Environmental audit of Prestea Gold Resources, Prestea

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2002-12-12
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An Environmental Audit of the Prestea Underground Mine was undertaken to verify their environmental practices and operations, and identify areas of limitations for redress. The underground environment has been studied as well as the general operations of the mine to assess their impact on the environment. Effluent discharge to the Asuo Kofi stream has been studied extensively. Effluent samples were taken from the plant discharge and along the Asuo Kofi stream and catchments and analysed. Results were compared both with the national guidelines prepared by the Environmental Protection Agency (EPA) and the World Health Organisation (WHO) standards. Drinking water samples were also taken around the mine to verify any possible pollution. Comparison of results was made with Ghana Water Company (GWC) guidelines and WHO standards. A walkthrough audit was also conducted at the various sections and support services of the mine. Recommendation and mitigation measures have been provided. The survey showed that with the exception of the conductivities and the Mg levels, physicochemical pollution of the effluent and stream discharge are generally low. Cyanide levels were high at 160 ppm, dwindling in concentration along the Asuo Kofi stream down to the Ankobra River at 10 ppm. Drinking water was found to be amply wholesome for consumption though with some appreciable levels of iron above Ghana Water Company guidelines and WHO standards in most of the water samples. Water abstracted from underground was considerably polluted with parameters recording values above WHO standards. The only bacteriological parameter analysis also recorded 550 for total coliform (per l00ml) above WHO standards for the water abstracted from underground. At the 150 feet retreat during mine blasting, noise levels recorded indicated 65 dB (A) below standard of 75dB (A). However noise generated during drilling without earplug was high at 95dB (A). Noise level during drilling with earplug was 70 dB (A). There was no available equipment to measure vibrations at the 150 feet retreat, however a personal direct feel indicated a low vibration response. The potential environmental impact of the mine has been identified to be the pollution of the Asuo Kofi stream and finally the Ankobra River, with large deposits of plant tailings both past and present estimated to be about 16 million tons.
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A thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the award of Master of Science degree in Environmental Resource Management, 2002
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