Jerry S. Kuma

Expanding the hydrogeological base in mining EIA studies: A focus on Ghana

Abstract Conducive economic policies have led to a vibrant minerals and mining sector in Ghana, with the establishment of 12 new large-scale gold mines since 1988. The Environmental Protection Agency (EPA) has been strengthened and a robust monitoring regime is in place to prevent abuse of the environment. Insufficient attention has been paid, however, to the necessary hydrogeological detail of statutory environmental impact assessments (EIAs). This should be specified in order to furnish concise knowledge of the pre-mining groundwater conditions. Although such information is normally obtained through pumping tests, the cost involved has hitherto precluded its use. Yet hydrogeological data can be estimated from thin section and other studies on borehole cores obtained during routine mineral exploration. Combined with other “regional” methods of gathering groundwater information, these estimates provide a sound basis for baseline condition evaluation for less than 0.1% of the average expenditure incurred in locating an economic deposit. Apart from improving mining EIA practices, the proposed approach can also yield dividends for the mine operator, in terms of helping to find water for mine needs, and minimising water ingress to workings and associated pollutant release.

Open Pit Mining and Land Use Changes: An Example from Bogosu-Prestea Area, South West Ghana

The Bogoso‐Prestea area has experienced mining for over a century and with advances in mineral processing and the promulgation of a new Mining and Mineral Law in 1986, surface mining became viable. High demand for gold will lead to increase in mining activities which will result in land use changes. Estimation of areas and analysis of land use flows methods were employed over a twenty year period (1986 – 2006) to evaluate areas within the Golden Star Resources Bogoso Prestea Limited (GSRBPL) concession that have experienced land use change due to mining. The study revealed that mining in the area increased by 12.1 % in land coverage from 4.69 ha in 1986 to 530.84 ha in 2006. Agricultural land use reduced from 97.8% in 1986 to 82.7% in 2006. A significant rural – urban migration was acknowledged because settlements increased from 0.45 % in 1986 to 4.95 % in 2006. The study also revealed that land use due to mining stabilised between 1996 and 2006 due to good reclamation practices and reduced mine development.

Hydrogeological framework for assessing the possible environmental impacts of large-scale gold mines

Abstract Hydrogeological information is crucial to the development of a sound environmental impact assessment (EIA) for a proposed mine, as well as the management of potential environmental impacts during and after exploitation. However, the determination of hydrogeological parameters is not customarily included in mineral exploration surveys, with the result that many EIAs end up being rather light in hydrogeological content. Examples from the Tarkwa gold mining district of Ghana illustrate this point. Consequences of such an inadequate hydrogeological understanding are potentially serious, ranging from an inability to predict future problems in water quality after the cessation of mining, to a lack of understanding of hydrogeological controls on slope stability, which is arguably manifest in the catastrophic spill of cyanide-rich processing effluents from a breached tailings dam at Wassa West, near Tarkwa, on 16 October 2001. To redress this deficiency, we propose that a hydrogeological database be assembled during the mineral exploration phase, according to a specified protocol (‘check-list’). Using these data, a rational conceptual hydrogeological model for the mine site and its surrounding area can be developed, providing the basis for a thorough consideration of groundwater aspects within the statutory Environmental Impact Assessment, which is (as in most other countries) required by Ghanaian government statute before a mining lease is approved. The resources required to set-up such a database are small compared to the benefits.

A suggested solution to the blind zone problem in shallow exploration surveys

Abstract The blind zone in exploration using the refraction method is one which exists in practice and therefore has to be carefully considered in the solution of any shallow exploration studies using the seismic refration method. This case study presents problems encountered due to the occurrence of a blind zone during a tailings dump evaluation in which the refraction method was employed and suggests a solution to the problem. The solution works well in situations where the velocity of the hidden layer approximately equals that of the overlying layer. The results of depths computed using the method were compared with those obtained from drilling and they yield very satisfactory reliability.

Modelling PGIS for Multipurpose Cadastre in Ghana

Cadastre is the pivot of the Land Administration (LA) system, and it describes the right, restrictions and responsibilities (RRRs) associated with land (Njuki 2001). The current cadastre system package is made up of the following: a cadastral plan (geometric dimension of the parcel), the interest, right (ownership), and values. Other vital information such as cultural attribute, physical attribute, utility data, and legal attributes are not considered. Though no one can claim absolute ownership of land, every individual traces a lineage to land. This means that every one owns right to land with respect to and in accordance with the local laws, practice and encumbrances. Multipurpose Cadastre which combines geospatial data to cultural, physical and legal attributes with utility data through technical integration is very essential for developing countries like Ghana. The model has a potential to support spatially enabled government, private sectors, society and to expand Information Technology Communication (ICT) support in the process of visualization, organization and management of useful land information (Bin Taib 2012). Figure 15.1 illustrates the potentials of MPC.

