ENVI RONMENTAL CASE STUDIES @ souTH PACTFTC REGTONAT ENVTRONMENT PROGRAMME (SPREP) South Lrj sourH PACrFrc coMMlssloN (sFc), NoUMEA NEW CAITDON|A produced with financhl assistance fiorn the 3t".$,.5 @) UNITED NAT|oNS ENVTRONMENT PROGRAMME (UNEP)

THE EFFECTS OF MINING ON THE ENVIRONMENT OF HIGH 'ISLANDS: A CASE STUDY OF GOLD MINING ON MISIMA IS- LAND, PAPUA Nf,W GUINEA

BACKGROUND

Papua is currently un- dergoing a minerals exploration boom, especially for gold, and more than l0 potentially economic deposits have already been located. The geological and environmental settings in which these gold deposits have been found are very like those in other Pacific countrieso especially the Solomon Islands, Vanuatu and Fiji, and it is certain that these countries will eventually face dif- MirimE. The rite of the open mine pit. ficult planning and decision-making The dirturbance har been caured by drilling to situations similar to those currently determins the cxtent of the ore body. being experienced in . Like all other mineral development projects, those in Papua New Guinea have associated problems. There has been considerable publicity for in- stance surrounding environmental management problems such as those of the Ok Tedi and Bougainville mining projects (Chambers 1985), and more recently over a proposed gold mine at Porgera. The even more severe impact of nickel mining on the environment of New Caledonia has been described by Dupon (1986) in the first of the SPREP Environ- mental Case Studies series. As the pace of mineral development in- creases so will the degroe and extent of environmental impact. The brunt Papua New Guinea is unique in the that the proponent of a new of such impact will continue to be Facific region in that its Constitution development project liaises with the felt most keenly by the local corn- has specifically recognised the Department of Environment and munities whose land witl be nationrs responsibility to ensure that Planning and if necessary prepares alienated and whose traditional its environment is protected and its an Environment Plan. The Plan, resources will be destroyed or natural resources are wisely used. along with the economic and techni- degraded while the benefits are This responsibility is given legisla- cal feasibility studies, provides the spread more widely throughout the tive effect through the Environment basis on which g,overnment approval country. Planning Act, 1978 which requires for the project is judged. In this case study the environmental planning and management strategy proposed in the Environmental Plan for the gold mining project (Natural Systems Research Pty. Ltd. INSRI 1987) is described and analysed. A major feature of this strategy is that it will be the first in Papua New Guinea to utilise marine disposal of soft rock waste and of tailing (residue) produced by the treatment of the ore. This form of disposal has already been proposed for two other high island gold mines in Papua New Guinea, on Lihir and Fergusson Islands, and is likely to be widely implemented on high islands throughout the Pacific region.

The eite of the open mine pit viewed from the west. The ore body liea beneath the prominent hill which hae been dieturbed by exploration activitiee. When mining haa been completed after l0 years the hill will have been completely removed and replaced by a deep pit. THE MISIMA GOLD MINING PROJECT

Government approval for Placer s'yflf\gi"' (PNG) Pty. Ltd. to proceed with this A -'' project was granted in late | 987, ISLAND A construction work began almost im- Nor r on gs mediately afterwards and it is ex------E r o u s -\*J a/- * o q o o, o pected that the first gold will be ex- Kilomelres tracted in early 1989.

