Aurecon New Zealand Limited Level 6 KPMG Centre 85 Alexandra Street Hamilton 3240 PO Box 487 Hamilton 3240 New Zealand T F E W +64 7 834 1565 +64 7 834 3527 [email protected]aurecongroup.com Project 241157 File 241157_PGAR_Rev0.docx 13 November 2015 Revision 0 Page 1 13 November 2015 Jeremy Miller Project Manager Nova Energy Level 15 95 Customhouse Quay Wellington Dear Jeremy RE: Proposed Nova Energy Waikato 300 MW Power Plant - Preliminary Geotechnical Appraisal Report 1 Project background Aurecon have been engaged by Nova Energy (the Client) to provide geotechnical consultancy services to support preliminary planning and concept design for the proposed 300 MW Waikato Power Plant, located approximately 500m to the west of Kawhia Road, SH39, Otorohanga (the ‘site’). The purpose of this report is to provide a ‘high level’ site-wide preliminary geotechnical appraisal to support master planning and conceptual design of options for the proposed development. The key elements assessed by the preliminary geotechnical appraisal include: The power plant building location Access Roads A & B 220kV overhead transmission line In order to prepare this report a desktop study and site inspection was undertaken to collate available and relevant information to identify and provide preliminary discussion concerning geotechnical hazards at the site which may impact the design and construction of the proposed development. Detailed geotechnical investigation and assessment will be required to support future design and construction. 2 Site setting 2.1 Site location and access The proposed development site is located within a single legal property boundary, legally defined as Section 75 B:L XVI Pirongia SD and owned by NEL Farms Ltd. The site is addressed 869 Kawhia Road, RD3, Te Raumoa, State Highway 39 (SH39). The land parcel covers a total area of 153 hectares, of which the proposed power plant will cover an area of 2 to 3 hectares. The power plant site is currently accessed from the south-east along farm tracks extending from Kawhia Road. The site is currently zoned as rural, under the Otorohanga District Plan. The power plant footprint is located approximately 500 m to the west of SH39 within the centre of the property. From the building footprint, proposed Access A extends back along the existing farm access track south-east towards SH39. Proposed Access B extends from the building footprint north along existing tracks and through paddocks towards SH39 in the northern corner of the property. The proposed transmission line route extends roughly south-west from the power plant building footprint towards existing transmission line which is located in the southwest corner of the site.
Transcript
Aurecon New Zealand Limited Level 6 KPMG Centre 85 Alexandra Street Hamilton 3240 PO Box 487 Hamilton 3240 New Zealand
13 November 2015 Jeremy Miller Project Manager Nova Energy Level 15 95 Customhouse Quay Wellington Dear Jeremy RE: Proposed Nova Energy Waikato 300 MW Power Plant - Preliminary Geotechnical Appraisal Report
1 Project background
Aurecon have been engaged by Nova Energy (the Client) to provide geotechnical consultancy services to support preliminary planning and concept design for the proposed 300 MW Waikato Power Plant, located approximately 500m to the west of Kawhia Road, SH39, Otorohanga (the ‘site’).
The purpose of this report is to provide a ‘high level’ site-wide preliminary geotechnical appraisal to support master planning and conceptual design of options for the proposed development. The key elements assessed by the preliminary geotechnical appraisal include:
The power plant building location
Access Roads A & B
220kV overhead transmission line
In order to prepare this report a desktop study and site inspection was undertaken to collate available and relevant information to identify and provide preliminary discussion concerning geotechnical hazards at the site which may impact the design and construction of the proposed development. Detailed geotechnical investigation and assessment will be required to support future design and construction.
2 Site setting
2.1 Site location and access
The proposed development site is located within a single legal property boundary, legally defined as Section 75 B:L XVI Pirongia SD and owned by NEL Farms Ltd. The site is addressed 869 Kawhia Road, RD3, Te Raumoa, State Highway 39 (SH39). The land parcel covers a total area of 153 hectares, of which the proposed power plant will cover an area of 2 to 3 hectares. The power plant site is currently accessed from the south-east along farm tracks extending from Kawhia Road. The site is currently zoned as rural, under the Otorohanga District Plan.
The power plant footprint is located approximately 500 m to the west of SH39 within the centre of the property. From the building footprint, proposed Access A extends back along the existing farm access track south-east towards SH39. Proposed Access B extends from the building footprint north along existing tracks and through paddocks towards SH39 in the northern corner of the property. The proposed transmission line route extends roughly south-west from the power plant building footprint towards existing transmission line which is located in the southwest corner of the site.