THE PROPOSED ALUMINA INDUSTRY AND HOW TO MITIGATE THE RED MUD FOOTPRINT IN GHANA (doi: 10.4090/juee.2012.v6n2.048056)

During animal waste agricultural applications, the major concern is the pathogen spreading, which may contaminate groundwater. Colloid release and pathogen transport during irrigation were evaluated in intact agricultural soil columns in this research using Escherichia coli as a model strain. In order to be easily identified and quantified, E. coli was incorporated with green fluorescent protein genes. The experiments were conducted at a water flow rate of 100 ml/min and the elution was collected and analized for colloid release and E. coli transport. Colloid release and E. coli transport were simulated using an implicit, finite-difference scheme with colloid release rate coefficient and E. coli deposition rate coefficient as constant, linear and exponential functions of the soil depth, respectively. It seemed that exponential functions had the best fit against the colloid release and E. coli transport observations.Niger Delta Estuary Nigeria is influenced by tidal currents due to its proximity to the Atlantic Ocean. Tides in the region are mostly semidiurnal, having two high and low water levels each day, with tidal prism ranging from 0.4 to 1.5m. The effects of tidal current reduces with distance inland and are strongest at the inlets with velocity varying from 2.0 to 5.0m/sec. The depth of the Estuary Rivers is controlled by the strength of the tidal currents; areas very close to ocean with stronger tidal effect are very deep; while shallow rivers predominates the hub of the estuary. Tidal current provides the steady supply of energy that moves sediments in and out of the estuaries from the seashore thus determing river bathymetric shapes through modification of existing morphology by eroding or depositing of sediments along the river course, while further sediment deposition is curtailed at the bottom as the estuary gets shallower due to the increasing stirring by waves. Despite all the sediment coming into the estuaries, many canals in the region have remained as open-water bodies, even after some thousand years. This suggests that, the interaction between the tide and the shape of the canal floor helps to regulate long-term sedimentation. However, the Dredged Canals in the Niger Delta estuaries have suffered high siltation rates because of excessive supply of sediments generated by storm/flood waters from upland and disposal of spoils from dredging activities into the water bodies, which causes some imbalance in the estuarine self-cleaning mechanism. Sediment loads entering the mangrove swamp environment are essentially polycentric; suspended fines enter the system both from the sea and the rivers. A mathematical model was formulated to predict and study the behavior of the sea bed levels, tidal heights and currents, in other to understand how they interact with each other. The model was calibrated using data obtained from local field observations and measurements. The model results compares favorably with the field results, with average correlation coefficient of 0.9 (see figures 2-13).The result showed that Niger Delta estuaries erode, accrete, or remain stable, depending on the rate at which sediment is supplied or removed from them by flood waters and tidal currents.Domestic sewage treatment experiments were conducted in trickling filters in laboratory pilot plants in which the peeled dehydrated fruits of Luffa cyllindrica were used as a support medium for microbiological growth, in order to verify its capacity to remove organic matter, measured in terms of Biochemical Oxygen Demand (BOD5,20) and Chemical Oxygen Demand (COD). Other parameters such as suspended and settleable solids were also measured. The results obtained, when compared to results from similar pilot plant using stones as supporting medium, and with the removals predicted by classic formulas used for trickling filters design, indicated that this support medium may substitute with advantages, under specific conditions, the traditional support media. Further studies are recommended.The wastewater treatment station (WWTS) by wetlands consists of a physic-biological system with part of the filtering formed by plants and projected according to the filtering soil principle. The elements that constitute the medium, in this case the soil, microorganisms and plants, are responsible for the organic matter and the sewage odor compounds degradation. This study employed the static and dynamic olfactometry methodologies to evaluate the treated effluents odor removal in two stations by root-zone wetlands in rural communities in Irati (PR). Olfactometry results were compared to the effluents physic-chemical analysis, and parameters such as dissolved oxygen (DO), chemical oxygen demand (COD) and pH were taken into account. Results revealed DO increase and COD removal in the treated effluents. Olfactometric analyses pointed to noticeable levels of odor in the treated effluents; however, there was significant reduction in the odor intensity of exit effluents in relation to the entrance ones. In general, the wastewater treatment station through wetlands showed efficient to the removal of odor compounds, as well as the removal or organic matter from the medium.