The objective of the project is to develop and operate an open cut mine and process facilities to recover gold and silver, supported by the I necessary infrastructure (NSR 1987). c The total ore to be extracted is 56 ) million tonnes (Mt) at a stripPing ratio of 1.3 tonnes of waste to each tonne of ore. This would allow the mine to operate for a little more than l0 years at the planned produc- tion rate of 5.475 Mt/annum. Mining ./ -. OPEN will be by conventional open pit PIT., techniques and three categories of MINE material will be removed from the pit: ore (56 Mt), hard rock waste (35 Mt) and soft waste (35 Mt). HARD ROCK WASTE DUMPS The ore will be delivered by trucks to the processing plant located on / o*r' the coast. The hard rock waste will be delivered to dumps close to the 1o.r (/srocKPrLE open pit. The soft waste comprises CONSTRUCTION \" incompetent oxidised rock which \ CAMP to will not store safely in stable dumps; (; Bwogooio Airporl instead it will be hauled to the south )* Norl on coast and dumped directly into the --*"""{Ilftt" ocean adjacent to the plant site. PLANT\w SITE SOFT WASTE The ore treatment plant will be a TAILING PIPELINE ACCOMMODATION CENTRE conventional gold cyanidation plant with gold recovery by the carbon- in-pulp process. The ore will be ground in a ball mill to a diameter of 125-235 micromillimetres. The tailing left after the gold and silver have been extracted will consist of a mixture of water, mud and chemi- cals such as cyanide used in the ex- traction process. This tailing will flow to a mixing tank where it will be diluted with sea water to reduce the residual cyanide concentration to a level acceptable for deep ocean discharge down a pipeline.

