| Moline | Rockhole | |
|---|---|---|
| Discovered | 1953 | 1954 |
| Operating Mine | 1956 to 1964 | 1959 to 1962 |
| Ore Processed | 128,000 tonnes | 13,155 tonnes |
| Average Grade U3O8 | 0.13 to 2.46% | 1.11% |
| U3O8 Produced | ~716 tonnes | 140 tonnes |
| Known Uranium Mines & Prospects | El Sherana, El Sherana West, Coronation Hill, Sleisbeck, Scinto 5, Scinto 6, Koolpin Creek, Palette, Saddle Ridge, Saddle Ridge East, Skull/Cliff Face, Rockhole-Teagues-Sterrets | |
The tale of the South Alligator uranium mining frenzy in the 1950's is remarkable, to say the least. Prospectors, share market speculators and companies wildly explored the region as fast as they could, making numerous discoveries of uranium ores at the surface. There was little regard for the traditional owners of the region, and any environmental concern was completely lacking. Every man and his dog was out to find their share of the uranium bonanza and get their subsidy from the federal government.
The Bureau of Mineral Resources (BMR) began exploration in the South Alligator region in the late 1940's, on the pastoral lease of Joe Callanan. A BMR geologist, Bruce Walpole, discovered a new uranium occurrence on June 2, 1953. Given that the day was the crowning of Queen Elizabeth II, the uranium deposit was aptly named Coronation Hill. This was quickly followed by a series of other important discoveries in the region, including the high grade El Sherana deposits 15 km further west of Coronation Hill, the Palette, Rockhole, Scinto series of deposits and the Sleisbeck deposit to the south-east on the Katherine River. The South Alligator region had now become a major uranium province within a matter of months, and the uranium frenzy reached unparalleled heights.
Two companies, United Uranium NL (UUNL) and South Alligator Uranium NL (SAUNL), were principally involved in the uranium mines in the area, each with its own treatment plant drawing upon ore from a total of 13 separate mines, of which 7 were open cut and 5 were underground mines. A total of over fifteen prospects were also worked in a north-west trending belt 24 km long and 3 km wide (3) (which would later become euphemistically known as the "Conservation Zone" amid a proposal for further mining at Coronation Hill, before being incorporated into Kakadu). There were also many speculative exploration companies formed, the most prominent of which was North Australian Uranium Corporation (NAUC), and often their share price would soar on the mere mention of a find of radioactivity, regardless of the size of the deposit or whether it was actually uranium (such as thorium).
One remarkable find was an 852 kg piece of massive pitchblende (uranium oxide, or UO2) from the El Sherana open cut, placed on display at the Australian Museum in Sydney (still ?) (14).
The total recorded production was estimated to be 874 tonnes U3O8 (3).
Map of the South Alligator Valley Uranium Field (9)
Click for larger, complete version (TIF file ~105 kb)
| Uranium Deposit Data in the South Alligator Uranium Field (4, 11, 12, 13, 14) | ||||||
|---|---|---|---|---|---|---|
| El Sherana | ||||||
| El Sherana West | ||||||
| Rockhole 1 | ||||||
| Palette | ||||||
| Saddle Ridge | ||||||
| Coronation Hill | ||||||
| Scinto 5 | ||||||
| Koolpin Creek | ||||||
| Skull | ||||||
| Sleisbeck | ||||||
| Scinto 6 | ||||||
| Saddle Ridge East 2 | ||||||
| Scinto 1 2 | ||||||
| Cliff Face 2 | ||||||
| Notes : OC - Open Cut; UG - Underground; O/U Combined Open Cut and Underground shafts. 1 - Including adjacent the Teagues, O'Dwyers, Sterrits sites. 2 - These sites have no production data recorded and are likely just exploration prospects. | ||||||
Coronation Hill Images (1)
(Click for larger versions)
 The Coronation Hill uranium mine, 1959. |
 Former Coronation Hill uranium mine, 1987. Left unrehabilitated for over 20 years. |
| Map of the inaptly named "Conservation Zone", 1990. The attempt to remine Coronation Hill was defeated. Shows location of old mines and Jawoyn Sickness Country. |
|
| Photos of Moline 1986 - Disaster In Progress (2) | |
|---|---|
 Moline tailings dump and derelict mill. Note breached bund wall and active gullying. (Click for large version) |
 Bank of Tailings Creek channel approximately 100 m downstream of lower bund. (Click for large version) |
| Radioactive Geologists | |
 George Sleis (left), who discovered 'Sleisbeck', and exploration partner Johnny Rosenweig (right). George was an ex-Czechoslovakian geologist with experience in uranium from the Russian WW2 military program. |
 Bruce Walpole - BMR geologist who discovered Coronation Hill in 1953. |
| Kakadu Map Click Here | |
| Detailed geographic map of the Kakadu region, link to map prepared by ANAWA. (Adapted from the Office of the Supervising Scientist 1993-994 Annual Report). | |
| Miscellaneous Photos - July 1999 (7) | |||
|---|---|---|---|
 Coronation Hill : the most sacred hill of the Jawoyn people. |
 The former tailings dump for the Rockhole mill - no tailings left, but still no recovery of the area either. |
 El Sherana Mining Camp sign "Est. 1955" - still here after all those years! |
 Heaps of junk still adjourns the Rockhole area. |
Adapted (mainly) from Chapter 6 (same name) from "The Uranium Hunters" (5).
