Tonkin and Taylor Ltd

Newmarket, New Zealand

Tonkin and Taylor Ltd

Newmarket, New Zealand
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van Ballegooy S.,Tonkin and Taylor Ltd | Wentz F.,Wentz Pacific Ltd | Boulanger R.W.,University of California at Davis
Soil Dynamics and Earthquake Engineering | Year: 2015

The liquefaction database describing the response of the Christchurch area in the 2010-2011 Canterbury Earthquake Sequence (CES) provides a unique basis for evaluating the regional application of various liquefaction analysis procedures, from liquefaction triggering analyses through to liquefaction vulnerability parameters. This database was used to compare the Robertson and Wride [17], Moss et al. [15] and Idriss and Boulanger [7] liquefaction triggering procedures as well as evaluate the impact of the 2014 versus 2008 Cone Penetration Test (CPT)-based liquefaction triggering procedure by Idriss and Boulanger on four liquefaction vulnerability parameters (SV1D, LPI, LPIISH and LSN), the correlation of those parameters with observed liquefaction-induced damage patterns in the CES, and the mapping of expected damage levels for 25, 100 and 500 year return period ground motions in Christchurch. The effects on SV1D, LPI, LPIISH and LSN were small relative to other sources of variability for the majority of the affected areas, particularly where liquefaction was clearly severe or clearly not. Nonetheless, considering the separation of the land damage populations as well as consistency between the events, the the IB-2008 liquefaction triggering procedures appears to give a slightly better fit to the mapped liquefaction-induced land damage for the regional prediction of liquefaction vulnerability for the Christchurch soils. The Boulanger and Idriss [1] triggering procedure produces improved agreement between the liquefaction vulnerability parameters and observations of damage for: areas south of the Central Business District (CBD) where there tends to be higher soil Fines Content (FC), and localized areas that experienced liquefaction during the smaller Magnitude (M) earthquake events. Implementation of the 2014 liquefaction triggering procedure for mapping of expected liquefaction-induced damage at 25, 100 and 500 year return period ground motions is shown to require use of representative Peak Ground Acceleration (PGA)-M values consistent with the de-aggregation of the seismic hazard. Use of equivalent magnitude-scaled PGA-M7.5 pairs, where the equivalency relates to previously published MSF relationships, with the 2014 liquefaction triggering procedure is shown to be unconservative for certain situations. © 2015 Elsevier Ltd.


van Ballegooy S.,Tonkin and Taylor Ltd | Wentz F.,Wentz Pacific Ltd | Boulanger R.W.,University of California at Davis
Soil Dynamics and Earthquake Engineering | Year: 2015

The liquefaction database describing the response of the Christchurch area in the 2010-2011 Canterbury Earthquake Sequence (CES) provides a unique basis for evaluating the regional application of various liquefaction analysis procedures, from liquefaction triggering analyses through to liquefaction vulnerability parameters. This database was used to compare the Robertson and Wride [17], Moss et al. [15] and Idriss and Boulanger [7] liquefaction triggering procedures as well as evaluate the impact of the 2014 versus 2008 Cone Penetration Test (CPT)-based liquefaction triggering procedure by Idriss and Boulanger on four liquefaction vulnerability parameters (S V1D, LPI, LPIISH and LSN), the correlation of those parameters with observed liquefaction-induced damage patterns in the CES, and the mapping of expected damage levels for 25, 100 and 500 year return period ground motions in Christchurch. The effects on S V1D, LPI, LPIISH and LSN were small relative to other sources of variability for the majority of the affected areas, particularly where liquefaction was clearly severe or clearly not. Nonetheless, considering the separation of the land damage populations as well as consistency between the events, the the IB-2008 liquefaction triggering procedures appears to give a slightly better fit to the mapped liquefaction-induced land damage for the regional prediction of liquefaction vulnerability for the Christchurch soils. The Boulanger and Idriss [1] triggering procedure produces improved agreement between the liquefaction vulnerability parameters and observations of damage for: areas south of the Central Business District (CBD) where there tends to be higher soil Fines Content (FC), and localized areas that experienced liquefaction during the smaller Magnitude (M) earthquake events. Implementation of the 2014 liquefaction triggering procedure for mapping of expected liquefaction-induced damage at 25, 100 and 500 year return period ground motions is shown to require use of representative Peak Ground Acceleration (PGA)-M values consistent with the de-aggregation of the seismic hazard. Use of equivalent magnitude-scaled PGA-M7.5 pairs, where the equivalency relates to previously published MSF relationships, with the 2014 liquefaction triggering procedure is shown to be unconservative for certain situations. © 2015 Elsevier Ltd.


