Bechtel was responsible for the Savage River Slurry Pipeline design and construction. Construction required building a 366 m suspension bridge over the nearly inaccessible Savage River. The ore was crushed at the mine site, and then transported through the pipeline as a slurry to its shipping destination at Point Latta.
The Savage River Iron Ore Deposits were discovered in 1877 but the area’s isolation and apparently poor quality magnetite meant no mining resulted. In 1958 the Department of Mines drilled a few exploratory holes and the results were encouraging. Further exploration found large deposits of iron ore, suitable for commercial development. Special legislation enabled its development by an unincorporated joint venture of ten companies, including Pickands Mather and Co International of the USA, who had an agreement to produce 45 megatonnes of iron ore pellets for the Japanese steel industry.
The ore was mined by open cut methods, and concentrated by crushing, grinding and magnetic separation near the mine at Savage River. The concentrate was then pumped in slurry form to a pellet plant near Port Latta on the northwest coast. The 85 km pipeline was the longest slurry pipeline in the southern hemisphere. The first shipment of pellets was made in 1968.
The mine comprises three principal open pits – north, central and south pits – which are oriented north-south covering a 4 km strike length and separated by unmined zones of thin or low-grade material.Article continues below…
Construction of the pipeline
Construction specifications for the pipeline were based primarily on accepted pipeline practices using API 1104. An analysis of the costs of an above-ground versus buried pipeline indicated them to be essentially equal. Although it could have been argued that an above-ground installation would appear to be less expensive than burying, it was concluded that the safety and line stability aspects were the controlling factors, and a decision was made for a buried line with minimum cover.
Burying the line provided the necessary anchorage, and provided protection from windfall trees, loggers’ equipment and the curious hunters’ rifles. Experience has since shown that hunters do take pot shots at the exposed sections of the line and bulletproof shields were later installed.
Actual construction of the line started with an aerial survey in January 1966 and centre line locating and clearing was commenced almost concurrently from the north shore working toward the mine.
Clearing for survey purposes was only as wide as required by the surveying crew and this operation was followed by the opening up a 18 m-wide right-of-way. In much of the area Eucalyptus trees as tall as 61 m further complicated a difficult job.
Access into the northern area was not too difficult, but as the line proceeded south, the gently rolling area gave way to extremely rugged, heavily forested areas with very tall trees and horizontal rain forest growth. Roads in the general vicinity were non-existent and the crew worked from mobile camps, which were moved forward as clearing progressed.
In early May 1966, about half of the surveying, clearing and grading had been completed. By September 1966 the survey was complete and construction was started for the foundations of the Savage River span. The first pipe arrived in mid-October and trenching, stringing and laying operations were commenced from the north working toward the mine.
In order to meet the 10 per cent maximum grade criteria and minimum line length, approximately 3 per cent of the line is above ground, including two major spans, and minor lengths which are supported on A frames.
The combination of the grade criteria and the extremely rugged terrain has produced what might be called the ‘crookedest pipeline in the world’.
The crossing of the Savage River Gorge is 366 m long and 137 m above the Savage River. Earthworks in this area were substantial in order to provide access at each side, and to prepare the anchorage points for the suspension and wind guard cables.
The Arthur River crossing is 64 m long and 12 m above the water. Various minor crossings are supported on A frames with a total of 317 such frames being used at 40 different locations.
A total of 85 km of pipe was installed and this activity – including clearing – was completed in 15 months. As construction proceeded a hydrostatic test was applied to sections of the line varying between 8 and 16 km in length.
The test pressure was 125 per cent of the maximum working pressure or a hoop strength of 90 per cent of yield.
Soil tests along the route had indicated acid conditions and therefore the entire length of the buried line was coated and wrapped for external corrosion protection. Above ground sections were coated.
The buried line was wire brushed, primed, covered with a 20 mm PVC wrap and a 15 pound tarred felt wrapping. Rigid inspection was carried out to ensure adequate protection since even a small break in the coating tends to concentrate the corrosive action.
In addition to the coating, cathodic protection (CP) was provided during construction by means of temporary anode beds. The permanent CP system is by an impressed voltage at each end of the line.
The pipeline is still in operation. Since 1965 Savage River Mines, a wholly-owned subsidiary of Pickands Mather International (PMI), owned and operated the mining and shipping operation but after examining a number of options, decided to cease operations on completion of its current pit mining plan, with open cut operations ceasing in April 1996 and all stockpiled ore being treated by the end of 1996.
Australian Bulk Minerals, a wholly-owned subsidiary of Ivanhoe Capital Corporation, took over the Savage River lease in March 1997. A $110 million refurbishment program was undertaken to allow the production of ore to commence in November 1997. It was then sold to Grange Resources Limited.
The operation was originally designed at 2.5 MMt/a of pellet production but after restructuring in 1990 initially operated at 1.5 MMt/a.
Production of crushed ore from the Savage River open cut in 2008–09 totalled 0.995 MMcm, with 2.174 MMt of pellets being produced at Port Latta. In June 2009, the number of people employed was approximately 600 people.
A feasibility study completed in 2006 showed that mine life could be extended to 2018, with closure of the project in 2022.