George Sleis, a Czechoslovakian geologist with previous uranium mining experience under the Germans and Russians during World War II (for their respective nuclear weapons programs), was leading the North Australian Uranium Corporation field exploration teams in the Upper Katherine area. He was on a race against time as NAUC's share price was dropping steadily, and their field exploration teams were large and expensive. The horse support teams were in fact pulled out, leaving geologists and prospectors to go it alone. It was near the Arnhem Land border that George Sleis noticed a critical change of rock formation, indicating the possibility of mineralisation nearby. Together with exploration partner Johnny Rosenweig, they searched all day and found nothing.
However, the next day - June 23, 1954 - they struck rocks that sent the geiger counters right off the scale. A little chipping turned up the green of torbernite in the surface rocks with radioactive counts higher than anything previously found outside Rum Jungle. The surface counts were high and extended over such a wide area, that it seemed as though they had hit upon a major new uranium field.
George left Johnny to guard the find while he raced back to camp, leapt aboard the Landrover and drove 100 miles to the nearest telephone at Maranboy to break the news. Meanwhile, Johnny was roving the hills with his geiger counter, the only white man in eighty miles of wilderness, and turned up new radioactive lodes not far from the original strike with still higher surface counts.
Within a few hours of receiving George's jubilant telephone call, field manager Toby Becker to the air in his company's Auster, and flown 180 miles south to the NAUC leases on the Edith River, near Katherine. Geologist Harvey Newton, 24, who was in charge of the underground exploration at the Edith, knew nothing of his company's success on the Katherine until he saw the Auster roar out of the sky doing wing wobbles of victory.
Toby dropped a message instructing Harvey to drop everything and head for the new find on the Katherine by Landrover. All the men, plant and trucks on the Edith were to follow as as trucks could be loaded. Harvey was on the road in a matter of hours, and he drove through the night. Once past Eva Downs, he had trouble following the very faint trail, and somewhere upriver of the now abandoned Birdie Creek airstrip he became completely lost. With fuel supplies running low he drove desperately in a maze of river valleys, sandstone escarpments, thick bush and sandy creeks looking for the track. He was bushed for twenty-four hours before he found the trail, and roared into camp to join the lonely Johnny Rosenweig.
By that time, NAUC had launched a giant "Operation Sleisbeck". The new find was staked out under the name "Sleisbeck", coined from half of Toby Becker's surname, joined to George's as prefix. Stock exchanges reacted crazily to the brief announcement of a promising find on the Katherine. The shares rose from their low of twenty-five cents to a dollar in a few days, and continued to climb steadily, week by week.
When George and Johnny made their desperate, last-ditch search of the Upper Katherine, NAUC had paid up capital of $326,00, much of it spent. Within three months of the find, the shares were worth $6 million at peak value.
Within two months of the discovery of the Sleisbeck deposit, a road had been blazed through the wilderness, and trucks were now regularly carting in building materials. The road was not exactly a highway and only a North Australian driver would have attempted such a trip, loaded as the trucks were with heavy timber, iron and steel reinforcing, cement and food supplies. For more than eighty miles the track was littered with the debris left by bogged vehicles - broken tree trunks, mounds of earth piled where frantic drivers had dug out their wheels, sheets of battered new roofing iron used as track grips and then discarded, sticks and brush churned up in the clogging dust of what had become a hell trail.
At Sleisbeck itself, the bush had given way to rows of sturdy huts, mess buildings and workshops. Vehicles dashed about on newly-built gravel roads, and diesel-powered generators hammered day and night producing power. A Hungarian cook was serving lavish meals in a flyproof mess to more than fifty men already living in the field. It even had an airstrip, right alongside the mine. By odd coincidence, the uranium prospect was only a mile and a half from where a Dutch DC3 had crashed in the then unknown wilderness in 1946, and parts of it's crumpled wings still remained despite the amazing salvage operation. The crash site was actually a huge claypan, and it was quickly cleared and blasted with gelignite to create an emergency airstrip within a week of the uranium find by Toby Becker's ground teams. Supplies started flying in almost immediately.
