Phytostabilization for Sustainable End-Use of Arsenic-Rich Mine Tailings in the Victorian Goldfields, Australia - Environmental Contamination: Health Risks and Ecological Restoration - page 434

zone.extending.downward.from.the.surface..Minor.carbonate.contributes.to.
the.ANC,.which.is.however.dominantly.accredited.to.the.large.(>40%).con-
tent.of.chlorite.and.chloritoid.able.to.exchange.cations,.including.H + .
Tailings Management
The. active. TSF. (Tailings. Dam. No.. 2). has. been. developed. within. a.shallow.
dammed.valley.and.is.fed.by.marginal.spigots..Processed.lime.gives.the.tail-
ings.slurry.a.pH.∼10.5.at.the.time.of.deposition.and.buffers.any.immediate.
acidiication..Evidence.of.sulide.oxidation.is.limited.to.minor.iron-staining.
at. the. edges. of. the. TSF. and. rarely. in. thin. encrustations. on. dried. portions.
of. the. surface.. The. entire. surface. is. utilized. by. sequential. operation. of. the.
spigots.and.will.continue.to.be.so.throughout.mine.life,.which.is.expected.
to.be.a.minimum.of.9.years..The.initial.mine.closure.plan.called.for.the.cap-
ping.of.the.TSF.with.a.minimum.of.10.cm.of.impermeable.material.(clay).and.
a. further. 30.cm. cover. of. compacted.inert. material,. and. then. soil. and. other.
ill. material. of. suficient. depth. to. enable. root. development.. While. milled.
oxide.ore.and.waste.rock.could.provide.a.large.part.of.the.latter,.clay.is.not.
locally.available..With.a.general.preference.for.revegetation.with.native.“box.
and. ironbark”. species. a. relatively. thick. cover,. of. minimum. 1.m,. would. be.
required,.although.little.research.has.been.undertaken.into.such.rehabilita-
tion.and.it.is.unlikely.to.be.successful.on.a.potentially.intermittently.water-
logged.cover.resulting.from.the.impermeable.clay.
Experimental Facilities
Field. experimentation. at. Stawell. Gold. Mine. was. designed. to. provide. an.
alternative. rehabilitation. strategy. for. the. TSF. (Tailings. Dam. No.. 2). that. is.
cost-effective.while.ensuring.minimal.environmental.impact.from.release.of.
acidic.and.contaminated.drainage..The.continuous.deposition.of.tailings.and.
regular.uplifts.of.Tailings.Dam.No..2.precluded. in situ .experimentation.into.
rehabilitation.. Instead,. two. separate. small. tailings. repositories. were. con-
structed..A.irst,.small.impoundment.constructed.on.the.northern.margin.of.
Tailings.Dam.No..2.in.March.2001.was.illed.to.a.depth.of.2.m.by.the.pouring.
of.5700.m 3 .of.sulidic.basaltic.ore.tailings..The.prototype.structure,.measur-
ing. approximately. 200.m.×.25.m,. was. allowed. to. drain. for. 6. weeks. prior. to.
creating.experimental.cover.plots.
Construction.of. a. larger. TERF. was. commenced.in. September. 2001.upon.
the. surface. of. an. older. TSF. (Tailings. Dam. No.. 1). with. the. aim. of. provid-
ing.a.physical.and.geochemical.environment.similar.to.that.envisaged.at.the.
time.of.rehabilitation.of.the.current.TSF.(Figure.20.2).. In situ .surface.tailings.
were.bulldozed.to.form.∼3.m.high.walls.of.two.experimental.cells.each.with.
dimensions. of. 75.×.155.m.. Fresh. sulidic. tailings. were. poured. in. the. same.
manner.as.in.the.current.TSF.from.spigots.positioned.around.the.periphery.
of.each.cell..Filling.of.TERF.took.4.months.and.was.completed.in.May.2002..