Number 2 July 2003

Reducing Historical Pollution The Savage River Rehabilitation Project (SRRP) has

made steady progress since the last savage riverrevival newsletter (February 2001). We now have a

better understanding of the acid rock drainageproblems at the mine site. This has enabled us toimprove its environmental performance, and theproject is well placed to achieve its aims.

The Savage River mine is located in northwest Tasmaniain steep, mountainous terrain surrounded by areas ofhigh wilderness value, including the Savage RiverNational Park. The Savage River flows through the minesite and eventually discharges into the Pieman River, atrophy trout fishery. The climate is cool and wet, with ahigh average annual rainfall of approximately 1900 mm.

Operations during the first 30 years of the original open cutiron ore mine, established in 1967, have causedenvironmental harm to the entire Savage River and itstributaries. The principal cause of degradation is acid rockdrainage seeping out from 200 million tonnes of waste rockdumps around the site. Sediment from the old mine hasalso contributed to the water pollution and streamdegradation.

The 30 km stretch of the Savage River below the mine isdirectly affected by historical water pollution. In 1995, thisriver stretch was found to have lost 90% of itsinvertebrate diversity and 99% of its invertebrateabundance. Fish life there is also greatly reduced.

The Savage River above the mine is also affected becausethe pollution prevents fish from migrating between theriver and the sea, which is an essential part of the lifecycle of most Tasmanian native fish. Surveys show thatthe native fish fauna is severely depleted in the SavageRiver National Park, which is situated above the mine.

Several remediation works by the new miningcompany have significantly reduced the waterpollution. The alkali flow-through structure inBroderick Creek has increased alkalinity and calciumlevels downstream of the mine, thus reducing metaltoxicity. The use of previously unused pits for bothstormwater and acid rock drainage treatment haslowered levels of metals in the Savage River.

We expect that further improvements over thenext five years will lead to the Savage Riversupporting a modified healthy ecosystemdownstream of the mine. This in turn will allowgreater fish migration into the National Parkabove the mine.

Toxicity targets achievedToxicological studies have been conducted since 2000 toinvestigate the key parameters responsible for biologicaldegradation downstream of the Savage River Mine (asreported in the previous newsletter). The studies foundthat copper concentrations in the Savage River wereoften at toxic levels and should be reduced,especially when calcium/alkalinity levels are low.As a result, the SRRP set environmental targetlevels based on this research.

The threshold line in the graphs belowrepresents the first stage targets, whichare mainly based on the toxicity ofcopper to fish. Values above theline represent waters that arelikely to be more toxic to fish.

Savage River Mine as seen from the air

The Newsletter of the Savage River Rehabilitation Project

Managing current waste dumping

ABM is striving to make its waste dumping cost-efficient. All wastes are classified into one of thefollowing four waste categories:

A-type alkaline-rich rocks, such as magnesite and calcite chlorite schist

B-type neutral or rocks of low acid-producing potential

C-type extremely weathered rock, i.e. clay

D-type potentially acid-producing rock

The D-type waste materials must be placedwithin oxidation-inhibiting waste dumps. The Aand C-type wastes are used as constructionmaterials for these dumps, and for otherenvironmental rehabilitation purposes. Both theA-type alkaline rocks and especially the C-typeclays are limited in quantity and need to be usedsparingly. The B-type wastes do not require anyspecific handling.

Designing oxidation-inhibitingdumps

The construction of oxidation-inhibiting dumpsfor D-type waste rock requires a significantamount of management, planning and miningresource allocations (including surveying, dozingand compaction), which all add up to highermining costs. In the current South Depositoperations only 12% of all waste rock is D-type.It is therefore imperative that this waste type isproperly identified and segregated to minimisewaste dumping costs.

ABM’s initial oxidation-inhibiting dump designswere designed with a highly compacted cap oflow-permeability clay. The dumps were designedwith very low-angled side slopes for long-termstability. The South West Dump (see photo) wasa trial, with the clay cap constructed around B-type material. A loose soil cover for vegetationwas not applied over the clay cap. However,revegetation trials on compacted clay slopes areunderway.

2 Savage River Rehabilitation Project Newsletter 2 July 2003

1998–2000 water quality data

The above graph shows the levels of total calcium versusdissolved copper for water samples collected from 1998-–2000. The two sample sites are:

• the ‘Savage River below South West rock dump’ situateddirectly below the mine workings

• the ‘Savage River below lease site’, which receives all otherpollution from the mine lease site.

