CDM Smith (Australia)

Closure of mining landscapes is widely discussed within, and investigated by, the mining industry with increasingly innovative alternative uses found for open pits, underground workings, waste rock landforms, tailings storage facilities and water dams. When it comes to industrial and ancillary infrastructure though, many mining companies elect only to decommission and dispose of this infrastructure onsite. However, there is a growing need for efficient, effective and sustainable ways to find alternative purposes for these features, particularly in the face of increasing resource scarcity. The concept of ‘adaptive re-use’ is not new: it is common in the construction industry where re-use of materials and equipment is considered to be a win-win strategy, in modern communities, where recycling and even upcycling has become second nature, and in urban renewal, where there is a focus on repurposing of heritage buildings and other structures. Further, there is growing support for the ‘circular economy’ ethos, which favours careful management of resources and intelligent re-use of products and reconsidering the term ‘market’ more broadly. Many mining companies are now adopting a circular approach in selected areas of their business and while this is mainly focused on active operations, it is considered that there is an opportunity to extend this thinking to mine closure. However, identifying what materials can be ‘mined’ for re-use or repurposing can be challenging, partly due to obsolescence but also because of tenure restrictions, liability issues, transport costs, legal constraints and other factors. On this basis, the ‘5R Model’ has been developed to facilitate decision-making in relation to the alternative uses for industrial and ancillary infrastructure associated with mining and mineral processing operations. This paper outlines the basis of the 5R Model and the way in which this classification system can be used to guide investigations and decision-making for repurposing of industrial and ancillary infrastructure, including blue-sky options. Drawing on case studies on alternative closure scenarios for mining and mineral processing infrastructure and lessons learned from ‘urban mining’, this paper also discusses potential pathways to achieve these uses and facilitate custodial transfer of physical assets, and ways in which this model can also assist companies meet their waste minimisation, carbon reduction and other targets during closure of their sites.

Catchment-scale recharge and water balance estimates are commonly made for the purposes of water resource management. Few catchments have had these estimates ground-truthed. One confounding aspect is that runoff and soil-water inputs commonly occur throughout the year; however, in climates with strong dry seasons, base flow can be directly sampled. In an experimental catchment in the Mt. Lofty Ranges of South Australia, run-of-stream hydrochemical parameters were monitored. In this Mediterranean climate during the Millennium Drought (2001–2009), the stream was reduced to disconnected groundwater-fed pools. Two groundwater types were identified: (1) high-salinity type from meta-shale bedrock with thick, clayey regolith and (2) low-salinity type from meta-sandstone bedrock with sandy regolith. End-member mixing using silica and chloride concentrations and robust 87Sr/86Sr ratios reveal an apparent groundwater-flow paradox as follows. According to chloride mass balance and spatial distribution of hydrogeological units, the low-salinity groundwater type has seven times more recharge than the high-salinity type. Over the 28-year record, low-salinity groundwater contributed 25% of stream water, whereas high-salinity groundwater contributed 2–5%. During the drought year, however, annual stream flow from the high-salinity groundwater contributed 50%, whereas low-salinity groundwater contributed 18%. High-salinity groundwater dominated dry-season base flow during all years. The paradox can be resolved as follows: The meta-sandstone terrane drains quickly following wet-season recharge and therefore contributes little to dry-season base flow. Conversely, the meta-shale terrane drains slowly and therefore provides stream flow during dry seasons and drought years.

Quantifying the magnitude and timing of groundwater returns to streams from irrigation is important for the management of natural resources in irrigation districts where the quantity or quality of surface water can be affected. Deep vadose zones and perched water tables can complicate the modelling of these fluxes, and model outputs may be biased if these factors are misrepresented or ignored. This study was undertaken in the Murray Basin in southern Australia to develop and test an integrated modelling method that links irrigation activity to surface water impacts by accounting for all key hydrological processes, including perching and vadose zone transmission. The method incorporates an agronomic water balance to simulate root zone processes, semi-analytical transfer functions to simulate the deeper vadose zone, and an existing numerical groundwater model to simulate irrigation returns to the Murray River and inform the management of river salinity. The integrated modelling can be calibrated by various means, depending on context, and has been shown to be beneficial for management purposes without introducing an unnecessary level of complexity to traditional modelling workflows. Its applicability to other irrigation settings is discussed.

The Murray-Darling (MDB) Basin Plan is a strategic plan for the integrated and sustainable management of water resources, including groundwater. The MDB covers an area of more than 1 million km2 across five states and territories in south-eastern Australia. The major proportion of the groundwater extraction occurs over relatively small areas of alluvial aquifers, while the rest of the land area is characterised by sparse extraction from a wide range of groundwater systems. The Basin Plan follows a 20 year period of water reform and a major drought. While there had been a cap on surface water diversions, it is only with the advent of the Basin Plan that a limit has been set on the level of groundwater extraction across the MDB. Consistent management arrangements have also been applied across the MDB. Within the regionalised limits on groundwater extraction in the Basin Plan, localised impacts on the groundwater resource (including water quality, baseflow and ecology) will be managed through water resource plans. These plans will be developed and implemented by the five states and territories and accredited by the MDBA. The groundwater elements of the Basin Plan will be fully implemented in mid-2019, with a review in 2026. Future challenges include compliance, and adapting to climate change.

Resiliency of critical lifeline infrastructure has emerged as an important concern after recent disasters crippled the U.S. infrastructure and stranded many without basic utility services. System resiliency is often defined as the ability of the system to return to its original level of service in a short period of time. This paper will explore the six major dimensions of addressing infrastructure resiliency and will illustrate how these six dimensions can be utilized to develop a streamlined process of achieving infrastructure resiliency.

The FLASH code has evolved into a modular and extensible scientific simulation software system over the decade of its existence. During this time it has been cumulatively used by over a thousand researchers to investigate problems in astrophysics, cosmology, and in some areas of basic physics, such as turbulence. Recently, many new capabilities have been added to the code to enable it to simulate problems in high-energy density physics. Enhancements to these capabilities continue, along with enhancements enabling simulations of problems in fluid-structure interactions. The code started its life as an amalgamation of already existing software packages and sections of codes developed independently by various participating members of the team for other purposes. The code has evolved through a mixture of incremental and deep infrastructural changes. In the process, it has undergone four major revisions, three of which involved a significant architectural advancement. Along the way, a software process evolved that addresses the issues of code verification, maintainability, and support for the expanding user base. The software process also resolves the conflicts arising out of being in development and production simultaneously with multiple research projects, and between performance and portability. This paper describes the process of code evolution with emphasis on the design decisions and software management policies that have been instrumental in the success of the code. The paper also makes the case for a symbiotic relationship between scientific research and good software engineering of the simulation software.