The area was quite pleasant for living in, with numerous billabongs nearby providing good drinking water, swimming and excellent fishing. The local Aboriginal people, the Jawoyn, had left plenty of signs indicating that Sleisbeck had been one of their favourite spots. There were numerous caves with rock drawings (generally well hidden up in tiny isolated rock valleys on top of weathered limestone ridges), piles of ochred bones and Aboriginal "trinketry". Although the area was rich in Aboriginal history, they were not seen by the miners at this time. One look at what Toby Becker and his men had done to their hunting grounds was probably enough to send them scurrying deep into the Arnhem Land reserve.
However, the Sleisbeck "rush" was to prove a disastrous and costly mistake, as far as uranium production was concerned. The uranium, although extensive at the surface failed to continue at depth. Despite the tonnes of uranium ore mined at the site, only 3 tonnes of uranium oxide were actually produced (at the soon-to-be Moline Mill). The new uranium field was at first hailed as the most important strike outside Rum Jungle. Shares in NAUC soared to a record $4.95, but remained there only very briefly. Scores of speculators tempted by the sudden bonanza, "unloaded" in a hurry, and the share prices plummeted almost as fast as they'd risen.
Adapted (mainly) from the Chapter 9 from "The Uranium Hunters" (5).
Despite their intense but disappointing work at the Sleisbeck prospects, NAUC quickly shifted to airborne survey techniques, mainly through the work of John Newman. He had developed scintillometers for aerial surveys and he picked up possible new uranium lodes only thirty miles from Sleisbeck, in the rugged ranges of the South Alligator country. The discovery was not the first for the country. Copper had been found in the South Alligator early in the century, but never mined due to it's low grade and tremendous distances from markets killing probable profits. At the time, the nearest road was 64 miles away at Pine Creek - the Stuart Highway. Even during the gold rush, few prospectors had pushed this far into the wilderness.
The only people to move into the area were tough outback bushmen Billy Roberts and Joe Callenan. About 1949 Roberts and Callenan pegged a copper lease in a mountainous valley where the South Alligator Valley was walled in by 500-foot high sandstone bluffs, in places almost sheer. High up, nearly three-quarters of the way to the top of one valley wall, they found the bright blue-green stains of copper ore seeping from the motherrock. Roberts pegged the claim, in his and Callenan's name, calling it "Red Bluffs". He blazenly staked his claim, not believing it worth checking. Besides, no surveyor even came out to check the claim anyway. Who would dispute a claim on a remote South Alligator cliff face anyway ?
Roberts and Callenan sunk a shaft into the bright blue copper stains on Red Bluffs, and won a little ore. But there was no road to truck it out on, and no market anyway. They held the claim for several years, hoping that one day copper might boom enough to bring buyers into the Alligator country.
In 1953, a Bureau of Mineral Resources geologist, Bruce Walpole, drove into Callenan's "Plum Tree Camp" in a Landrover. He had a geiger counter, and wanted to explore the upper reaches of the South Alligator for possible uranium indications. Callenan agreed to go along as guide. When Walpole reached Red Bluffs, he climbed up to the lease with his geiger counter, and struck radioactive rocks high up on the face above the blue copper stains.
It was Coronation Hill Day, June 2, 1953. Bruce renamed the spot Coronation Hill, and a Government reserve of thirty-six square miles was clamped down over the region. Callenan and Roberts protested in Darwin Court and surveyors were finally sent to check their claim. In law there was only one ruling - they lost because it was found that they had pegged short. Their claim had to end where their last peg was staked, just short of the uranium lodes.
After a while, the government reserve was reduced to nine square miles around Coronation Hill. There was a spurt of activity for a while. The Bureau put up a camp at the foot of the cliffs, and geologists climbed the cliff faces, excavated drives and shafts, and made radioactive grid surveys. Then the wet season came, and the hills were abandoned to the rains and the kangaroos. The claim proved disappointing in terms of ore reserves, and for the next two years it was just a name and an indication that it might be worthwhile to seek uranium in the Alligator-Arnhem Land region.
The discovery of Sleisbeck focused new attention on the region, and sparked John Newman's aerial survey for NAUC. Three other companies, Northern Uranium Development NL, Uranium Mines NL and Uranium Development and Prospecting NL, also moved into the area and took out prospecting authorities.
NAUC originally had a prospecting area around Coronation Hill, but relinquished the authority on the discovery of Sleisbeck thirty miles away on the Katherine. Northern Uranium Development promptly applied for NAUC's relinquished area. Before the Court had granted the application, however, John Newman's airborne scintillometer picked up hotspots a few miles down river from Coronation Hill. Toby Becker immediately dispatched ground teams to find and peg the claims as quickly as possible. Technically, the region at the time was probably no-man's land. But the first company to peg a claim could well have the edge on any rival in a Court dispute.
