Supervising Scientist, Darwin, 2005
ISBN 0 642 24395 6
ISSN 0 158-4030
No new developments occurred at the Jabiluka site during the reporting period. The site is maintained as a passive discharge site under the long-term care and maintenance regime of management.
Planting of seedlings was undertaken on the former non-mineralised waste stockpile area prior to the 2004–05 wet season as part of a revegetation strategy and to reduce erosion from the site. A target density of between 250 to 400 stems per hectare was achieved, with the intent being to establish a Eucalyptus tetradonta woodland.
In general the site as a whole held up well throughout the reporting period with the only work required being minor post wet season works to sediment traps and the access road.
The site of the old Djarr Djarr camp continued to be used as storage for Jabiluka drill core. However, negotiations are currently underway to remove the core to Ranger and commence rehabilitation of the site. ERA is proposing to commence works in August/September 2005.
The site is continuing to be maintained as a passive discharge site. The Interim Water Management Pond (IWMP) (Figure 2.15) has a restricted catchment and is a net loser of water. The drainage contours of the rehabilitated former mineralised stockpile pad area have been modified to allow some runoff to enter the IWMP. This has been done to increase the water volumes in the IWMP so that during the dry season water does not have to be pumped from the potable water bore to maintain coverage of the pond liner at the base of the pond. The water level during the wet season reached a maximum depth of approximately 1 m in the pond.
Figure 2.15 View towards the former mineralised stockpile area and Interim Water Management Pond (Jabiluka, March 2005)
The original Jabiluka Radiation Management Plan was drafted for the development of the decline (underground workings) and did not account for the change of operation to a care and maintenance state. Since the new Jabiluka Authorisation took effect in July 2003, the statutory requirement of quarterly reporting of radiological monitoring data for Jabiluka has been removed. The new Authorisation only requires reporting of radiation monitoring data if any ground disturbing activities involving radioactive mineralisation occur on site. All the mineralised material that was stockpiled on site was returned to the underground workings between 18 August and 27 September 2003. No ground disturbing activities occurred in 2004–05 and no monitoring data for either employees or environmental areas were reported by ERA.
The mid term review, which is a follow up to the 2004 Annual Audit of the Jabiluka operation (reported in the 2003–04 Annual Report of the Supervising Scientist) was undertaken on 12 November 2004. The review team consisted of representatives of oss, NLC and DBIRD.
There were no Category 1 or 2 non-conformances identified during the May 2004 audit. Of the nine Conditional issues identified, all were reclassified as Acceptable in the review. The four Not Verified issues were also reclassified as Acceptable.
The objective of the audit was to determine compliance with the current Authorisation.
The scope included:
The procedure was the same as in previous years with the protocol being developed by the audit team to conform with the appropriate ISO standards and then submitted to ERA two weeks prior to the interview and site inspection.
The audit team identified only 1 non-conformance which was classified as Category 2 and related to the submission of the annual environment report after the statutory due date. There were three aspects accorded a Conditional status.
The Jabiluka Minesite Technical Committee met 6 times during the reporting period (Table 2.9).
|Date||Significant additional agenda items|
|18th October 2004||Environmental monitoring program, Mining Management Plan, Decommissioning of Djarr Djarr|
|1 December 2004||No new items|
|27 January 2005||Jabiluka Plan of Rehabilitation No. 8|
|30 March 2005||Jabiluka long term care and maintenance revegetation plan; proposed variation to the Jabiluka Authorisation to reflect changes to the environmental monitoring program; updated progress against environmental conditions of the Jabiluka EIS and PER.|
|29 April 2005||No new items|
|8 June 2005||Audit results|
Changes to, and approvals under, the Authorisation during 2004–05 are listed in Table 2.10.
|December 2004||Approval of Jabiluka Rehabilitation Plan No. 8|
|28 April 2005||Authorisation 0140-01 was succeeded by 0140-02 to allow for the rationalisation of water monitoring given the current status of the site being long-term care and maintenance and the reduced risk to the environment.|
There were no reportable incidents at Jabiluka during the year.
In accordance with the Jabiluka Authorisation, ERA is required to monitor a range of surface and ground waters on the lease and to demonstrate that the environment remains protected. Specific water quality objectives (criteria thresholds were described in Supervising Scientist Annual Report 2003–04) must be achieved. Each week during the wet season, ERA reports the water quality in Ngarradj (Swift Creek) to the major stakeholders (SSD, DBIRD, NLC). A detailed interpretation of water quality across the site is provided at the end of each wet season in the ERA Jabiluka Annual Wet-season Report.
In addition to the ERA programme, the Supervising Scientist conducts a routine environmental monitoring programme including chemical and physical properties in Ngarradj (Swift Creek). Key water quality data from SSD and ERA routine monitoring of Ngarradj are reported on the Internet at www.deh.gov.au/ssd/monitoring/ngarradj-chem.html. The highlights of the monitoring season are summarised below.
Toward the end of 2003 Jabiluka entered a long-term care and maintenance phase. Since the site poses a very low risk to the environment, the Supervising Scientist’s water chemistry monitoring program at Ngarradj was reduced to monthly sampling for the 2004–05 wet season, augmented by automatic recordings of turbidity and hydrological data at 6-minute intervals. DBIRD resumed the role of performing check monitoring at Ngarradj, also on a monthly basis, but offset by two weeks from the SSD program. These independent programs complement each other, providing an approximately fortnightly frequency of water sampling and a combined dataset to assess the water quality at Ngarradj. ERA continued to carry out monitoring on a weekly basis.