A review of the Institute of Geological and Nuclear Sciences (IGNS) geological map 1:250,000 for Rotorua, Sheet 5 (Healy et al, 1964) indicates that three main geological units are mapped within the property boundary, as shown on Figure 1 attached.
The Aotea Formation, primarily a sandstone unit with siltstone, limestone and greenstone sub-units is mapped in the western part of the site and corresponds with raised topography to the west of the main building footprint. This unit is described as ‘massive or banded, calcareous muddy sandstone and
sandy calcareous siltstone, commonly glauconitic, basal, flaggy or cross bedded’. The unit is Oligocene-aged (~28.5 Ma) and mapped as part of the large Te Kuiti Group of sedimentary rocks. The southwest most part of the transmission line is shown to be underlain by Aotea Formation.
The Ongatiti Formation, a Pleistocene-aged (~1.8 Ma) ignimbrite unit, is mapped within the central and eastern parts of the property. The ignimbrite is described as ‘compound, moderately to strongly
welded, vitriophyric pumice and crystal rich ignimbrite with abundant lithics’. The majority of Access Road A and the proposed transmission line are situated within areas of the site mapped to be underlain by Ongatiti Formation.
The northern corner of the site, in the vicinity of site streams, is mapped as Piako Subgroup. This formation is described as alluvial and colluvial deposits of silt, sand, gravel and pumice. These materials are described as ‘locally derived pumiceous clays, sandy clays and gravels’. The majority of the Power Plant and Access Road B are situated within areas of the site mapped to be underlain by Piako Subgroup alluvium.
Although not mapped, the geological units described above are is anticipated to be overlain by a capping layer (typically a few metres thick) of volcanic ash originating from the Taupo Volcanic Zone. The beds of local streams are also expected to be underlain by recent alluvial deposits associated with migration of stream channels.
2.3 Geomorphological setting
The site is located within a small valley on the boundary between two key geomorphological settings, the West Waikato Hills and Ranges to the east and the Waipa Basin to the west, as described by Edbrooke (2005). The Waipa Basin is described as a wide valley system formed by the Mangapu River, Waipa River and Mangaokewa Stream (and respective tributaries). The northern part of the basin is dominated by low rolling hills formed by volcaniclastic rich alluvium with locally higher hills formed over weathered basement greywacke (such as Aotea Formation). Wide alluvial valleys separate the hills.
The West Waikato Hills and Ranges is described as an area of dissected hills and ranges extending inland from the coast towards the Waipa Basin. In the area of the site, the dissected hills are formed over siltstone and sandstones of the Te Kuiti Group (Aotea Formation). The hills have a stepped profile of alternating steep and gentle slope escarpments. Numerous block falls are apparent along steeper slopes and active earth flows are common. Sinkholes and karst landscapes are common in areas underlain by limestone, although this is not anticipated to be an issue for the power plant site.
2.4 Hydrogeological setting
The site area comprises a large valley setting with a number of small streams, creeks and tributaries flowing north. This network of streams drain to the Waipa River which lies approximately 1.4 km to the north of the power plant building footprint. Of these streams, the Ongaruhe Stream flows along the eastern periphery of the power plant, with a smaller tributary stream flowing through the centre of the building footprint.
No groundwater bore information is currently available. It is expected that the groundwater will be relatively shallow below the valley floor, which sits at an elevation of ~32 m RL. It is expected that surface run-off will percolate quickly through free draining site soils and flow towards streams and creeks at the base of gullies. In addition to natural water courses, a series of drainage channels and ditches have been constructed within the valley floor in the vicinity of the proposed power plant.
2.5 Active fault database
A review of the GNS online active fault database on 10 November 2015 indicates the nearest active fault to be in exceedance of 80 km to the south-east and east of site.
2.6 Regional hazard mapping
The site is located within an area defined as a ‘Not Very Hazardous’ to ‘quite hazardous’ earthquake zone by the Waikato Regional Council. ‘Not Very Hazardous’ classification is defined by the WRC as being underlain by materials formed between 75 and 2.5 millions years ago and which include sandstone, siltstone, mudstone, coal measures, limestone and conglomerate. These materials are defined as being weak to moderately strong, containing volcanic rocks of various ages. Gravel materials are usually dense to very dense. Fine-grained rocks are prone to slumping and land sliding, especially if saturated or without vegetation.