The actual discovery was made for NAUC by a 66-year-old mining veteran, Queenslander "Pop" Daniels, and his mate Alan Hunt. They crawled over the craggy escarpments and corroborated Newman's airborne strikes on the ground on August 15 and 16, 1954. Toby Becker wasted no time once the find was reported. Landrovers roared over the faint trails from Sleisbeck, and fresh prospectors began an intensive combing of the South Alligator Valley.
About that time, Northern Uranium Development NL was merged with Uranium Mines NL, to form United Uranium NL. While NAUC was getting thoroughly entrenched on the Alligator, United Uranium's men were 1,000 miles away at the Mt Isa rush. Some were also standing by awaiting word of the granting of their application for the relinquished NAUC prospecting areas around Coronation Hill. By the time word leaked out that Toby Becker's men had already pegged new strikes on the Alligator, NAUC had established a base camp in the valley, begun to build a new airstrip, and pegged a whole new series of claims.
Frantic telegrams from Darwin brought United Uranium men racing north by Landrover and truck from Mt Isa. Among them was 48-year-old Jack G Smith, a copper miner who had fallen on hard times and had joined Northern Uranium Development as a paid prospector. Within a few days of his hurried departure from Mt Isa under the new United Uranium flag, Jack found himself encamped a few yards from a crocodile-infested river, in a land that was completely different from the barren country he knew around the Isa. His first job, along with other members of his team, was to hunt for NAUC's claims on the cliffs, and peg them.
The party made for the disputed ground with some anxiety, passing NAUC's camp on the way. Rumours were circulating that NAUC's men had been ordered to prevent them entering the disputed area, by force if necessary. But their orders were to peg, and they climbed the steep faces hoping there would be no trouble.
They soon found one of NAUC's datum pegs, solidly planted in the radioactive rock. They planted their own beside it and begun to hunt for the other pegs. A hail from a ridge, and they looked up to see two of NAUC's men, burly Mick Madigan and Pop Daniels, watching them with expressionless faces. Jack and his mates walked up to NAUC's men and explained their orders. Although they knew they might be trespassing, they must obey their own company's instructions. Both sides talked it out and came to amicable terms. Although servants of warring companies, they saw no reason for prospector-to-prospector animosity, and agreed to let the "legal eagles" settle the matter at Court. Jack and his mates spent the rest of the day double-pegging the rival claims, then returned to camp.
Word was later received that United Uranium had been granted it's application over the disputed ground, "subject to any leases, granted or applied for". Orders were given for the prospecting of new lodes on the company's area.
For two weeks they combed the craggy bluffs without finding a trace of anything. Then Jack made the strike of the year. He had been prospecting all day in high, steep gullies, and had arranged to meet his mate after dark at the mouth of Stag Creek, a tributary of the South Alligator. Just on dusk, Jack reached the summit of an almost perpendicular ridge to find his geiger beginning to tick wildly. He had only been using a geiger for about a month, but there was no mistaking the crazy tattoo in the earphones. As he walked along the ridge top, the ticking grew stronger and faster.
Tropical night was falling rapidly. Rather than be caught in darkness, he reluctantly retraced his steps and groped his way down the face to Stag Creek, where he told his disbelieving mate of the strike. They rushed back to report the find to their boss, geologist Ray Jones at the base camp.
Well before dawn the next day the team was heading for Stag Creek. The geigers began to tick as the prospectors reached the ridge top, and the counts grew wilder as they moved along the summit. Then, on an outcropping reef of brownish rock, all the geigers went right off the scale. The pegging got under way immediately.
They named the lease after the three daughters of Bluey Kay, one of the prospectors in the team with Jack Smith. By mixing the names Ellen, Sharon and Anna, they got the magical-sounding title of "El Sherana". Surface work on the lode began almost immediately, and the United Uranium camp was shifted to Stag Creek, at the foot of the ridge.
It needed only a few blows with a pick on the red-brown rock of the summit to reveal that El Sherana was fantastically rich at the surface - the richest strike on record up to that time. The rock was almost solid torbernite and autunite, and the reef stretched for more than 100 yards at the surface. News of the strikes sent uranium shares soaring yet again.
The valley was by now a hive of activity. Jeeps and landrovers from the rival companies were racing up and down the river. A party of Lands and Survey men were camped to survey the disputed leases. NAUC's bulldozers were blazing a new road down the valley from Sleisbeck, and enlarging the airstrip on which planes were already landing daily with men and supplies. At the El Sherana camp, a bulldozer was perched on an almost sheer hillside, tearing out a road up the bluff. Cheerful miners and geologists were hard at work on the new lode, which was getting richer with every shoveful of rock removed. Jack Smith watched his geiger-counter sing off scale over "nuggets" of bright yellow uranium ore chipped off the surface rocks. It was truly a fabulous find.