O'Rourke T.D.,Cornell University | Jeon S.-S.,Inje University | Toprak S.,Pamukkale University | Cubrinovski M.,University of Canterbury | And 3 more authors.
Earthquake Spectra | Year: 2014

This paper explores key aspects of underground pipeline network response to the Canterbury earthquake sequence in Christchurch, New Zealand, including the response of the water and wastewater distribution systems to the MW6.2 22 February 2011 and MW6.0 13 June 2011 earthquakes, and the response of the gas distribution system to the MW7.1 4 September 2010 earthquake, as well as the 22 February and 13 June events. Repair rates, expressed as repairs/km, for different types of pipelines are evaluated relative to (1) the spatial distribution of peak ground velocity outside liquefaction areas and (2) the differential ground surface settlement and lateral ground strain within areas affected by liquefaction, calculated from high-resolution LiDAR survey data acquired before and after each main seismic event. The excellent performance of the gas distribution network is the result of highly ductile polyethylene pipelines. Lessons learned regarding the earthquake performance of underground lifeline systems are summarized. © 2014, Earthquake Engineering Research Institute.


Van Ballegooy S.,Tonkin and Taylor Ltd | Malan P.,Tonkin and Taylor Ltd | Lacrosse V.,Tonkin and Taylor Ltd | Jacka M.E.,Tonkin and Taylor Ltd | And 5 more authors.
Earthquake Spectra | Year: 2014

Christchurch, New Zealand, experienced four major earthquakes (Mw 5.9 to 7.1) since 4 September 2010 that triggered localized to widespread liquefaction. Liquefaction caused significant damage to residential foundations due to ground subsidence, ground failure, and lateral spreading. This paper describes the land damage assessment process for Christchurch, including the collection and processing of extensive data and observations related to liquefaction, the characterization of liquefaction effects on land performance, and the quantification of losses for insurance compensation purposes. The paper also examines the effectiveness of several existing liquefaction vulnerability parameters and a new parameter developed through this research, Liquefaction Severity Number (LSN), in explaining the observed liquefaction-induced damage in residential areas of Christchurch using results from 11,500 cone penetration tests (CPTs) as well as a robust regional groundwater model. © 2014, Earthquake Engineering Research Institute.


Pilgrim J.D.,Biodiversity Consultancy | Brownlie S.,De Villiers Brownlie Associates | Ekstrom J.M.M.,Biodiversity Consultancy | Gardner T.A.,University of Cambridge | And 8 more authors.
Conservation Letters | Year: 2013

Biodiversity offsetting is increasingly being used to reconcile the objectives of conservation and development. It is generally acknowledged that there are limits to the kinds of impacts on biodiversity that can or should be offset, yet there is a paucity of policy guidance as to what defines these limits and the relative difficulty of achieving a successful offset as such limits are approached. In order to improve the consistency and defensibility of development decisions involving offsets, and to improve offset design, we outline a general process for evaluating the relative offsetability of different impacts on biodiversity. This process culminates in a framework that establishes the burden of proof necessary to confirm the appropriateness and achievability of offsets, given varying levels of: conservation concern for affected biodiversity; residual impact magnitude; opportunity for suitable offsets; and feasibility of offset implementation in practice. Rankings for biodiversity conservation concern are drawn from existing conservation planning tools and approaches, including the IUCN Red List, Key Biodiversity Areas, and international bank environmental safeguard policies. We hope that the proposed process will stimulate much-needed scientific and policy debate to improve the integrity and accountability of both regulated and voluntary biodiversity offsetting. ©2013 Wiley Periodicals, Inc.