The ‘Quite Hazardous’ classification is defined as materials formed less than 2.5 million years ago and are made up of ricer and marine terrace deposits, lignite, dune sand, pumice, alluvium and ignimbrite flows. These include unsaturated, slightly weathered, loose gravel ash and sand.
Areas of natural valley and lower elevation (which include the Power Plant and Access B) are identified by Waikato Regional Council as being within zones of likely flood hazard. It is noted that the mapping prepared by WRC does not represent a design flood event.
Aurecon’s Senior Engineering Geologist undertook a site inspection on Tuesday 3 November 2015. The purpose of the investigation was to inspect the current status of the site, and identify any key geotechnical constraints that will need to be addressed and/or managed through the design and construction process.
The inspection focussed on the four key features of the power plant concept design. As such, other parts of the property (including the proposed gas supply route shown on Drawing L001) have not been inspected in as much detail and may need to be revisited in the event specific structures or services are relocated.
A summary of the key observations made during the inspection is presented in Table 1. The location references for each key feature are shown on Figure 1, attached. Site photographs relevant to the inspection are also attached at the end of this document.
Table 1 Key site observations
Location Ref.
Photo Ref.
Location Comment
1 1 & 2 Access A Entrance to site through paddock raised approximately 1.5 m above Kawhia Road. Gentle slope to north-west across paddock to existing farm track. No structures present, other than water tanks and a corrugated tin shed. A small grassed drainage channel (less than 500 mm deep) runs through the centre of the paddock along the rough alignment of Access A. Some exposed ash soils within paddock comprising stiff sandy silt. A cut would need to be formed to tie in access track to main road.
2 3 - 5 Access A Access A alignment runs along crest of sloping ground located at head of large gully. Slope approximately 15 to 20 m high and moderate to steep gradient (~°45). Small shallow failures noted to be present at top and base of slope exposing ash soil within fresh scarp surface. A small slip scarp was observed at top of gully head which was circular in shape and measured 2 m across and 400 mm high. Scarp at base of slope appears to be erosional. A small spring was observed at base of slope with swampy vegetation and organic silt/clay infilling the gully floor.
3 6 Access A Pond formed by earth embankment in base of gully with small culvert draining to stream.
4 7 & 8 Access A Access A follows alignment of existing farm track in this locality Track formed in cut located two thirds up the way of moderate north-facing slope. Slope ranges in height between 10 m and 20 m. Cut surface above track approximately 70°, exposing cream and pale brown sandy silt ash soils. Some minor instability caused by weathering and erosion in face, which is not vegetated. Slope above cut less than 30° with no instability observed. Below the track the slope steepens to between approximately 40° and 45°. Slopes below the track show some minor instability and erosion (stream located directly at toe of slope).
5 9 Power Plant
Power Plant building platform located in the base of an alluvial valley (Piako Subgroup) approximately 350 m wide. The northern end of the platform comprises level ground, but with natural undulations and hummocky surface. The site area is currently in pasture with no building structures. No soil exposures were observed.
Southern end of the power plant building platform is located over a plunging ridgeline (Ongatiti Formation) elevated approximately 5 to 10 m above the valley floor. The ridgeline trends south to north and drops into the valley floor at a gradient of ~<10°. Gentle to moderate slopes to east and west from crest of ridge with no observed evidence of instability.
7 12 Power Plant
The Ongaruhe Stream runs along the eastern boundary of the Power Plant building platform. At this location the channel is approximately 1 m to 2 m wide and 3 m deep and at the time of inspection running with approximately 1 m of water. Some minor erosion instability is observed at the edge of the channel. Channel is unlined and appears to follow a natural alignment.
8 13 Power Plant
Stream channel located through the western side of the building platform. Channel is 1 to 2 m wide. Channel approximately 1 m deep and half full. Channel unlined but has been straightened for drainage purposes.
9 14 & 15
Access B From the power plant, Access B follows the existing farm track north for approximately 300 m. The track follows the eastern edge of the valley floor at the toe of gentle to moderately sloping ground. At location 9, the track is formed within a small cut into a west facing slope with a gradient of ~25°. No evidence of instability observed.
10 16 Access B Culvert beneath existing farm track for small drainage channel.