That night at the El Sherana camp, amid a luscious meal of buffalo, potatoes, pumpkin and onions, the talk was all uranium and the immense wealth to come from Alligator lodes. Nobody was even remotely pessimistic. A scientist from the British Atomic Energy Commission was a guest at the meal, visiting the camp on official and secret business. He could make no public comment, but he did say quietly that El Sherana was the richest surface uranium "show" he had ever seen. He'd been around the world. Over coffee he made the comment : "I wonder how long it will be before there are factory chimneys smoking in the Alligator ?" It seemed hard to visualize, but events proved the scientist right. El Sherana became one of the richest of the very lucrative chain of uranium mines along the South Alligator.
Based on Cull et al., 1986 (2).
The Northern Hercules mill, as it was originally known, or Moline as it became known during the uranium years, has a long history of metalliferous mining and ore milling. It began on a small scale during the 1890's, again in the 1930's and 1956-57. The most significant period of activity began in late 1959 when the mill at Moline was bought by United Uranium NL and commissioned for the production of uranium ore concentrates, although silver/lead/zinc and copper/gold ores were later treated at the site. It operated for 13 years until 1972, by which stage it had produced some 246,000 tonnes of tailings.
| Ore source and Type | Tonnes |
|---|---|
| Dolomitic silver/lead/zinc ore from Northern Hercules | |
| Gold sulphide ore from Mt Diamond | |
| Copper sulphide ore from Mt Diamond | |
| Uranium ore from various South Alligator valley mines |
| Uranium Ore Data for the Moline Mill (2) | ||||
|---|---|---|---|---|
(%) | (lb/t) | (Bq/kg) | ||
| Coronation Hill | ||||
| Saddle Ridge | ||||
| El Sherana | ||||
| Palette | ||||
| Scinto 5 | ||||
| Koolpin Creek | ||||
| Skull | ||||
| Total | ||||
| Note - assuming the uranium tailings are dispersed with the other tailings, an average Radium activity can be estimated as 34,500 Bq/kg. | ||||
The mill at Moline is situated at the head of the small (less than 0.7 km2) catchment of Tailings Creek which drains northwards to join Eureka Creek 1.3 km below the mill. Eureka Creek flows a further 4.8 km to it's confluence with Bowerbird Creek which in turn flows into the Mary River, approximately 20 km downstream of the mill.
During production there was neither the obligation nor incentive to provide effective long term containment of tailings. Equally, management techniques and containment technology were poorly developed. The slurried tailings were pumped onto the natural ground surface immediately downslope of the mill, and several earth bunds constructed to contain the tailings either leaked or were breached. These structures proved to be very short term containment measures and are now actively eroding along with the tailings. Part of the remains of one such bund, together with the derelict mill and active gullying on the main tailings dump are shown above.
The principal consequences of these management practices were firstly, that the dump dispersed downslope more than 1,000 m (from the mill) to cover about 17 hectares, and secondly, that by 1982, erosion had removed about 63,000 tonnes, or 25% of the original tailings mass. Some of the material washed from the dump has been deposited immediately downslope of the final bund. The photo above (right) shows the right-hand bank of Tailings Creek about 100 m downstream of the bund where more than 30 cm of tailings have been deposited. This deposition is a small proportion of the total tailings loss - the greater fraction of the eroded tailings has been washed downstream by Eureka and Bowerbird Creeks.
Some research was undertaken during the 1984/85 Wet Season to quantify the rates of erosion and release of radioactivity to the Mary River. Suspended sediment concentrations as high as 94 g/l were recorded in Tailings Creek immediately downstream of the eroding tailings pile. The total yield of sediment was equivalent to an erosion rate of almost 4 mm/year for the whole tailings area. Such an erosion rate is about two orders of magnitude (or 100 times) higher than natural rates in the Pine Creek and Jabiru regions. The erosion rates of the tailings have decreased, however, decreased perhaps by a factor 8 since the last bund was breached.
The radioactivity in the streams and sediments downstream of the mill can consistently be related to the deposition of eroded tailings sediment. The radioactivity is merely described as a convenient "labelling" in order to identify tailings sediment compared to natural or pre-mining sediment.
United Uranium NL negotiated a contract with the US Atomic Energy Commission for the sale of up to 200 tonnes of pitchblende ore and concentrate from the El Sherana mine. A concentrating plant began operation in October 1956 and some 150 tonnes of pitchblende concentrate containing 70 tonnes of uranium was produced in 1956-57 and was supplied through the Combined Development Agency. The residues from this, containing 1.15% U (or 1.5% U3O8), were sold to the AAEC at Rum Jungle.
In 1958 the two companies contracted with the UK Atomic Energy Authority for the supply of uranium oxide from the South Alligator mines.
