the Kaikoura area. Institute of Geological & Nuclear Sciences 1: geological map sheet + 70 p. Lower Hutt, New Zealand: GNS Science. Standards Association of New Zealand (2011). Timber Framed Buildings New Zealand, NZS 3604:2011. Standards New Zealand, Wellington.

14 Geotechnical Investigation 698 Gore Bay Road 14 7 Limitations i. We have prepared this report in accordance with the brief as provided. This report has been prepared for the use of our client, Alistair Dickson, his professional advisers and the relevant Territorial Authorities in relation to the specified project brief described in this report. No liability is accepted for the use of any part of the report for any other purpose or by any other person or entity. ii. iii. iv. The recommendations in this report are based on the ground conditions indicated from published sources, site inspections and subsurface investigations described in this report based on accepted normal methods of site investigations. Only a limited amount of information has been collected to meet the specific financial and technical requirements of the Client s brief and this report does not purport to completely describe all the site characteristics and properties. The nature and continuity of the ground between test locations has been inferred using experience and judgement and it must be appreciated that actual conditions could vary from the assumed model. Subsurface conditions relevant to construction works should be assessed by contractors who can make their own interpretation of the factual data provided. They should perform any additional tests as necessary for their own purposes. This Limitation should be read in conjunction with the IPENZ/ACENZ Standard Terms of Engagement. v. This report is not to be reproduced either wholly or in part without our prior written permission. We trust that this information meets your current requirements. Please do not hesitate to contact the undersigned on if you require any further information. Report prepared by Reviewed by Lauren Foote Staff Geologist Richard Justice, PEngGeol Principal Geologist

15 Appendix 1 Site Location Plan

16 Buxton Creek 1 TP01 SP01 Area of ground cracks beneath access track TP04 SP04 4 TP03 SP TP02 SP02 = Test Location Note: Images sourced from Google Maps and Edge Landscapes 1 Current access track Proposed lot Areas requiring retention Date Jul-14 Client Alistair Dickson Drawn by LF Project Geotechnical Investigation Approved by RJ Description Site Location Plan Scale NTS Geoscience Ref

17 Appendix 2 Geotechnical Mapping and Cross Sections

18 LEGEND Crest of steep slope Active slope instability Ridge crest Gully axis Inactive slope instability Talus/alluvial fan Area of bedrock outcrop Measured strike and dip of bedding Cross section location

19 Date Jul-14 Client Alistair Dickson Drawn by RJ Project Geotechnical Investigation Approved by LF Description Geotechnical Cross Section 1-1 Scale (approx.) 1:500 Geoscience Ref

20 Date Jul-14 Client Alistair Dickson Drawn by RJ Project Geotechnical Investigation Approved by LF Description Geotechnical Cross Section 2-2 Scale (approx.) 1:500 Geoscience Ref

21 Date Jul-14 Client Alistair Dickson Drawn by RJ Project Geotechnical Investigation Approved by LF Description Geotechnical Cross Section 3-3 Scale (approx.) 1:500 Geoscience Ref

22 Appendix 3 Scala Penetrometer Test Results

23 LOG OF SCALA SP Gore Bay Road Gore Bay Project Number Client Client Ref. Date : : Alistair Dickson : N/A : 24/06/14 Logged By : LF/RJ Reviewed By : JM Latitude : Longitude : Depth (m) SCALA PENETROMETER BLOWS PER 100 MM BLOWS NOTES/ REMARKS GEOSCIENCE SCALA BLANK TEMPLATE.GPJ NZ DATA TEMPLATE 2.GDT 7/7/14 Scala Penetrometer met practical refusal on hard material at 1.3 m depth.

24 LOG OF SCALA SP Gore Bay Road Gore Bay Project Number Client Client Ref. Date : : Alistair Dickson : N/A : 24/06/14 Logged By : LF/RJ Reviewed By : JM Latitude : Longitude : Depth (m) SCALA PENETROMETER BLOWS PER 100 MM BLOWS NOTES/ REMARKS GEOSCIENCE SCALA BLANK TEMPLATE.GPJ NZ DATA TEMPLATE 2.GDT 7/7/14 Scala Penetrometer met practical refusal on hard material at 1.3 m depth.

25 LOG OF SCALA SP Gore Bay Road Gore Bay Project Number Client Client Ref. Date : : Alistair Dickson : N/A : 24/06/14 Logged By : LF/RJ Reviewed By : JM Latitude : Longitude : Depth (m) SCALA PENETROMETER BLOWS PER 100 MM BLOWS NOTES/ REMARKS GEOSCIENCE SCALA BLANK TEMPLATE.GPJ NZ DATA TEMPLATE 2.GDT 7/7/14 Scala Penetrometer met practical refusal on hard material at 1.6 m depth. 11

26 LOG OF SCALA SP Gore Bay Road Gore Bay Project Number Client Client Ref. Date : : Alistair Dickson : N/A : 24/06/14 Logged By : LF/RJ Reviewed By : JM Latitude : Longitude : Depth (m) SCALA PENETROMETER BLOWS PER 100 MM BLOWS NOTES/ REMARKS GEOSCIENCE SCALA BLANK TEMPLATE.GPJ NZ DATA TEMPLATE 2.GDT 7/7/14 Scala Penetrometer met practical refusal on hard material at 0.9 m depth.