The graph shows that 20% of water samples exceeded thetoxicity threshold for fish.

2001–2002 water quality data

The above graph shows the levels of total calcium versusdissolved copper in water samples collected in 2001 and 2002.The graph shows a significant improvement in copper levels atboth sites with no samples above the toxicity threshold.

Given that all other environmental targets, such as dissolvedaluminium and sulphate, are within the limits set by thetoxicological studies, the data represents a significantimprovement in the management of pollution sources from themine lease. The SRRP aims for further improvements becausethe current threshold has a low safety factor. The moresensitive macro-invertebrate species, such as Ceriodaphnia, stillshow a toxic response within the first stage targets.

Techniques for reducing ARD fromwaste dumps By Bruce Hutchison, Senior Geotechnical Engineer, ABM

ABM’s waste management strategies are focused onprotecting the environment from existing andpotential acid rock drainage (ARD) from both currentand historical waste dumps.

ABM South West Dump

Due to the steep topography and high rainfall atthe mine site there are several drawbacks to thisdesign, the three most important being:

• the high cost

• the limited quantity of material that can beplaced on the steep hillsides

• and that rainforest tree roots will eventuallybreak through the clay liner.

During a site workshop with ABM supervisorystaff, one of Environmental GeochemistryInternational Pty Ltd’s consultants pointed outthat less permeable clays can provide anadequate oxygen barrier if the clay remainssaturated. A more cost-efficient method of claycapping was devised that takes advantage of thehigh rainfall of the West Coast. In this design (seediagram below), saturated clays are simply enddumped off the D-type waste tip head to form alayer that is 5–10 metres thick. Coarse A-typearmouring is then end dumped over the clay toprovide stability and also a thermal blanket. Thisrock armour inhibits drying of the clays due to itsthickness of 10–30 metres (depending on theheight of the dump). Any drying that may occurin the summer months will be quicklyreplenished during the other three ‘wet’ seasons.

Cleaning up historical dumps

ABM is also committed to the rehabilitation ofthe historical dumps that are emitting substantialquantities of ARD.

B Dump is a good example of a large historicaldump that is being rehabilitated by ABM inconjunction with the SRRP. Studies conductedby the SRRP indicate that approximately 40% ofthe ARD from the mine site (based on copperload) flows down Main Creek, which receivesmost of the drainage from B Dump and thetailings dams. SRRP rehabilitation proposals callfor collecting the ARD in Main Creek andtransferring it to a treatment plant, before it isdischarged into the South Lens Pit.

To reduce the amount of water requiringtreatment, ABM will:

• permanently divert tailings dam runoff intoTownsend Creek, away from the upperportion of Main Creek

• construct a water-shedding cover over thetop of the original dump surface

• construct alkaline wrap-around dumps on theeastern and northern side slopes.

Studies have indicated that these combinedmeasures could reduce the amount of ARD beingcollected to around 10–20% of the previous flowsin Main Creek.

Water-shedding covers

ABM has had to adapt its water-shedding cover design tosuit the available materials and construction techniques. Thecompany’s initial design had a low-permeability clay layersitting at a 2% gradient. However, trials indicated that muchof the ‘clays’ were in fact ‘silts’ and that the required low levelof permeability (10-8 to 10-9 m/sec) could not be achieved, nomatter what devices were used to compact the clays. Tocompensate for the higher permeability of the clay, the gradientof the water-shedding cover has been increased to 3%–5%, sothat the water runs off quickly before it can penetrate the cover.

ABM also found that where waste rock (A and B types) wereplaced over the clay for haul truck roadways, the 150 tonnepayload trucks had broken down the rock and compacted it tothe required 10-8 m/sec permeability level. Loaded haul trucksare now directed around the dump so that they break downand compact the A and B-type rock waste in the roads.

Alkaline covers

Waste dump management techniques have recently begunfocusing on the use of ‘alkaline’ covers to increase the alkalinity ofrainwater as it seeps into and off dumps. When alkaline watersreach the pyrite-bearing rocks, micro-encapsulation is thought tooccur as a result of acid-base reactions. This retards the leachingof polluting minerals.