United Uranium then purchased the North Hercules gold plant at Moline, 50 kilometres east of Pine Creek (and about 65 kilometres from the South Alligator mines) and started converting it for acid leaching and solvent extraction of uranium oxide with magnesia precipitation. The plant was commissioned with an annual capacity of about 130 tonnes U3O8 in May 1959, by which time there was a substantial stockpile of ore awaiting treatment.
South Alligator Uranium NL was meanwhile continuing underground exploration at its Rockhole prospect, and in 1957 United Uranium discovered the Coronation Hill uranium orebody.
In 1958 South Alligator Uranium commenced construction of a small (about 50 tonnes U3O8 per year) treatment plant at Rockhole Creek, using the same process as at Moline. This was commissioned in September 1959. However, it quickly filled its 118 tonne contract with UKAEA, so the mine was closed in 1961 and treatment of the stockpiled high-grade ore was completed soon after.
However, the Rockhole Creek plant was reopened in June 1962 for three months to produce 24 tonnes of uranium oxide for sale on the open market. The plant was then sold and partly dismantled. A total of 13,500 tonnes of average 0.95% U (1.12% U3O8) ore had been treated by the plant.
In 1963 United Uranium treated 15,000 tonnes of 0.69% U3O8 ore at Moline, a little over half from underground workings at the El Sherana West mine and the balance from open cut mines including Coronation Hill (mined 1957-1964). Exploration continued, but reserves were dwindling and the company purchased all the NT mining titles and the plant from the former South Alligator Uranium.
The Moline uranium plant finally closed in August 1964, having completed its A $10 million contract with the UKAEA involving the supply of 520 tonnes of uranium oxide. It had treated 128,000 tonnes of 0.30-0.58% U (0.35-0.68% U3O8) ore in a little over 5 years. (The plant was then converted to extract gold from the uranium tailings, and this finished in October 1965.)
Adapted from Waggitt, 1998 (9).
In 1964 the mining companies simply walked away and abandoned the different sites, which included open cut and underground uranium mines, a battery and gravity separation plant, gold separation and a small mill and solvent extraction plant. There was no legal requirement for site rehabilitation at the time, and companies have never paid a cent since walking away - taxpayers have since had to foot the bill, and rehabilitation remains incomplete due to government's refusal to fund full site cleanups.
The South Alligator Valley area remained in private ownership from 1964 until it was included in the Stage III Extension to Kakadu National Park in the mid to late 1980's. The Commonwealth made funds available for rehabilitation of most abandoned uranium mine sites in the Northern Territory, which included the South Alligator Valley mines as well as more "infamous" and lesser known sites such as Rum Jungle, Rum Jungle Creek South, Adelaide River and the Westmoreland/Pandanus Creek area near the Queensland border.
However, due to the lack of funds for major rehabilitation works across all sites, the program was restricted to minimum physical and radiological "hazard reduction" works only. After detailed surveys in 1986, proposals prepared in 1988 were finally put out to tender in 1990.
The rehabilitation program essentially consisted of fencing off open cut areas, diverting some roads away from former mine sites, earthworks to minimise further erosion problems, simple burial of contaminated or radioactive materials, dismantling of the old South Alligator mill, the erection of warning signs and concreting in custom made large diameter steel tubes to block off adit and shaft entrances.
However, earlier surveying work by the Australian Nature Conservation Agency (ANCA - the former government authority that managed national parks at the time) had identified two bat colonies in the some of the old workings at the South Alligator mines. Thus the grilles at two sites in the Rockhole complex and one site in the El Sherana area were thus modified to allow the passage of bats "whilst being effectively impossible for humans to pass through" (9). Though there may not be alternative caves for the bats, it would seem potentially dangerous for the bats to dwell in old uranium mine shafts - the long-term effects to these populations could alter them from the other bat colonies of the region, thus interfering with their natural evolution in a National Park (10).
The milling that occurred at the small South Alligator mill produced several tailings deposits, and in keeping with the devastating tradition of the 1950's-60's, the tailings were simply dumped on the nearest flat ground - that is, on the banks of the South Alligator River. In times of high floods the tailings were often washed away by a combination of flood and runoff waters.. In 1986 the majority of the tailings were excavated and trucked to Moline and reprocessed to extract remnant gold. However, small pockets of tailings still remained on site at South Alligator.
The old mill was dismantled and buried about 1.5 km east, close to the former township site. The disposal method was simply a trench dug by bulldozer. The wastes were simply dumped in the trench and included waste metal, remnant tailings, various structures and processing vessels. The site was cheaply covered with a minimum of 1.5 metres of soil, although no detail concerning the engineering design and construction of this cover was given in Waggitt (1998) (9). Thus there is no way of assessing the long term ability of the dump to contain the radioactive wastes buried therein.