The mining, processing and waste disposal strategy summarised above was decided on after more than eight years of environmental, Newly prepared yam gardeng in forest clearing. economic and technical feasibility eastern end Misima Island which studies, The grade of the Misima of soon from December to March. Al- is 40 km long and l0 km wide at its deposit is extremely low at about 1.3 though the annual rainfall is over broadest point. western grams of gold per tonne of ore. This The end is 3,000 mm and is relatively regular rugged and rises maximum is because in the course of past min- to a al- throughout the year, droughts are titude 1,035 metres sea ing activities most of the high grade of above known to occur, especially during level. The eastern end is less rugged ore was extracted by underground the south-east trades season, and this and at its highest point, in the cause mining methods. In adopting this can food shortages or even vicinity of the mine site, rises to 413 famines. strategy the developer ensured the metres. Most the eastern half economic viability of an otherwise of of the island consists of low grade The island currently has adequate marginal project while at the same metamorphic rocks with porphyritic land to support its population of time reducing to a minimum the intrusions. The relatively flat-lying about 9,000 people which is con- area of otherwise productive agricul- centrated along coastal coastal strip is largely formed on the strip. It tural land required. On the negative retains which raised coral limestone terraces. ample areas of forest side, the dumping of soft waste will are rich in a range of raw materials adversely affect the nearshore en- and bush foods, and the surrounding The hilly interior at the eastern end vironment, and the resources avail- sea resources. is covered in lowland hill rainforest is rich in marine able from it, for a distance of up to Commercial and small-holder copra which shows evidence of having 9 km along the coast. and cocoa production utilises almost been disturbed within the last 50 years all of the flat coastal land, and sub- The mine is expected to produce by cyclonic activity, timber- getting for mining gardening. sistence production from shifting about 77.2 md 1,175 tonnes of gold and by The coastal strip and foothills have cultivation is largely confined to the and silver respectively. The total been cleared in the course shift- foothills and mountainous interior. production would amount to export of ing cultivation and the original rain- earnings of about US$ 935 million at practise forest has been replaced by wood- Misima islanders a form of gold and silver prices of US$ 385 shifting cultivation characterised by and US$ 6 an ounce respectively. land, characterised by the prominent, fast growing tree mixed gardens usually dominated by single yams Kleinhovia hospita. a staple, in this case (Dioscorea spp.). ENVIRONMENTAL AND SOCIAL SETTING Two seasons occur on Misima: the south-east trades to from April THE November and the north-west HIsroRY oF I\IINING The Misima gold deposit lies at the mon- Alluvial gold was discovered on OPEN PIT MINE Misima Island in 1888 and about 100,000 ounces was produced from alluvial workings before the source of the gold was traced to the head- waters of Cooktown Creek in 1904. Mining of the underground lode (vein) gold began in l9l5 and con- HARD ROCK WASTE SOFT ROCK WASTE 55 Mf 35 Mr tinued at the rate of around 100 tons a day until early 1942 when the ap- proaching Japanese forces caused the o/o 6O stored rn [+oz" o".rnr"J-l ,n ,th"*"] evacuation island. Attempts sf oble dumps In open prt [o*o"o of the I ] after the war to re-commence min- ing were unsuccessful, largely be- cause of extensive collapse in the h*- underground workings. The total output from alluvial and Rapid recovery of the coral reef is (NSR 1987, section l0) and this has Hughes, P.J. & Sullivan, M.E. (t98S) expected once mining stops, as was been agreed to, with modifications, Population, Iand use and mining in the case along the coast adjacent to by the Department of Environment Papua New Guinea, Yagl-AmDz. The Cooktown Creek after mining ceased and Conservation and Placer (PNG) University of Papua New Guinea in 1942. Recovery, or restoration, of Pty. Ltd. Journal of Social Sciences & the reefs is brought about naturally by REFERENCES: Humanities | 5(D:a0 -62. recolonisation and regeneration. (1985) Chambers, M.R. Environmen- Natural Systems Research Pty. Ltd. tal management problems in Papua (f Tailine disoosal 987) Misima Project Environmental New Guinea. The Environmental Plan. Placer (PNG) Pty. Ltd., Port Professional 7: I 78-85. plant Moresby (3 volumes). The location of the treatment Dupon, J.F. (1986). The effects of on the coast, the avaibility of deep mining on the environment of high Placer Pacific (1988) Annual water short distance from the Ltd. a islands: a case study of nickel mining Report 1987. Placer Pacific Ltd., shore and the absence of any deep in New Caledonia. Environmental Sydney. water subsistence or commercial Studies: South Pacific Study I. provided Case fisheries resources use, an South Pacific Regional Environment This document's contents, conclu- opportunity for the disposal of tail- Programme, Noumea, New sions and recommendations do not ocean. The proposed ing deep in the Caledonia. necessarily ref lect the views of tailing disposal system submarine P.J. Sullivan, M. (1987) UNEP or SPC. The designations pipeline transporting Hughes, & consists of a gardening? Potential employed and the presentation of the tailing from the plant, a mixing Goldmining or land use conflict on Misima Island, material do not imply the expression tank, an outfall discharge a PiPe, Papua New Guinea. In A. Conacher of any opinion whatsoever on the seawater intake pipe and f low (ed) Readings in Australian Geog- part of UNEP or SPC concerning the regulating devices (NSR 1987: 27 - raphy. Institute of Australian Geog- legal status of any state, territory, 30). The tailing will be mixed with raphers (WA Branch) & DePartment city or area or of its authorities, or seawater in the mixing tank and the of Geography, University of Western concerning the delimitation of its resulting slurry will be discharged , Perth. frontiers or boundaries. through the outfall pipe to the ocean at a depth of between 75 and 100 i"lir* *i, metres. The slurry will be denser *'*.:i, than the surrounding ocean water at the discharge point and it will flow down the steep submarine sloPe as a density current and will not mix with, or pollute, the surface seawater.

The tailings will accumulate on the deep sea floor and smother marine habitats there, either forcing away or killing those animals which cannot adjust to the new conditions. The Misima people do not fish at such great depths and there is little potential for commercial deep water fishing. Derelict etamp battety ured to crurh the gold-bearing ore during the underground phase of mining.