The first water chemistry samples for the Supervising Scientist’s 2004–05 wet season surface water monitoring program were collected from the Ngarradj downstream statutory compliance point on 6 January 2005 . ERA commenced monitoring at that site on the 29 December 2004, the day flow was first observed, and DBIRD commenced monitoring in the second week of January. The last samples were collected from Ngarradj on 10 May 2005, by ERA, shortly before flow ceased.
ERA, SSD and DBIRD data generally agree (Table 2.11), with values and trends similar to those seen in previous years measured again this season. The water quality was very good throughout the season with only one exceedance of the electrical conductivity (EC) and the magnesium guideline (Table 2.11) occurring.
|3.9–6.0||SSD/DBIRD||4.9||5.3||4.4 – 5.0||4.3 – 5.8|
|ERA||5.0||5.3||4.7 – 5.8||4.8 – 5.7|
|EC ( µS/cm)
|21||SSD/DBIRD||15||16||13 – 24||12 – 24|
|ERA||12||10||9 – 17||8 – 15|
|–||SSD/DBIRD*||0.5||0.8||0.3 – 2.2||0.6– 2.0|
|ERA||1.||2.||<1 – 6.||<1 – 7.|
|NO3 (as NO3 )
|1.26||SSD/DBIRD||<0.02||0.04||n = 1 only||<0.02 – 0.13|
|ERA||0.02||0.02||<0.02 – 0.38||<0.02 – 0.31|
|1.5||SSD/DBIRD||0.4||0.3||0.2 – 1.1||0.1 – 1.4|
|ERA||0.3||0.3||0.2 – 1.2||< 0.1 – 1.0|
|0.76||SSD/DBIRD||0.3||0.4||0.2 – 0.6||0.3 – 0.5|
|ERA||0.3||0.4||0.2 – 0.4||0.3 – 0.8|
|6.||SSD/DBIRD||0.007||0.010||0.005 – 0.025||0.006 – 0.019|
|ERA||0.011||0.012||<0.005 – 0.029||<0.005 – 0.029|
ERA data taken from the ERA Weekly Water Quality Report 5 July 2005; * SSD data laboratory data; pH & EC based on field data – the common measurement to all organisations; ‡ dissolved (<0.45 µm); A compliance limit applies to uranium, management guidelines apply all other parameters shown; ERA data n = 20, SSD & DBIRD data n = 1 – 8.
All other key indicators remained within limits/guidelines. Uranium remained less than 0.5% of the limit throughout the season (Figure 2.17), similar to previous years (Figure 2.16).
Figure 2.16 Uranium concentrations in Ngarradj since the 1998-99 wet season (SSD data 1998-99 to 2003-04, SSD & DBIRD data 2004–05 wet season)
Figure 2.17 Uranium concentrations measured in Ngarradj by SSD, DBIRD and ERA during the 2004–05 wet season
The water quality objectives set to protect the aquatic ecosystems downstream of Jabiluka were achieved providing assurance that the environment remained protected throughout the season.
Radium-226 ( 226Ra) results for the 2001–02, 2002–03 and 2003–04 wet seasons are very low in Ngarradj (Figure 2.18). The wet season median difference (explained in the earlier section ‘Radium-226 in Magela Creek’) shown by the solid line in the graph is very low for each season, indicating human health was not adversely affected by the presence of 226Ra in Ngarradj from the Jabiluka project. 226Ra results for the 2004–05 wet season will be reported in the forthcoming Supervising Scientist Report on the Surface Water Monitoring Programme.
Figure 2.18 Radium-226 activity concentrations in Ngarradj upstream and downstream of Jabiluka
The biological monitoring program for Jabiluka has ceased, commensurate with the low risk posed while the site is in long-term care and maintenance mode. The last sampling event took place in the 2004 dry season. Results from six-years (1999–2004) of fish community structure studies were reported in the 2003–04 Supervising Scientist Annual Report along with available results for macroinvertebrate community structures. Further work is still being conducted on the macroinvertebrates collected last year.
Although there were no activities reported at the Jabiluka site, the population group that may in theory receive a radiation dose due to future activities at Jabiluka are the 60 or so inhabitants of Mudginberri, a small community approximately 10 km south of Jabiluka. At Four Gates Rd radon station, a few kilometres west of Mudginberri, the Supervising Scientist has a permanent atmospheric research and monitoring station. Radon decay product (RDP) and long lived alpha activity (LLAA) concentrations are measured there on a monthly basis. In addition, radon gas is continuously measured at the station with radon data being recorded every 30 minutes.
Figure 2.19 shows the radon decay product and long lived alpha activity concentrations measured at Four Gates Rd radon station by eriss. Radon progeny and long lived alpha activity concentrations are very small and comparable with natural background levels.The average airborne radionuclide concentrations measured in 2004 would translate into an annual total effective dose, including natural background, of 0.46 mSv from RDP and 0.013 mSv from LLAA. Only a small fraction of these doses would be due to mine derived radionuclides.
Figure 2.19 Radon decay product (RDP) and long lived alpha activity (LLAA) concentrations measured at the eriss Mudginberri Four Gates Rd radon station