11 17 Access B At the closest point to Access B, the Ongaruhe Stream flows through a natural cut approximately 3 m high and with a gradient towards the channel of approximately 40° to 60°. At the base of the cut, the channel is approximately 3 to 4 m wide and approximately 1 m deep.
12 18 Access B The northern end of the Access B deviates from the existing farm track and passes through paddock towards an entry point to be formed in the northern corner of the property. The alignment rises up a gentle slope at a gradient of approximately 10°.
13 19 Access B Where Access B meets the State Highway the elevation matches that of the valley floor. Between Locations 10 and 12 there is a small shallow plunging ridgeline through the alignment that could be avoided by re-routing the access way approximately 20 m to the north.
14 20 Proposed 220 kV line route
The proposed route of overhead wires follows a small gully to the south of the power plant footprint for approximately 450 m. Through the base of the valley the gradient to the south is gentle, with level to gently sloping topography to the east of the line route, and moderately sloping topography to the west of the line route. Further upgradient to the west, the slopes steepen sharply and show evidence of instability.
15 N/A Proposed 220 kV line route
Due to recent rain and steep topography this area could not be accessed directly, however from this point the line route moves to the south-west and traverses steep south-east facing sloping ground with evidence of instability visible in aerial photography.
2.8 Previous and current investigations
To our knowledge there has been no site specific geotechnical investigations undertaken at the site. Aurecon are in the process of undertaking ground investigation to support a large industrial
development located at the corner of Kawhia Road and Waitomo Valley Road, approximately 10 km to the south of the site. Although the location of the investigation is of reasonable distance from the current site, the site is located within a similar geological and geomorphological setting; within a low lying valley floor setting at the edge of the Waipa River catchment. A geotechnical assessment report is yet to be published by Aurecon, however the following information has been obtained which is of relevance to this site:
MASW geophysics undertaken at the Kawhia Rd site confirmed a Subsoil Class C setting in accordance with NZS1170.5. The geophysics also identifies the presence of buried palaeo-channels within the Piako Subgroup which may result in locally deep soft sediment or greater depth to bedrock.
Investigations undertaken to date confirm the presence of shallow topsoil and recent volcanic tephras overlying a thick sequence of Quaternary-aged alluvium, comprising primarily cohesive (silt) material with occasional horizons of sand and organic material.
The results of in-situ testing show an SPT N values of 0 to 10 within alluvial sequence improving to 30 – 50 in within weathered bedrock (estimated to be present below the site at approximately 20 m bgl).
The alluvial sequence was found to comprise soft and loose soils which are likely to be susceptible to settlement, low bearing capacity, and liquefaction risks.
3 Engineering considerations
3.1 Introduction
The desktop information indicates the site is underlain by two main geological units which are likely to govern the geotechnical aspects of the development. The Power Plant and Access Road B is likely to be underlain by a sequence of quaternary sediments overlying bedrock at depth. Access Road A and the overhead transmission line is largely underlain by Ongatiti Formation. All of the areas are expected to be underlain by a capping layer of topsoil and ash of variable thickness. Key geotechnical engineering considerations for development include the following:
Variability in ground conditions and soil flexibility (subsoil class)
Foundation conditions – bearing capacity and settlement risk
Seismic considerations including liquefaction and lateral spread risk
Slope stability risk
Earthworks and reuse of site soils
Environmental risk
Each of the above the constraints are discussed in more detail in the following subsections. These considerations are subject to change based on the findings of any future geotechnical or environmental investigations.
3.2 Preliminary ground model
Based on the mapped geology and the geophysical information obtained as part of the current scope, it is considered likely that the subsurface ground profile within the Power Plant and Access Road B will comprise a sequence of topsoil and volcanic tephras overlying alluvial material comprising sand, silt and gravel. The alluvial sequence will be underlain by the published mapped geological units (being either ignimbrite or sandstone). The alluvial layers may be separated by horizons of soft lacustrine silt
and clay and localised peat deposits. Access Road A is expected to be underlain by Ash mantling Ongatiti ignimbrite. The transmission line is expected to be largely underlain by Ash mantling Ongatiti Formation, with the possibility of Aotea Formation outcropping at the southwest end of the proposed alignment.
