The unique method of iron sands mining undertaken at the New Zealand (NZ) Steel Mill, produces an inert waste sludge comprised primarily of clay and iron-sands/grit. This wet sludge waste is landfilled in cells to heights up to 25m. The purpose of this paper is to characterise the sludge waste and to investigate its potential for liquefaction. This paper presents an investigation of the sludge in the existing landfill based on in situ and laboratory testing. Design parameters such as shear strength, and pore water pressure are developed and confirmed for the sludge material. Liquefaction potential of the sludge due to earthquake shaking is investigated using a CPT-based assessment and Atterberg limits test results. The paper concludes with a discussion of liquefaction potential and recommended total stress and effective stress parameters for detailed design of a new landfill development.

This paper provides data on the chemistry of typical Australian leachates, from both putrescible and solid inert waste landfills, and examines the key determinants for deriving appropriate treatment methods. The paper discusses the process of reatment options development, including the use of field reatment trials, in typical Australian situations.

Concentrations of toxic metals (particularly lead, zinc, and arsenic) are present in painted concrete at the former Church College campus. This could preclude the classification of this material as ‘cleanfill’. This investigation has involved the development of a methodology by which painted concrete can be quickly and easily assessed in situ to determine whether or not it is likely to meet cleanfill criteria. Adopted portable XRF acceptance criteria have been developed for lead and zinc using a degree of conservativeness to account for variability and investigation uncertainty.

Whilst there is clear guidance on how to address asbestos in buildings, there is a serious gap in understanding when New Zealand Regulations apply to asbestos in soil. This paper examines when the following New Zealand regulations apply:

- Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations 2011 (the NES);
- Health and Safety in Employment (Asbestos) Regulations 1998 (H&S Regulations);
- Health Act 1956.

This paper provides a brief overview of the regulations, the application of which depend on whether there is a risk to human health. Determination of whether or not there is a health risk from asbestos in soil, in the context of the regulations, is then discussed.

The Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations, 2011 (the NES) is a national standard that applies throughout New Zealand to address human health effects from contaminated land. The regulations within the NES are relatively prescriptive, except for permitted activity Regulation 8(4). This regulation requires a Suitably Qualified and Experienced Practitioner (SQEP) to make a judgement on whether it is Highly Unlikely that there is a contamination risk to human health from an activity.
There is little guidance on how a SQEP should make an assessment of Highly Unlikely under Regulation 8(4). The purpose of this paper is to generate discussion of what Highly Unlikely means when assessing if the Regulation 8(4) conditions can be met for a particular activity on a site.