Gardner T.A.,University of Cambridge | Gardner T.A.,International Institute for Sustainability | Von Hase A.,Forest Trends | Brownlie S.,De Villiers Brownlie Associates | And 8 more authors.
Conservation Biology | Year: 2013

Businesses, governments, and financial institutions are increasingly adopting a policy of no net loss of biodiversity for development activities. The goal of no net loss is intended to help relieve tension between conservation and development by enabling economic gains to be achieved without concomitant biodiversity losses. biodiversity offsets represent a necessary component of a much broader mitigation strategy for achieving no net loss following prior application of avoidance, minimization, and remediation measures. However, doubts have been raised about the appropriate use of biodiversity offsets. We examined what no net loss means as a desirable conservation outcome and reviewed the conditions that determine whether, and under what circumstances, biodiversity offsets can help achieve such a goal. We propose a conceptual framework to substitute the often ad hoc approaches evident in many biodiversity offset initiatives. The relevance of biodiversity offsets to no net loss rests on 2 fundamental premises. First, offsets are rarely adequate for achieving no net loss of biodiversity alone. Second, some development effects may be too difficult or risky, or even impossible, to offset. To help to deliver no net loss through biodiversity offsets, biodiversity gains must be comparable to losses, be in addition to conservation gains that may have occurred in absence of the offset, and be lasting and protected from risk of failure. Adherence to these conditions requires consideration of the wider landscape context of development and offset activities, timing of offset delivery, measurement of biodiversity, accounting procedures and rule sets used to calculate biodiversity losses and gains and guide offset design, and approaches to managing risk. Adoption of this framework will strengthen the potential for offsets to provide an ecologically defensible mechanism that can help reconcile conservation and development. © 2013 Society for Conservation Biology.


Rogers N.,Tonkin and Taylor Ltd | Williams K.,Tonkin and Taylor Ltd | Jacka M.,Tonkin and Taylor Ltd | Wallace S.,Tonkin and Taylor Ltd | Leeves J.,Tonkin and Taylor Ltd
Earthquake Spectra | Year: 2014

The Canterbury earthquake sequence of 2010-2011 consisted of six main earthquakes directly affecting more than 300,000 people. The earthquakes caused land and building damage to more than 100,000 residential properties across Canterbury. This paper focuses on the issues related to liquefaction in the residential areas. There has been a need for coordination of specialist geotechnical advice into broader Government policy and planning recovery decisions, such as determining which land is suitable for rebuilding on and improving residential construction standards to increase future resilience. From a technical perspective, these earthquakes have provided a valuable opportunity to study the role that specialized engineering knowledge plays in the recovery process. A particular lesson is the importance of systematically capturing technical or factual information in the aftermath of a disaster, thereby planning beyond the short-term response to ensure that the right information is collected to assist the longterm recovery. © 2014, Earthquake Engineering Research Institute.


Pearson L.K.,University of Waikato | Hendy C.H.,University of Waikato | Hamilton D.P.,University of Waikato | Pickett R.C.,University of Waikato | Pickett R.C.,Tonkin and Taylor Ltd
Earth and Planetary Science Letters | Year: 2010

