1887

oa Civil Engineer in South Africa - Seepage and pollution control by proper management of a tailings pond

 

Abstract

This paper presents the results of a series of studies and monitoring evaluation along with remedial construction activities directed toward reducing seepage and pollution migration by the proper use of tailings management. A large tailings impoundment had been constructed and operated for several decades on a river floodplain. Analyses of water samples obtained from the river opposite the impoundment indicated excessive amounts of dissolved, heavy metals entering the river from seepage. To continue operation, the owner was required to reduce contaminant migration to acceptable levels.


Field and laboratory testing were undertaken to determine the geohydrological parameters of the impoundment and groundwater system. From operational record and field observations, the water balance of the impoundment was determined in order to estimate the quantity of seepage escaping from the pound. The water balance was used to verity other methods of seepage analyses, including graphic and computer models.
It was apparent that measures to reduce the concentrations of contaminants at the source were impractical, and that the solution involved reducing the volume of seepage. The technical and economic feasibility of various seepage control measures were assessed. It was concluded that management of the tailings impoundment by means of perimeter tailings beach construction and control of the area of the free water pound would provide effective seepage control at reasonable cost.
The recommended pond management involved only minor changes to existing practice. The impact on operating cost of the milling operation was negligible, with only nominal capital costs involved in some perimeter embankment lining requirements in the vicinity of coarse access dykes to the decant system.

In hierdie verslag word die resultate aangebied van 'n reeks studies en moniteringsevaluerings tesame met herstel-konstruksie-aktiwiteite wat daarop ingestel is om deur die behoorlike toepassing van uitskotbestuur syfering en besoedelingsmigrasie te verminder.


'n Groot uitskotopvangdam is op 'n riviervloedvlakte gebou en vir etlike dekades lang bedryf. Analises van watermonsters wat geneem is uit die rivier regoor die opvangdam het getoon dat uitermatige hoeveelhede opgeloste swaarmetale deur middel van syfering die rivier binnedring. Ten einde met die werksaamheid te kon voortgaan, was die eienaar genoodsaak om die kontaminantmigrasie tot aanneemlike vlakke te verminder.
Veld- en laboratoriumtoetse is uitgevoer om die geohidrouliese parameters van die opvangdam en grondwaterstelsel te bepaal. Die waterbalans van die opvangdam is uit die bedryfsrekords en veldwaarnemings bepaal ten einde die hoeveelheid sydering wat uit die dam ontsnap, te bepaal. Die waterbalans is gebruik om ander metodes van syferingsanalises, insluitend grafiese en rekenaarmodelle te verifieer.
Dit was duidelik dat die maatreëls wat toegepas is om die konsentrasie van kontaminante by die oorsprong te verminder onprakties was en dat die oplossing daarvan die vermindering in die volume van die mate waarin syfering plaasvind, behels. Die tegniese en ekonomiese uitvoerbaarheid van verskeie syferingsbeheermaatreëls is bepaal. Daar is tot die gevolgtrekking gekom dat die beheer van die uitskotte wat opgevang word, met behulp van uitskotstrandkonstruksie op die omtrek en die beheer van die ongebonde waterdam effektiewe syferingsbeheer teen 'n redelike koste sal verskaf.
Die gemiddelde vermindering in syfering deur middel van dambeheer is op ongeveer 90 persent beraam. Beheermaatreëls wat voerings en afsnywalle behels sou slegs 'n marginale mate van meer beheer teen aansienlike hoër koste, verskaf het. Die aanbevole dambeheer het slegs geringe veranderings aan die huidige praktyk behels. Die uitwerking op bedryfskoste van die vergruisingswerksaamhede is gering; daar was slegs nominale kapitaalkoste betrokke waar dit nodig was om 'n voering teen die wal naby die toegangsdyke wat tot die dekanteerstelsel lei te verskaf.

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/content/civeng1/27/2/EJC24977
1985-02-01
2016-12-03
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