In some cases the use of certain alkaline materials, such aslimestone, has caused the formation of mineral coatings that‘clogged’ up the pathways for water transport within the wastedumps, thereby creating a ‘seal’ to the dump.

The eastern side of B Dump was too steep and high to form aneffective oxygen- inhibiting cover, so ABM has expanded theupper B Dump surface by creating wrap-around levels of calcitechlorite schist (A-type material) on the eastern Main Creek side ofthe dump (see the photo below). The company hopes that thiswill eventually form an ‘alkaline’ water-shedding cover, althoughrainwater will still seep directly into the side batters andeventually down to the base of the dump. Monitoring over thepast few years has shown that Broderick Creek becomessubstantially more alkaline as its waters pass through the calcitechlorite schist of the coarse rock flow-through structure. This isa goodindication thatthe wrap-around A-typematerial may bean effectivealkaline water-sheddingcover.

Savage River Rehabilitation Project Newsletter 2 July 2003 3

Constructing wrap-around ‘alkaline’

levels on B Dump

ABM’s revised oxygen-inhibiting dump design

A 1 m wide, concrete-lined trench was builtalong the left bank of the river to collect the aciddrainage. The 150 m long trench delivers theARD into the pump works – a buried plastic tankinto which a stainless steel pump can belowered or raised. The pump delivers the ARDinto South Lens Pit, via a 100 mm diameter poly-pipe, at a rate of up to 15 l/s. A bridgeconstructed from an old PMI drill mast providesaccess to the pump station and support for thepoly-pipe.

A large rock bund protects the trench from rivererosion. To prevent rocks and sediment fromfilling the tank and fouling the pump intake,ABM installed grates and a flap lid thatautomatically closes during flood conditions.

Savage River RehabilitationProjects

Whole of site feasability study

By David Brett, Thompson & Brett, Consulting Engineers

Over the past few years DPIWE has carried out anumber of studies into the sources of pollutionfrom the historical mine works at Savage Riverand reviewed options for remediation in variousareas. All of this background work has now beenapplied to a feasibility study for the whole site.The feasibility study recognises the synergiesbetween strategies to reduce contamination andappropriate treatment systems for different areas.

The SRRP Strategic Plan of December 2001estimated that to achieve initial toxicity targets,65% of total copper emissions from the site mustbe removed. Monitoring studies have shown thatthis level can be achieved by treatment of the:

• Main Creek below B Dump

• North Dump Drain

• Crusher Gully

• Old Tailings Dam.

4 Savage River Rehabilitation Project Newsletter 2 July 2003

Crusher Gully ARDTreatment Scheme

By Bruce Hutchison

As part of the Savage River RehabilitationProject, ABM (Australian Bulk Minerals) has

recently constructed a collection and pumpingscheme that removes acid rock drainage (ARD)

from seeps at the base of Crusher Gully andtransports the polluted water to the alkaline waters

of South Lens Pit for treatment.

The ARD originates from historical dumps left by theformer mine owners, Pickands Mather & Co. Inc. (PMI).The dumps are underneath the BC1 conveyor and themain access road down to the river.

For years, ARD has been seeping directly into theSavage River. These seeps are normally exposed alongthe riverbank, except when it is inundated by floodwatersduring high flow conditions. The highly compacted nature ofthese dumps means that seepage is slow but constant, leadingto increased water pollution during the lower summer flows,when receiving volumes are lower.

Collection trench and pump works

Pump works and access bridge

Crusher Gully treatment scheme in flood

The feasibility study focussed on passive systemswhere possible but inevitably a treatment systemwill be required.

The feasibility of the rehabilitation project isaffected by the rugged topography at SavageRiver and the high annual rainfall, ranging from1500 mm per annum to over 2800 mm perannum. The high stormwater runoff, which isbetween 75% and over 90% of rainfall, results inhigh flows to be handled by drainage collectionsystems. Consequently, a major factor indeveloping an economic strategy forrehabilitation is to maximise the diversion ofclean water from sources of contamination.

