Supervising Scientist Division

2. Environmental assessments of uranium mines (Other activities in the Alligator Rivers Region)

Supervising Scientist Annual Report 2004–2005

Supervising Scientist, Darwin, 2005
ISBN 0 642 24395 6
ISSN 0 158-4030

2.5 Other activities in the Alligator Rivers Region

2.5.1 Historical tailings adjacent to the Gunlom Road

During 2004–05, oss provided technical advice to assist Parks Australia North (PAN) manage the area (the tailings area) adjacent to the Gunlom Road where uranium mill tailings from historical mining and milling activities conducted in the 1950s and 1960s had been deposited. oss implemented a programme of inspections focusing on issues such as radiological protection, fire, weed and erosion control in accordance with the agreed protocol. These activities focused on the tailings area, which had been stabilised with a rock cover to minimise erosion in 2000, and the small compound nearby where contaminated soil from the side of the Gunlom Road had been placed in 2000. Both of these sites were well managed by PAN.

2.5.2 Rehabilitation of the South Alligator Valley uranium mines

Discussions with Traditional Owners were carried out during the reporting period by oss , PAN and NLC staff to update members on progress with the proposed rehabilitation works and proposed final containment locations. Discussions also included the intention to sample various locations along Rockhole Creek to determine the extent and location of contamination of the creek to assist in planning rehabilitation of Rockhole Mine, and the need to undertake further bioaccumulation work at contaminated sites within the South Alligator Valley.

Two locations within the valley have been identified as potential locations for a final containment site. During 2004, an agreement was reached with Traditional Owners to undertake shallow drilling at both of these sites at the South Alligator Village and the South Alligator Valley Airstrip. The bores are part of the investigative work required by ARPANSA prior to authorising a suitable containment location. These bores were drilled towards the end of September 2004. Continuous monitoring was installed to provide monitoring of water levels throughout the wet season when access issues restrict site availability. Further work will be required this dry season to determine groundwater quality and permeability of the regolith.

There was no further progress on actions from Part A of the South Alligator Rehabilitation Plan during the reporting period and it is unlikely that any works will occur before the 2005–06 wet season.

oss continued a programme of inspections of the Gunlom Road site and the container storage facility during the reporting period. All inspections have had satisfactory outcomes with the only required actions being vegetation management of each site to maintain access and minimise fire risk to infrastructure.

2.5.3 Exploration

The Office of the Supervising Scientist coordinated a programme of site inspections at exploration sites during 2004–05. These sites were in west Arnhem Land where Cameco Australia Pty Ltd is exploring for uranium.

During the reporting period the Office of the Supervising Scientist undertook the second of two site inspections at Cameco’s exploration sites for 2004. The inspection was conducted on 19 August 2004 and included representatives from OSS, NLC and DBIRD. The team visited the heli-drilling program operated out of the Myra Falls Camp (Figure 2.22), and also took the opportunity to inspect the campsite operations. There were no issues identified with the heli-drilling operations or the operations at the Myra Falls Camp.

On 23 August 2004 following the inspection, a fire occurred at one of the heli-drilling sites near the Myra Falls Campsite. Drillers using oxyacetylene set nearby grass alight with a spark whilst cutting drill rods. Back burning controlled the fire to within the area surrounding the rig. The next morning the fire appeared to have gone out apart from a few smouldering logs. The drillers left site and later that day returned for the night shift. They discovered the fire had flared up destroying the water pump and progressed away from the site. A flight over the affected area the next day showed the fire had extended up to 3 km west and 1 km north (Figure 2.23).

Cameco provided stakeholders with an investigation report shortly after the incident that contained recommendations for a number of corrective actions.

Figure 2.22 Heli-drilling pad in operation near Myra Falls Camp

Figure 2.22 Heli-drilling pad in operation near Myra Falls Camp

Figure 2.23 Extent of fire surrounding drill site as seen from the air

Figure 2.23 Extent of fire surrounding drill site as seen from the air