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There are more than 50 000 abandoned mines in Australia, where the industry has played a key role in development from the 1850s to the 21st century and where an estimated 10 000 000 000 tonnes a year of coal, metal and waste are still being excavated. As in other countries with a past history of mining, the associated land contamination and water pollution is costly to remediate. Despite regulations requiring a rehabilitation bond to be posted at the start of a mine's life, initial calculations tend to underestimate the eventual cost of remediation, financial success is by no means assured, three-quarters of mines in Australia having been closed prematurely or in an unplanned way while larger companies tend to sell small assets as they become less profitable, and there are lengthy time-scales of monitoring and maintenance to be considered. Canada's National Orphaned and Abandoned Mines Initiative (NOAMI), which provides support across federal and provincial jurisdictions, is benchmarked by British Columbia's systematic risk-assessment process, but in Australia the 2012 Minerals Resource Rent Tax to fund the rehabilitation of old sites was scrapped following a change of government., There are more than 50 000 abandoned mines in Australia, where the industry has played a key role in development from the 1850s to the 21st century and where an estimated 10 000 000 000 tonnes a year of coal, metal and waste are still being excavated. As in other countries with a past history of mining, the associated land contamination and water pollution is costly to remediate. Despite regulations requiring a rehabilitation bond to be posted at the start of a mine's life, initial calculations tend to underestimate the eventual cost of remediation, financial success is by no means assured, three-quarters of mines in Australia having been closed prematurely or in an unplanned way while larger companies tend to sell small assets as they become less profitable, and there are lengthy time-scales of monitoring and maintenance to be considered. Canada's National Orphaned and Abandoned Mines Initiative (NOAMI), which provides support across federal and provincial jurisdictions, is benchmarked by British Columbia's systematic risk-assessment process, but in Australia the 2012 Minerals Resource Rent Tax to fund the rehabilitation of old sites was scrapped following a change of government.

We report on the detection of giant pulses from the Crab Nebula pulsar at a frequency of 200 MHz using the field deployment system designed for the MileuraWidefield Array’s Low Frequency Demonstrator (MWA-LFD). Our observations are among the first high-quality detections at such low frequencies. The measured pulse shapes are deconvolved for interstellar pulse broadening, yielding a pulse-broadening time of 670 100 s, and the implied strength of scattering (scattering measure) is the lowest that is estimated toward the Crab Nebula from observations made so far. The sensitivity of the system is largely dictated by the sky background, and our simple equipment is capable of detecting pulses that are brighter than 9 kJy in amplitude. The brightest giant pulse detected in our data has a peak amplitude of 50 kJy, and the implied brightness temperature is 1031.6 K.We discuss the giant pulse detection prospects with the fullMWA-LFD system.With a sensitivity over 2 orders of magnitude larger than the prototype equipment, the full system will be capable of detecting such bright giant pulses out to a wide range of Galactic distances; from15 to30 kpc depending on the frequency. TheMWA-LFD will thus be a highly promising instrument for the studies of giant pulses and other fast radio transients at low frequencies.

Experiments were performed with prototype antenna tiles for the Mileura Widefield Array Low Frequency Demonstrator (MWA LFD) to better understand the wide-field, wide-band properties of their design and to characterize the radio-frequency interference (RFI) between 80 and 300 MHz at the site in Western Australia. Observations acquired during the 6 month deployment confirmed the predicted sensitivity of the antennas, sky-noise-dominated system temperatures, and phase-coherent interferometric measurements. The radio spectrum is remarkably free of strong terrestrial signals, with the exception of two narrow frequency bands allocated to satellite downlinks, and rare bursts due to ground-based transmissions being scattered from aircraft and meteor trails. Results indicate the potential of the MWA LFD to make significant achievements in its three key science objectives: epoch of reionization science, heliospheric science, and radio transient detection.