27 Appendix 4 Test Pit Logs and Associated Scala Penetrometer Test Results

28 1 2 3 LOG OF TEST PIT TP Gore Bay Road Gore Bay Client Date Max Test Pit Depth Digger Type/Size Bucket Type/Size : Alistair Dickson : 24/06/14 : 2.1 m : Bucket Excavator : Flat edge bucket, 2 m wide Shear Vane No Logged By Reviewed By Latitude Longitude : : LF : JM : : Depth (m) Material TOPSOIL Excavatability (Relative Scale) Easier Harder USCS Symbol SM DESCRIPTION Sandy SILT; dark brown. Low plasticity. Sand, fine, poorly graded, subrounded to subangular [TOPSOIL]. Graphic Symbol Water Level Moisture Cond. M F SM Sandy SILT; light yellowish brown. Low plasticity. Sand, fine, poorly graded, subrounded to subangular. Fine to medium SAND; light brown with orange mottles. Poorly graded, subrounded to subangular. St SP W MD-D ALLUVIUM Consistency/ Density Index Shear Vane Undrained Shear Strength Peak/Remolded (kpa) Scala Penetrometer Blows per 100mm GEOSCIENCE TEST PIT LOG BLANK TEMPLATE.GPJ NZ MASTER DATA TEMPLATE.GDT 7/7/ SW Gravelly fine to coarse SAND with minor cobbles; light brown. Well graded, sub-rounded to sub-angular. Gravel, fine to coarse, well graded, subrounded to rounded. Cobbles, subrounded to rounded. Depth of Excavation: 2.1 m Termination Condition: Practical refusal Test pit met practical refusal on hard material at 2.1 m depth. Scala Penetrometer met practical refusal at 1.1 m depth. Standing water was encountered from 1.6 m depth. S D

29 1 2 3 LOG OF TEST PIT TP Gore Bay Road Gore Bay Client Date Max Test Pit Depth Digger Type/Size Bucket Type/Size : Alistair Dickson : 24/06/14 : 1.6 m : Bucket Excavator : Flat edge bucket, 2 m wide Shear Vane No Logged By Reviewed By Latitude Longitude : : LF : JM : : Depth (m) Material TOPSOIL Excavatability (Relative Scale) Easier Harder USCS Symbol ML DESCRIPTION SILT; dark brown. Low plasticity [TOSPOIL]. Graphic Symbol Water Level Moisture Cond. Consistency/ Density Index F Shear Vane Undrained Shear Strength Peak/Remolded (kpa) Scala Penetrometer Blows per 100mm Sandy SILT; light yellowish brown with organge mottles. M St-VSt 1.0 ALLUVIUM SM No orange mottles from 1.0 m depth. Becomes dry. D H >> 1.5 Depth of Excavation: 1.6 m Termination Condition: Practical refusal GEOSCIENCE TEST PIT LOG BLANK TEMPLATE.GPJ NZ MASTER DATA TEMPLATE.GDT 7/7/ Test pit met practical refusal on hard material at 1.6 m depth. Scala Penetrometer met practical refusal at 1.4 m depth. Standing water was not encountered.

30 1 2 3 LOG OF TEST PIT TP Gore Bay Road Gore Bay Client Date Max Test Pit Depth Digger Type/Size Bucket Type/Size : Alistair Dickson : 24/06/14 : 2 m : Bucket Excavator : Flat edge bucket, 2 m wide Shear Vane No Logged By Reviewed By Latitude Longitude : : LF : JM : : Depth (m) Material TOPSOIL Excavatability (Relative Scale) Easier Harder USCS Symbol ML DESCRIPTION SILT; dark brown. Low plasticity [TOPSOIL]. Graphic Symbol Water Level Moisture Cond. Consistency/ Density Index F Shear Vane Undrained Shear Strength Peak/Remolded (kpa) Scala Penetrometer Blows per 100mm Sandy SILT; yellowish brown with orange mottles. Low plasticity. Sand, fine, poorly graded. M SM St-H ALLUVIUM Fine SAND with some silt; light grey with orange mottles. Poorly graded, subrounded to subangular. Silt, low plasticity. SP W D GEOSCIENCE TEST PIT LOG BLANK TEMPLATE.GPJ NZ MASTER DATA TEMPLATE.GDT 7/7/ Depth of Excavation: 2 m Termination Condition: Practical refusal Test pit met practical refusal on hard material at 2.0 m depth. No Scala Penetrometer data recorded. Standing water was not encountered.

31 1 2 3 LOG OF TEST PIT TP Gore Bay Road Gore Bay Client Date Max Test Pit Depth Digger Type/Size Bucket Type/Size : Alistair Dickson : 24/06/14 : 1.8 m : Bucket Excavator : Flat edge bucket, 2 m wide Shear Vane No Logged By Reviewed By Latitude Longitude : : LF : JM : : Depth (m) Material TOPSOIL Excavatability (Relative Scale) Easier Harder USCS Symbol ML DESCRIPTION SILT with some sand; dark brown. Sand, fine, poorly graded. Silt, low plasticity [TOPSOIL]. Graphic Symbol Water Level Moisture Cond. Consistency/ Density Index F Shear Vane Undrained Shear Strength Peak/Remolded (kpa) Scala Penetrometer Blows per 100mm Sandy SILT; yellowish brown. Low plasticity. Sand, fine, poorly graded, subrounded to subangular. 1.0 ALLUVIUM SM M F-H >> Becomes light yellowish brown with orange mottles at 0.8 m depth. 1.5 SILTSTONE SM Sandy SILT; interbedded light and dark yellowish brown layers. Low plasticity. Sand, fine, poorly graded, subrounded to subangular. H Depth of Excavation: 1.8 m Termination Condition: Practical refusal GEOSCIENCE TEST PIT LOG BLANK TEMPLATE.GPJ NZ MASTER DATA TEMPLATE.GDT 7/7/ Test pit met practical refusal on hard material at 1.8 m depth. Scala Penetrometer met practical refusal at 1.0 m depth. Standing water was not encountered.