Based on recorded groundwater levels, topographic information and proximity to surface water bodies it is anticipated that a permanent groundwater table will be less than 5 m below the ground surface level within the area of the Power Plant and Access B. It may be possible that a shallow or perched water horizon exist as a result of surface run off from the adjacent hills.
There is currently no evidence of fill material within surface, or near surface soils, however this cannot be ruled out. Any non-engineered fill is likely to be unsuitable for earthworks or bearing shallow foundations without investigation of its properties, or information regarding fill compliance testing becomes available.
3.3 Site classification
Based on the mapped geology it is considered likely that the area of the Power Plant building footprint will meet the requirements of a Class C or D site in accordance with NZS1170.5:2011 Earthquake
design actions. This will need to be confirmed by geophysical or geotechnical ground investigations. The transmission line is expected to be Class C but potentially may be Class B where shallow rock is identified during investigations.
3.4 Foundations
3.4.1 Power Plant
There is potential for soft or organic soils to be present within alluvium near the surface within the area of the power plant building footprint and along Access Route B. These soils may be susceptible to consolidation settlement beneath shallow foundations supporting high building loads and where earth fill embankments are proposed. Where significant cuts are undertaken to form building platforms, the risk of settlement may be reduced through load compensation.
The presence and extent of soft soils shall be investigated by geotechnical investigation with analyses undertaken based on final landform design and expected building loads and embankment heights. The risk of consolidation settlement may be reduced or mitigated through one or a combination of the following:
Undercut and replacement (where practicable to remove shallow compressible soils near surface)
No information has been provided in respect of building foundations or finished design levels. The base of the valley through which the Ongaruhe Stream flows, and the location of the power plant, may be underlain by topsoil and soft silt or loose sand alluvial material with pockets of organics. Soft cohesive material or loose granular material may result in a lower bearing capacity for shallow foundations. Conversely, even if relatively stiff soils are present, heavy and concentrated building loads may exceed available bearing capacities for these soils and therefore require investigation, specific foundation design and/or ground improvement.
Foundations for the pylons are expected to comprise either pads or piles. The foundation conditions are expected to comprise ash overlying Ongatiti Fm. Where practicable the foundations will be embedded into the Ongatiti Formation.
The foundations for the transmission line are likely to be situated on or near sloping ground which may be susceptible to or situated within areas of slope instability and erosion. Based on the assumption that the proposed transmission line is located largely outside of the mapped alluvial basin, consolidation settlement is unlikely to be a significant risk. The likely factors governing foundation design will be the site stability, and the foundation bearing capacity, and elastic settlement limitations for the pylons.
3.5 Liquefaction hazard
Given the presence of quaternary alluvial sediments and elevated groundwater conditions, it is considered likely that soils underlying the Power Plant are susceptible to liquefaction-induced settlement in the event of a design event earthquake. It is anticipated that the power plant, given that it is a critical lifeline or service, will be an Importance Level 4 or 5 structure in accordance with NZS1170.0:2011. It is very possible that liquefaction will result in unacceptable settlements across the power plant footprint as a result of design level earthquake events. A detailed assessment of liquefaction will need to be assessed through site specific ground investigation and subsequent geotechnical analysis.
Options to mitigate or manage the effects of liquefaction are available and are similar in nature to those proposed for managing settlement risk (i.e ground improvement, foundation strengthening) and therefore is it anticipated that the foundation system for the power plant is likely to be designed to mitigate multiple geotechnical hazards including consolidation settlement, low bearing capacity and liquefaction hazard. It is considered that the site is at low risk from lateral spreading hazard due to the limited depth and small size of adjacent stream channels.
3.6 Slope instability
Hills to the west/southwest of the Power Plant comprise areas of steep sloping ground rising approximately 80 m above the valley. These slopes are of moderate to steep gradient with some vegetation but evidence of instability (scarps or bluffs) is observed.
The risks associated with slope instability are best managed by relocating structures and roads away from instability areas. If however this is not practicable then options for stabilisation may include the following:
General slope stabilisation measures:
Slope re-profiling
Installation of drainage and erosion protection (vegetation and geotextiles)
In combination with general slope stabilisation measures, where there is a risk of debris inundation from slips above a road or structure then the following options are available:
Debris bunds and catch fences
Retaining walls
Soil and rock stabilisation – soil nailing, rock bolting
In combination with general slope stabilisation measures, where there is a risk of under slip below the edge of a road or foundation/structure then the following options are available:
Construct deep (pile) foundations
In-ground walls and or retaining walls
The transmission line route is situated within an area of slope instability risk which may impact the location of and type of foundation proposed for the pylons, potentially on a foundation location specific basis. Geomorphological mapping in the proposed alignment area will be important to identify appropriate locations to put foundations which limit the risk posed from slope instability. This will be followed by site specific geotechnical investigation to inform foundation and slope stability design.