Monitoring of Main Creek above Townsend Creekduring the period when the tailings dam outflowwas diverted into Townsend Creek clearly showedthe significant impact of B Dump on stream flowrates in the local catchment. This diversioneffectively removed the tailings dam overflow fromthe section of Main Creek downstream from thetailings dam and upstream of Townsend Creek.This left only the local catchment flow in MainCreek, with B Dump occupying a majorproportion of the catchment. The residual flow inthe creek was surprisingly constant andrepresented approximately 70% of incident rainfall.The flow pattern mirrored the 60-day movingaverage of rainfall, indicating that most of therainwater was percolating through the dumpsand disturbed ground and emerging ascontaminated seepage over a period of months.This phenomenon correlated well with the resultsof SoilCover modelling of the waste dumps. It

demonstrates that flows in Main Creek could besignificantly reduced by capping and diversion ofrunoff from disturbed areas, which is being done byABM as part of their current mining operation.

Reduction in flows, however, does not necessarilyreduce the levels of contamination and so treatmentsystems were reviewed. These included the optionsshown in the table below:

Preliminary designs were produced for a variety ofoptions to develop cost estimates to ± 30%. Theseestimates considered the operating and maintenance costsover a 60-year period and Net Present Value (NPV)estimates were assessed for each option. This allowed adirect comparison so options could be ranked by their long-term economic viability.

The study concluded that, in general, passive systems wereun-economic. However, trials of a alkaline system developedby Earth Systems were recommended, together with anongoing review of high infiltration systems.

Active treatment in conjunction with clean flow diversion wasidentified as the priority, because it is the most cost-effectivemethod. A key factor to the feasibility of active treatment wasABM’s central pit management which will make at least one ofthe open cut pits available for sludge disposal. This is particularlysignificant due to the very large volumes of treated ARD sludgesfrom simple treatment processes. The Earth Systems’ autogenousmill process using magnesite proved to be the most economicaloption if the treatment efficiency could be maintained at around60% by cleaning the sludge particles after treatment by contactwith the turbulent discharge water in site drains and, ultimately,in the pit. Field trials are proposed to confirm this. If theautogenous mill process proves to be not sufficiently efficient,then more conventional lime treatment will be required.

Savage River Rehabilitation Program Newsletter 2 July 2003 5Savage River Rehabilitation Project Newsletter 2 July 2003 5

Passive Treatment Systems

Water covers Some scope to at least partly flood tailings at Old Tailings Dam.

High infiltration alkali covers An emerging technology to introduce alkalinity to the top of dumps thatavoids the problem of passivation by coating alkali sources with precipitate.Potentially very expensive if not implemented as part of the mining operation.

Oxygen barriers The site climate helps to keep soil covers saturated but oxidation of sitedumps is already advanced and dumps are likely to discharge contaminatedseepage for decades even if further oxidation is stopped.

Water-shedding covers In Savage River, climate covers can not eliminate seepage but can reduceflows and thus lower treatment costs.

Alkali flow-through drain The existing flow-through spillway in Broderick Creek has proved to be asignificant source of alkalinity.

Active Treatment Systems

Magnesite Available on site and possibly suitable as a reagent using an autogenous millsystem or purpose-designed PULSE reactor.

Lime Expensive and produces low-density sludge but is a proven technology.

Tailings Potential use while ABM is actively mining.

Bauxol Expensive and unproven but potential for final polishing of effluent.

Calcium carbonate schists On-site material but limited scope for increasing pH.

The overall site concept proposes:

• A centralised autogenous milltreatment plant (subject toefficiency testing) located near theABM security gate entry area,discharging treated water toCentre Pit via a series of turbulentchannels and settlement ponds.

• Collection of ‘concentrated’ ARDfrom Main Creek and Old TailingsDam sites and pumping to theautogenous mill plant. (Note thatARD will be ‘concentrated’ bydiverting as much clean water aspossible from the sources ofcontamination.)

• Diversion of North Dumpdrainage via a pipeline to amixing pond above Centre Pitwhere it will be mixed withalkaline water from theautogenous mill plant beforeentering Centre Pit.

• Diversion of the easterncatchment of North Dump Drainto the Old Tailings Dam.

The total NPV of the works itemsnoted is estimated at in the order of$13 M.

Of particular interest, in conjunctionwith the rehabilitation project, wasthe feasibility of providing a mini-hydro scheme. This would involveexcavating channels so water fromboth the Old Tailings Dam and MainCreek Dam is diverted via a penstockand power station on the SavageRiver below the South West Dump.