Global atmospheric sources of lead have increased more than 100-fold over the past century as a result of deforestation, coal combustion, ore smelting and leaded petroleum. Lead compounds generally accumulate in depositional areas across the globe where, due to low solubility and relative freedom from microbial degradation, the history of their inputs is preserved. In lakes there is rapid deposition and often little bioturbation of lead, resulting in an excellent depositional history of changes in both natural and anthropogenic sources. The objective of this study was to use sediments from a regionally bounded set of lakes to provide an indication of the rates of environmental inputs of lead whilst taking into account differences of trophic state and lead exposure between lakes. Intact sediment gravity cores were collected from 13 Rotorua lakes in North Island of New Zealand between March 2006 and January 2007. Cores penetrated sediments to a depth of 16-30cm and contained volcanic tephra from the 1886AD Tarawera eruption. The upper depth of the Tarawera tephra enabled prescription of a date for the associated depth in the core (120years). Each core showed a sub-surface peak in lead concentration above the Tarawera tephra which was contemporaneous with the peak use of lead alkyl as a petroleum additive in New Zealand. An 8m piston core was taken in the largest of the lakes, Lake Rotorua, in March 2007. The lake is antipodal to the pre-industrial sources of atmospheric lead but still shows increasing lead concentrations from <2 up to 3.5μgg-1 between the Whakatane eruption (5530±60cal. yr BP) and the Tarawera eruption. Peaks in lead concentration in Lake Rotorua are associated with volcanic tephras, but are small compared with those arising from recent anthropogenic-derived lead deposition. Our results show that diagenetic processes associated with iron, manganese and sulfate oxidation-reduction, and sulfide precipitation, act to smooth distributions of lead from anthropogenic sources in the lake sediments. The extent of this smoothing can be related to changes in sulfate availability and reduction in sulfide driven by differences in trophic status amongst the lakes. Greatest lead mobilisation occurs in mesotrophic lakes during seasonal anoxia as iron and manganese are released to the porewater, allowing upward migration of lead towards the sediment-water interface. This lead mobilisation can only occur if sulfides are not present. The sub-surface peak in lead concentrations in lake sediments ascribed to lead alkyl in petroleum persists despite the diagenetic processes acting to disperse lead within the sediments and into the overlying water. © 2010 Elsevier B.V.


Foster M.,Tonkin and Taylor Ltd. | Burke S.,Isthmus Group Ltd.
Australian Coasts and Ports 2015 Conference | Year: 2015

The coastal edge is a complex environment, where many different environments collide. For coastal practitioners, the same is true for the environment in which we work. The best outcomes are achieved where practitioners of all backgrounds and skill sets work together, alongside the community. The Onehunga Foreshore Restoration Project is an example of a multi-disciplinary approach achieving outcomes above and beyond those that could be achieved in a siloed approach. The Onehunga Foreshore Restoration Project has restored a more natural edge to the foreshore by creating 6.8 Ha new park land; three sand beaches, six gravel shell beaches, 11 headlands, a pedestrian and cycle bridge, and a boat ramp. Mana Whenua, the community, Auckland Council, Fulton Hogan, Tonkin & Taylor, Isthmus Group and AECOM worked together the deliver the design and construction of the new park. The focus of this diverse team was on providing a built environment that reflected the natural, cultural and human environment in which it sat. The boundaries of engineering, science, architecture, recreation and culture overlapped. This complexity was embraced and resulted in innovative and unexpected outcomes This paper describes some of the challenges and successes of the collaborative approach taken between the diverse team. The paper has considered views from designers, constructors, funders and members of the community for who the project was for.


Hunter R.P.,Tonkin and Taylor Ltd. | Bowman E.T.,University of Sheffield
Geotechnical Engineering for Infrastructure and Development - Proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2015 | Year: 2015

A new 'transparent soil permeameter' has been developed to study the mechanisms occurring during internal erosion in filter materials for embankment dams. The laboratory-based experiments utilise a novel approach where glass particles are used in place of soil, and an optically matched oil mixed with fluorescent dye is used in place of water. A technique known as Planar Laser Induced Fluorescence (PLIF) enables a two-dimensional "slice" or plane of particles and fluid to be viewed inside the permeameter, away from the permeameter walls via a laser sheet and captured by digital camera. During a test, fluid is passed through the solid matrix in upward flow, with the flow rate (therefore hydraulic gradient) being increased in stages until either internal erosion or bulk movement of the entire assembly develops. The results of one test, designed to replicate a sample from Skempton & Brogan (1994), are presented. In this test on an internally unstable material, clear migration of fine grains are visible within the sample under hydraulic gradients as low as ic = 0.25, whereas stable materials are expected to fail by heave at hydraulic gradients close to unity. The testing technique developed shows that optically matched glass and oil can behave similarly to soil and water materials as used in previous laboratory testing, and that the PLIF technique and image capturing has merit in understanding the mechanisms occurring during internal erosion processes. © The authors and ICE Publishing: All rights reserved, 2015.

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