After the completion of initial "hazard reduction works" more detailed radiological surveys were undertaken to determine whether the sites now presented minimal risks. The majority of the work was directed at gamma exposure levels, with some additional radon sampling. A few hot spots were found to remain, with radon levels suggested 4.6 mWL. Although this was below any concern level, further cleanup work was recommended and undertaken with closer supervision by Supervising Scientist staff, in particular at the El Sherana sites and the old mill site. The calculated radiation doses as calculated by Supervising Scientist are given below (9).
| Location | Gamma Dose Rate mGy.h-1 | Dose Rate Estimate for Full Time Occupancy mSv | |
|---|---|---|---|
| Min | Max | ||
| South Alligator Mill area | |||
| El Sherana Weighbridge | |||
| El Sherana Battery | |||
| Containment | |||
| Background | |||
The new hazard reduction works program was undertaken in May 1992. The same methodology was used, except only a minimum 1 metre cover of soil was used to backfill and cover trenches. During the work program, a further batch of radioactive materials were discovered within the confines of the El Sherana mining camp. These were treated in the same way and merely dumped in trenches. Further works were also carried out at the Airstrip anomaly and the Saddle Ridge open cut.
At the completion of the works, there were a total of five containment sites, the South Alligator mill and village site, the Airstrip site, the weighbridge site, the battery/bund site and the Saddle Ridge site. All of these sites are now prevented from any use in the future.
Annual monitoring is now undertaken by the Supervising Scientist Group, including radiation surveys, erosion and revegetation surveys.
The inspection in 1993 revealed that an erosion gully had developed upstream of the El Sherana camp containment site, extending across one corner and exposing scrap metal. Further remedial work was undertaken to control and re-engineer the site to prevent any further erosion. The 1994 inspection showed that erosion continued to be of concern despite previous remedial works, and a small sinkhole was developing at the Airstrip site. Further remedial works were again undertaken.
In 1995, settlement at the El Sherana camp site had resulted in a few small sinkholes and tension cracks developing. At the Battery/bund site the Eucalyptus seedlings were showing signs of stress, with the cause remaining unknown. Tension/subsidence cracks were also evident at this site, although they were ignored since erosion had been minimal at that point.
Although the initial soil cover placed over the waste dump sites, the long term safety of the radioactive wastes is far from certain :
- the water table in the valley varies from near surface during the Wet Season, to 10 m depth at the end of the Dry Season (13). This large fluctuation in the water table will continually pulse up and down through the dumps, introducing water and oxygen into the wastes. This enhances the potential for contamination leaking out of the dump sites, not to mention the problems of groundwater moving physically through the wastes.
- the pyrite content of some of the wastes is quite high - the Rockhole area had pyrite up to 2% (3). This will enhance the possibility of acid mine drainage, which can further leach heavy metals and radionuclides out of the wastes and contaminate groundwater or the nearby South Alligator River system.
Despite the obvious, Waggitt asserted that the "environmental impact of uranium mining activities in the South Alligator Valley was relatively low" (9). Such assertions are typical of the uranium industry - not independent scientists who are legally supposed to regulate and control uranium mining. Such promotion of myths continue to be made even in times of supposed modern environmental awareness.
General Notes - The uranium mineralisation across the South Alligator Valley was often found in a variety of rock types, but typically in faults, shears, breccias and joints close to the change between rock formations.
Rockhole Area - This consisted of three main concentrations of uranium, namely the Rockhole, Teagues and O'Dwyers deposits. The uranium was mainly extracted by underground mines. The gangue minerals or associated rocks included up to 2% pyrite, a little marcasite and chalcopyrite - famous precursors to Acid Mine Drainage (when the pyrite in the rock is exposed to water and oxygen at the surface, the pyrite can generate sulphuric acid. This dissolves toxic heavy metals and radionuclides which can devastate local environments - Rum Jungle is a famous example of such devastation).
El Sherana - The uranium in the El Sherana area is probably related to the major fault controlling uranium mineralisation at Rockhole, and two deposits were mined. The uranium was mainly present as pitchblende, located mainly in veins and fractures, with some pitchblende nodules in places reaching up to 25 cm in diameter. There were also some gold found along with the pitchblende, as well as lead up to 5% in concentration. A dispersion halo, where uranium minerals are dissolved from the primary ore and transported through surrounding rocks, was evident from El Sherana to El Sherana West, although the uranium mineralisation was patchy.
Scinto/Koolpin Creek - This was a small area of three minor deposits, Scinto 5, Scinto 6 and Koolpin Creek, plus other prospects and radioactive anomalies (the most notable of which was Stockpile). They were located between the more significant deposits of El Sherana and Palette. The Koolpin Creek deposit consisted of uranium in the form of pitchblende, although the interpreted geology suggests that up to 30 m of the ore zone been eroded in a past geologic era (since the ore was at ground surface and the geologic structure suggested the main ore body to be above this point). Some pitchblende was found at Scinto 5, but only secondary uranium mineralisation was found at Scinto 6.