6 Savage River Rehabilitation Project Newsletter 2 July 2003

Overall site concept for the proposed ‘whole of site’ rehabilitation program

Prototypeautogenous mill

treatment system inaction at Port

Macquarie NSW

Positive peer review of projectThe Strategic Plan of the SRRP calls for anindependent review of the project every threeyears. The first review was commissioned in early2002 after an extensive search for internationallyrecognised experts. The SRRP ManagementCommittee was delighted to employ the highlyrespected panel led by Dr David Williams(University of Queensland), Dr Stuart Miller(Environmental Geochemistry International PtyLtd), Dr Ward Wilson (Unsaturated SoilsEngineering Ltd), John Miedecke (JohnMiedecke and Partners Pty Ltd) and Dr ChrisHumphrey (Environmental Research Institute ofthe Supervising Scientist).

The purpose of the review is to ensure that theproject is on track both strategically andscientifically and maintains a focus on BestPractice Environmental Management as itdevelops.

In March 2002, the review panel toured themine site and Port Latta and was given access toall reports commissioned by the SRRP. Thefindings of the review were comprehensive andvery informative. We now have a betterunderstanding of the ARD processes occurringwithin the old waste rock dumps. The paneldeveloped a risk assessment method fordetermining priorities now and into the futureand some recommendations were implementedalmost immediately.

In general the review panel found that theproject was progressing well. The panel agreedwith the SRRP team that solutions were possibleand suggested additional avenues to explore toachieve the project’s goals. These included:

• greater emphasis on mitigation

• investigating the use of alkali covers.

The review panel also agreed that the compactedclay covers currently used for oxygen barriers werenot practical for the waste rock dumps on the site,given the topographical constraints and the materialsavailable. Subsequently, Environmental GeochemistryInternational and ABM worked together to develop amore cost-efficient design suited to the steeptopography of the West Coast rainforest (described inthe previous article).

The peer review process was invaluable and the SRRPManagement Committee is looking forward to having itswork reviewed again in 2005. By this time, progress towardsa significant reduction in pollutant loads in the Savage Rivershould be well underway.

Environmental Rehabilitation aroundPort LattaBy Greg Taylor, North West Land Managers

In addition to environmental rehabilitation at Savage River,the SRRP has also been significantly involved in tworehabilitation projects in the area around Port Latta, the site ofthe iron ore pelletising plant currently operated by AustralianBulk Minerals (ABM).

The first project was participation in Tasmania’s largest Coastcareproject, which involved sponsorship from industry (ABM), stateagencies (DPIWE/SRRP), local government (Circular HeadCouncil) and the local community. The project transformed a 5km coastal strip around Port Latta by cleaning up industrialrefuse, controlling weeds, and revegetating degraded areas withlocal provenance plants.

The second project, funded exclusively through the SRRP,involved best practice environmental rehabilitation of two

abandoned quarries near Port Latta. North WestLand Managers, who successfully tendered toconduct this project, designed and managed aprogram involving earth works, erosion controlsystems, botanical surveys, native seedcollection, plant propagation, weed controland a comprehensive monitoring andevaluation program.

Savage River Rehabilitation Program Newsletter 2 July 2003 7Savage River Rehabilitation Project Newsletter 2 July 2003 7

Earthworks, March 1999, looking north-west towards Stanley

May 2003

opportunities. North West Land Managers hasgone on to many projects including erosioncontrol and revegetation of South West Dump atSavage River, and weed mapping, programdesign and implementation of weed controlworks for Pasminco on their Rosebery Mine lease.

The achievement of the SRRP objectives for thePort Latta region is there for all to see.

8 Savage River Rehabilitation Project Newsletter 2 July 2003

The SRRP also aims to provide employment andtraining opportunities in northwest Tasmania. This

goal has been achieved, drawing together andgrowing a significant skills base for environmental

works in the region. The on-ground managers of theCoastcare project, Jeanette Morse and Greg Taylor,

formed North West Land Managers, a business nowproviding rehabilitation skills and local employment

For further information about the Savage River Rehabilitation Project, please contact:Daniel Ray, Rehabilitation Works Co-ordinatorDaniel.Ray@dpiwe.tas.gov.auDepartment of Primary Industries, Water and Environment134 Macquarie Street, Hobart, Tasmania, 7000 Phone (03) 6233 2105

Eroded quarry, looking north-east towards Port Latta jetty andpelletizing plant, prior to commencement of works, 1999

May 2003

Recontouring, spreading of stockpiled topsoil, March 1999

May 2003