The alignment along Access Area A is located near to the crest of sloping ground and formed within cuts. There is potential for slope instability to cause washouts from below the access road, or for inundation from above (Photo 7 provides an example of this situation). Ground investigation and topographic survey of key slopes will be required to inform quantitative slope risk modelling to better assess risk of instability along access ways.
Alternatively, if it is possible to reroute Access A away from sloping ground (recommending a horizontal distance measured from the toe of offending slopes of three times the slope height) this may limit need for more detailed investigation and quantitative analyses. Stability of existing tracks may be improved through use of drainage, sealing the track surface and/or retaining walls.
3.7 Surface water and groundwater
A number of small streams are located within the valley floor that may need to be realigned and/or culverted to redirect flow away from building areas. By re-aligning Access B it may be possible to make use of existing culverts constructed below the farm access.
It is considered likely that any excavations to form shallow foundations or basements within the power plant building footprint will intercept the groundwater table. This may require implementation of appropriate drainage, dewatering and/or the use of drawdown wells.
Drainage measures are likely to be required for areas of instability where this is effecting infrastructure in order to limit the risk of erosion caused by overland flow and groundwater seepage.
3.8 Earthworks
Any non-engineered fill or material with high organic content (such as peat) identified by ground investigations will not be suitable for re-use as engineered fill. This material may be suitable for pre-loading or landscaping. Any non-engineered fill may need to be tested from environmental perspective to confirm ongoing suitability for re-use on site. It is anticipated that site won natural ash soils will be suitable for re-use as engineered fill for bulk earthworks landform modification subject to appropriate testing. Imported granular fills are likely to be required for site drainage, roading pavements and to form building foundations.
3.9 Environmental
The site is an operational dairy farm, and is expected to have remained as such for much of its developed history. Dairy farms are not formally recognised by the Ministry for Environment (MfE) on the Hazardous Activity and Industry List (HAIL) with potential to cause soil and groundwater contamination. However it is recognised that dairy pasture within the Bay of Plenty and Waikato regions have been widely sprayed with phosphate-based fertilisers that have resulted in gradual accumulation of heavy elements such as arsenic and cadmium that often exceed the ‘background’ concentration set by regional councils.
These elevated concentrations are not likely to be anywhere near human health soil contaminant standards set by the NES (for commercial/industrial land use) or relevant ecological screening criteria. As such the on-going risk associated with pasture to human health and environment is considered to be low. Elevations above background do not meet the MfE definition of cleanfill, and as such, any off-site disposal of site soils should be undertaken in liaison with Waikato Regional Council.
The presence of additional contaminating activities beyond pastoral land use at the site has not been assessed to date. A more detailed assessment of contamination issues may be required by Otorohanga District Council to be assessed under the National Environmental Standard for Assessing
and Managing Contaminants in Soil to Protect Human Health Regulations (2011) as part of any future land use or building consent application.
3.10 Further investigation
In order to support specimen and detailed design, extensive ground investigation will be required to provide further analysis of geotechnical hazards and provide parameters for design. We recommend a phased approach to investigation:
Non-intrusive geophysical investigation comprising MASW across the proposed Power Plant footprint. The purpose of this investigation would be to provide low cost non-destructive investigations over a wide area to confirm likely depth of bedrock, identify any key risk areas requiring more targeted investigation (palaeochannels, obstructions, low density ground); and provide classification of sub-soil class (in accordance with NZS1170) early in the design process. This could be supplemented with some limited ground investigation to confirm interpretation of MASW and provide more detailed observations of ground conditions to support specimen design.
Included within this phase would be a geomorphological mapping exercise to identify areas of slope instability which will inform our recommendations for the roading alignments and foundation locations for the transmission line pylons. The geomorphological mapping will be supported by LIDAR and detailed instrument survey of key risk areas
Once design is further advanced, detailed geotechnical investigation at the locations of the key design elements will be required to support design. The following investigations could be expected:
Power Plant building: rotary boreholes, Cone Penetration Tests (CPT) and shallow investigations (test pits or hand augers) to inform liquefaction and settlement analyses; earthworks and foundation design.