ENVIRONMENTAL MONITORING OCopyright South Pacific Commission' Leaflets available in this series are: Leaflel 5 - fhe ellects ol mining ott -fhe high is- AND MANAGEMENT l 989. Leaflet | - ellacts ol mintng on the envinnmtn! ol The South Pacific Commission the environmcnl ol high rs' lands; A case study- ol gold authorises the reproduction of this lands: ,4 case study ol nickel ntining on Misima lsland. These assessments of the likely im- material, whole or in Part, in anY nining iil New Caledonn Popua New Curnea pacts project on the environ- form. provided appropriate acknow- Leaffet 2 - llallis and Futwra: Msu of the ledgement is given. agaiilsl the loresl Copies of leaflels in this series can ment are predictions, not established Original lext: English. L.eaflet -l - Atolls and lhe cl'clotrc be obtained from: ha:srd; A case sludl' ol the SOUTH PACIFIC RECIONAL facts. It is therefore important that Tuamotu Islands ENVTRONMENT PROGR At\IITIE impacts are carefully and South Pacific Commission Leaffet 4 - Paciltc phosphote island SOUTH PACIFIC COMMISSION the actual Cataloguing- in-publication dala tnrtronmeilIs vcrsus the miil' B.P. D5. Noumee Cedex regularly monitored by the govern- ing industrt: Atr wtequal New Caledonir Philip J. ment, the company and the Misima Hughes, slruggl? community to ensure that they do The effects of mining on the en- vironment of hiSh islands : a case not exceed the levels Predicted in study of gold mining on Misima the Environmental Plan, and that lsland, Papua New Guinea. (Environmental case studies : Preoared bv Philip J. Hushes those impacts which do occur are South Pacific study : 5) Univirsity New Guinea managed appropriately so as to mini- "tlltnt: | . Cold mines and mining- - South Pacific Resional Environment Programme mise their adverse effects. Environmental aspecls-Misima ls- Souih Pacifrc eomfirission, Noumeq, Nevy Caledonia, land (Papua New Guinea) L Title with financial assistance from the A detailed environmental manage- ll. Series United Nations Environment Programme was ment and monitoring Programme 1i3.850995 AACR: Printed bv Stredder Print Limited, proposed in the Environmental Plan rsEN 9E:-?03-050-9 Aucklafid, New Zealand, 1989 popula- underground workings since 1888 is in its lower reaches. The coral reefs one major issue. Most of the estimated to have been aP- near the mouth of Cooktown Creek tion of about 9,000 people lives proximately 250,000 ounces. The must have suffered considerable along the coast of the eastern end of early mining activity supported its damage from the continuous dis- the island, and although there is cur- own infrastructure and a con- charge of mine wastes from Cook- rently no shortage of gardening land siderable number of expatriates and town Creek but they have now fullY the population is increasing rapidly local people were employed by the recovered. and there was concern that alienation of land for the mining project might mining companies. PREDICTED ENVIRONMEN- THE lead to land shortages. TAL IMPACTS OF THE OPEN The environment legacy of intermit- CUT MINE tent gold mining over the past 100 Population-land use studies demonstrated that even if the mine years is evident today in the form of The major issues raised in the En- did not proceed, by about the year old tunnels, roadworks, derelict vironmental Plan by the development 2010 land shortages would begin to buildings and equipment and the this open cut gold mine and its of seriously the local people. degraded vegetation surrounding the infrastructure were as follows (NSR affect Thus it was realised from an early old workings. In Cooktown Creek | 987:48): and its tributaries there was a con- stage in project planning that it was highly desirable that wherever pos- siderable build-up of waste rock and (a) the capacity of the island to sible, project infrastructure should mercury amalgamation and cyanide physically accommodate the be placed on land of low produc- tailing which were dumped into the project and continue to provide gardening land and stream system without any pre- gardening tivity for use as sufficient land for a bushland treatment. Most of this has since growing population; for exploitation of been transported out to sea but some resources. The mine site and hard of it has accumulated in the lower (b) the capacity of the streams and rock waste dumps will be in hilly Cooktown Creek valley. surrounding ocean to assimilate terrain on largely non-productive wastes from the project; land away from populated and gar- This long-term but relatively small- dened land. The processing plant and scale phase of mining must have had (c) the effects of the project's land accommodation facilities will be lo- presently a considerable impact on the ter- requirements and discharges on cated on freehold land restrial, riverine and nearshore natural ecological values, and used as plantations. Only the marine environments. The hills sur- the subsistence and commercial haul road and the low grade