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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. Source


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. Source


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. Source


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. Source


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. Source

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