Palette - The uranium was found in small shears and fractures of a local sandstone, although uranium was also found in siltstones and ironstones. The uranium was found in veins and nodular pithcblende, similar to El Sherana. Some native gold was also found as veins in the pitchblende, along with minor amounts of pyrite, chaclopyrite, galena and marcasite.
Saddle Ridge - The Saddle Ridge region contained two small uranium deposits, and a number of prospects and radioactive anomalies. The deposit was developed as an open cut mine. The uranium was mainly present as torbenite, although pitchblende was also noted. The smaller deposit, Skull, was only 300 m to the south-east, and consisted of small nodules of pitchblende. A further 800 m south-east of Saddle Ridge a shaft was sunk into another radioactive anomaly (the BMR No. 1 anomaly, known as Saddle Ridge South), and although it gave interesting geological and mineralogical information, apparently no mining took place. A further prospect 800 m to the east of Saddle Ridge, aptly named Saddle Ridge East, was also found to contain minor torbenite.
Coronation Hill - The Coronation Hill deposit, developed as an open cut mine, contained uranium mineralisation within a 20 m diameter volcanic pipe. The uranium was mainly pitchblende, often associated with gold (which often formed separate ore zones).
Sleisbeck - The Sleibeck deposit is located 30 km south-east of Coronation Hill. It mainly contains uranium as pitchblende, although secondary mineralisation was also present with phosphate and minor copper, nickel, cobalt and arsenic.
- "Warning" sign photo taken near the (former) Rockhole tailings site in July 1999.
- All unmarked photos from July 1999, unless specified.
1 - Mining In Kakadu : The Case For Co-Existence, Australian Mining Industry Council (AMIC) Education Brochure, 1991 (? - no date given).
2 - R F Cull, K Duggan, T J East, R Marten & A S Murray, 1986, Tailings Transport and Deposition Downstream of the Northern Hercules (Moline) Mine in the Catchment of the Mary River, NT. Proceedings of the "North Australian Mine Rehabilitation Workshop No. 10 - Environmental Planning and Management for Mining and Energy", Darwin, June 7-12, 1986. Edited by P J R Broese van Groenou & J R Burton.
3 - I H Crick, M D Muir, R S Needham & M J Roarty, 1979, The Geology and Mineralisation of the South Alligator Valley Uranium Field, Proceedings of the "Uranium in the Pine Creek Geosyncline", Sydney, June 4-8, 1979. Editded by J Ferguson & A B Goleby. Published by the International Atomic Energy Agency (IAEA), Vienna, 1980.
4 - R S Needham & M J Roarty, 1979, An Overview of Metallic Mineralisation in the Pine Creek Geosyncline, Proceedings of the "Uranium in the Pine Creek Geosyncline", Sydney, June 4-8, 1979. Editded by J Ferguson & A B Goleby. Published by the International Atomic Energy Agency (IAEA), Vienna, 1980.
5 - R Annabell, 1977, The Uranium Hunters, Published by Rigby Limited.
6 - Office of the Supervising Scientist, Uranium Mining in the Northern Territory, Fact Sheet (January 1996).
7 - Office of the Supervising Scientist Annual Report 1993-94.
8 - The Gulliver File - BHP Dossier.
9 - Waggitt, P W, 1998a, Hazard Reduction Works at Abandoned Uranium Mines in the Upper South Alligator Valley, Northern Territory. In: Radiological Aspects of the Rehabilitation of Contaminated Sites. R. A. Akber, and P. Martin, (Ed's). Office of the Supervising Scientist, Darwin.
10 - Uranium Research Group, 1998, A Case for the Inclusion of Kakadu National Park in the List of World Heritage Properties IN DANGER. A Submission by the Uranium Research Group to the World Heritage Committee. October 22, 1998. 101 pages.
11 - C E Prichard, 1965, Uranium Ore Deposits of the South Alligator River. In : Geology of Australian Ore Deposits. 8th Commonwealth Mining and Metallurgical Congress, Australia and New Zealand, 1965. Ed. J McAndrew, Australasian Institute of Mining and Metallurgy (AusIMM), pages 207-209.
12 - G M Mudd, 1999, Compilation of Uranium Production History and Uranium Deposit Data Across Australia, March 1999. Unpublished Report for the Anti-Uranium Collective of Friends of the Earth (Fitzroy).
13 - M F Foy, 1975, South Alligator Valley Uranium Deposits. In : Economic Geology of Australia and Papua New Guinea - Vol. 1 Metals, Ed. C L Knight, Australasian Institute of Mining and Metallurgy (AusIMM), pages 301-303.
14 - Construction Group, 1988, Rehabilitation Proposals for Abandoned Uranium Mines in the Northern Territory. Commonwealth Department of Administrative Services, Report 88/2, April 1988, 114 p.
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