ore rounding the mine site are well resources utilised by local stockpile will be situated on produc- vegetated but the original forest people. tive village-owned land. Money cover has only partially returned reaching the local community from more than 40 years after mining Land and Resource Use Impacls mining will allow increased pur- ceased. The Cooktown Creek system chases of food from stores and this has fully recovered and sago stands Land alienation and the associated may offset some of the effects of have long since been re-established depletion of traditional resources was pressure on subsistence land. pipeline; and hauling the soft waste to the ocean for surface discharge (NSR 1987: 32-33). The ocean sur- face disposal method was chosen be- cause it was considerably cheaper than the other options. A soft waste dump site will be constructed along the shoreline below the plant site. When soft waste is dumped from t09 tonne rear-dump trucks over the dump face the material will cascade down the steep slope as a density current like that produced by the submarine tailings disposal system. The submarine slope would become covered by a veneer of soft waste Sediment washing out from Cooktown Creek as a result of mining exploration activities. sediment and a localised increase in The dumping ofsoft wastea into the sea will create a permanent, and even larger, turbidity would occur at and sur- plume of turbid (dirty) water than thie. rounding the dump site. Soft waste production will peak at 7.3 Mt a Stream Impacts would need to be sited in the moun- year, and this corresponds to about tainous interior of the island. 20,000 tonnes a day or 183 truck During the construction phase, Preliminary investigations indicated Ioads a day. which will last about l5 months, that several dams would be needed 200,000 cubic metres sedi- about of and that there was a definite risk It was this aspect of the overall ment (mostly soil) will find its way that dams in such terrain might fail waste disposal strategy that caused further into Cooktown Creek. A due to seismic or climatic events. the greatest concern and considerable 170,000 cubic metres will reach the effort was given to predicting its Creek during the l0 year life the of Hard rock waste disposal physical and biological effects (NSR mine. Much smaller amounts will 1987: 107-126). In a zone 0.5 km reach surrounding the other streams About 60% of the 35 Mt of hard either side of the dump site the ef- project area but the impact on these rock waste will be stored in stable fects were predicted to be severe streams will be negligible compared dumps in the hilly interior on land with sedimentation damage to the with that on Cooktown Creek. Al- which is largely unproductive. The fringing coral reef and with the though most this sediment will of remaining 40% of hard rock waste water in the nearshore zone being washed sea, eventually be out to will be used to back-fill one end of frequently turbid. This would lead to there will be localised accumulations the open pit. Because the rocks are a marked reduction in coral fauna sediment the valleys which, in of in non-acid producing the leachate diversity and reduced numbers and the case Cooktown Creek, will af- of from these dumps is not expected to diversity of fish. There would be a important sago swamp. fect a locally be acidic or to contain high con- significant reduction in the numbers waters will be ln addition the stream centrations of dissolved metals or of fish that could be caught by local their continuously muddy because of other contaminants (NSR l9E7:31). villagers. high sediment load. The effects would be progressively The loss sago resources is ex- of Soft waste rock disoosal less severe either side of this central pected be small and compensation to zone and would cease about 3 km to paid these losses. The will be for Three alternatives for disposing of the west and 6 km to the east of the company has already installed piped the 35 Mt of soft waste were con- dump site. Compensation will be villages water supply systems for all sidered: containment by a dam lo- paid by the company to the villagers adjacent to the project area. None of cated about I km upstream from the for losses of marine resources and these water sources will be affected Cooktown Creek mouth; milling the amenity as a direct result of dis- project by construction or operation. soft waste and disposing it, along colouration of nearshore waters from with the tailing, down the submarine soft waste disposal. Waste Disposal Seowoler -loilrng mrxing lonk

Waste disposal was the other main issue. Two alternative tailing disposal techniques were considered; land disposal and ocean disposal (NSR 1987: 26-30). Land disposal would have required the construction of a dam capable of permanently storing the tailing and soft waste rock and withstanding extreme rainfall and run-off during cyclones. As all the flat coastal land is currently in productive use, the tailing dam