Access A: machine drilled boreholes and shallow investigations (test pits and hand augers) to inform earthworks, slope stability analyses and design of civil infrastructure.
Access B: Shallow investigations (test pits and hand augers) to inform earthworks and design of civil infrastructure.
220 kV transmission line: boreholes at the location of each pylon platform to inform slope stability analyses and foundation design,
Please do not hesitate to contact the undersigned should you wish to discuss any of the above further. Yours sincerely
Aurecon has prepared this report in accordance with the brief as provided. The contents of the report are for the sole use of the Client and no responsibility or liability will be accepted to any third party. Data or opinions contained within the report may not be used in other contexts or for any other purposes without Aurecon’s prior review and agreement.
Soil and rock formations are often variable, resulting in heterogeneous distribution of contaminants across a site. Contaminant concentrations may be estimated at chosen sample locations, however, conditions between sample sites can only be inferred on the basis of geological and hydrological conditions and the nature and the extent of identified contamination. Boundaries between zones of variable contamination are often indistinct, and therefore interpretation is based on available information and the application of professional judgement.
Only a finite amount of information has been collected to meet the specific 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 judgment and it must be appreciated that actual conditions could vary from the assumed model.
This report does not provide a complete assessment of the environmental status of the site, and it is limited to the scope defined herein. Should further information become available regarding the conditions at the site, including previously unknown likely sources of contamination, Aurecon reserves the right to review the report in the context of the additional information.
This report has been prepared for the Client for its own use and is based on information provided. Aurecon takes no responsibility and disclaims all liability whatsoever for any loss or damage that the Client may suffer as a result of using or relying on any such information or recommendations contained in this report, except to the extent Aurecon expressly indicates in this report that it has verified the information to its satisfaction. This report is not to be reproduced either wholly or in part without our prior written permission
Photograph 19 Looking north towards Access B site entrance from SH39 (Location 13)
Photograph 20 Looking south along lower reaches of proposed 220 kV route (Location 14)
CLIENT
WAIKATO POWER PLANT
DATE
TITLE
REVISION DETAILSDATEREV APPROVED
CHECKED
APPROVED
PROJECTDRAWN DESIGNED
241157PROJECT No.
SCALE SIZE
DRAWING No. REV
A3
075 150 300m
SCALE 1:7500
SITE LOCATION PLANSHEET 1 OF 2 L-001 4
AS SHOWN
PRELIMINARYNOT FOR CONSTRUCTIONT.NICKLESS B.McHARDY
R.CATHCART
C. Walters0 03.04.14 Issued for Comment C. Walters1 04.04.14 Revised for Comment C. Walters2 22.10.14 ISSUED PROJECT DESCRIPTION C. Walters3 19.12.14 ISSUED TO CLIENT C. Walters4 30.10.15 ISSUED FOR RESOURCE CONSENT C.Walters
220kV TMI-HLY
PROPOSED SITE~3.92 Ha
ACCESS A
VECT
OR G
AS
SH31
KAWHIA
ROAD
PROP
OSED
220k
VLIN
E RO
UTE
MAUI
GAS
WAI
PA R
IVER
PARCEL AREA152.75 Ha
SH31
KAW
HIA
ROAD
ACCE
SS B
GAS SUPPLY220m
176m
REFER TO DETAILEDSITE PLAN L-003
Ongatiti Formation
Aotea Formation
Piako Subgroup
Walton Subgroup (Puketoka & Kara
Holocene alluvium
KAW
HIA R
OAD
Projection: NZTM Site Location Plan300 MW Waikato Power Plant Preliminary Geotechnical Appraisal Report°
10/11/2015 0Version:Date:
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Notes:
1. Image dated 2011 and sourced from the LINZ Data Service ( https://data.linz.govt.nz/layer/1872-waikato-05m-rural-aerial-photos-2012-2013/) and licensed by Waikato Regional Aerial Photography Service (WRAPS) 2012 for re-use under the Creative Commons Attribution 3.0 New Zealand licence.
2. Location of proposed design elements approximate only.
LegendLegal property boundariesSection 75 Block XVI PirongiaSDPower Plant SiteAccess AAccess BProposed 220 kV Line RouteState Highway 39Ongaruhe StreamTributaries