Surface Deformation Monitoring in the Goldfields Ghana Limited Area.

Large sets of remotely sensed data can be acquired using satellite communication technology and processed using high performance computers to produce interpreted images of objects on earth. The rapid advancement of remote sensing techniques has enabled these satellites to acquire data of large areas within a relatively short period. This study investigated the application of remote sensing imagery from two different platforms in monitoring land surface deformation in the Goldfields Ghana Limited Tarkwa, area. The results showed that both DInSAR and Intensity Difference Analysis are able to identify land surface deformation due to surface mining. However, it was not possible to pinpoint the location of slope failure without the knowledge of the incident.

RUNOFF ESTIMATES INTO THE WEIJA RESERVOIR AND ITS IMPLICATIONS FOR WATER SUPPLY TO THE ACCRA AREA, GHANA (doi: 10.4090/juee.2008.v2n2.033040)

Accra has a population of about 2.3 million and is supplied with water from both the Kpong and Weija Water Works. Water from the Weija treatment plant is taken from the Weija Reservoir which is fed by Rivers in the Densu River Basin (DRB) that flow into the Reservoir at Weija. With increasing annual population growth of Accra at 4.4% and inadequate water supply to it, this study has examined the hydrological data available on the Weija Reservoir from 1980 to 2007 in an attempt to estimate runoff into the Reservoir with the view of determining whether water is available to meet its present and future demands. Results show that even though water abstraction from the Reservoir has increased almost four times since 1980, to more than 67 million m3/year in 2007, and a maximum runoff of 7.97 ± 0.21 × 10-2 km3/year was estimated in 2005, this value is less than the true runoff into the Reservoir. It was also observed that potential evapotranspiration has increased by 0.14% while precipitation has decreased by 0.93% in the DRB, indicating that runoff from the Basin into the Reservoir is probably decreasing, albeit slowly. Additionally, fishing and waste disposal methods are poor; land use practices and other anthropogenic activities in the DRB pose a threat to the sustainability of the Reservoir. Serious educational programmes and enforcement measures need to be urgently adopted to safeguard continuous water flow into the Reservoir. Proper hydrological data collection and data management practices are recommended for the Reservoir and Densu River Basin if detailed planning of the water resources of the Reservoir are to be achieved.Land use and changes in land cover play an important role in local and regional climatic conditions, especially in tropical regions. Piracicaba, a city in southeastern Brazil, has an economy that is based primarily on sugar cane cultivation. The seasonality of this crop means that there are marked annual fluctuations in land use and cover in this municipality. In this work, we investigated the seasonal variation in urban heat-islands and local climatic variations by using remote sensing data, geographic information system (GIS) and atmospheric modeling. The urban heat-islands were analyzed by using Landsat 7 (Enhanced Thematic Mapper+) images for the sugar cane crop (January to March) and non-crop (August to November) periods, and these images were subsequently converted to land surface brightness temperature. The average temperature in the non-crop period was 3.5°C higher than in the crop period, which suggested that heat-island intensity may be linked to the seasonality of sugar cane cultivation. In order to examine the influence of urban areas on regional temperature changes and heat fluxes, numerical simulations were done with the Brazilian Regional Atmospheric Modeling System (BRAMS). Overall, the results obtained suggested that local and regional climatic dynamics were related to land use and changes in land cover.The environmental conditions in Brazil have been contributing to the development of anaerobic systems in the treatment of wastewaters, especially UASB reactors – Up flow Anaerobic Sludge Blanket. The classic biological process, for removal of nutrients, use three reactors - Bardenpho System, therefore, this work intends an alternative system, where the anaerobic digestion and the denitrification happen in the same reactor, in this system, is reduced for two, the number of reactors. The experimental system was constituted by two units: first was a nitrification reactor with 35L volume and 15 days of sludge age. This system was feed with raw sanitary waste. Second unit was an Up flow Anaerobic Sludge Blanket (UASB), with 7.8 L and 6 hours of hydraulic detention time, feed with ¾ of effluent nitrification reactor and ¼ of raw sanitary waste. This work had as objective evaluates the performance of the UASB reactor, in terms of removal efficiency, of bath COD and nitrogen. It was verified that the anaerobic digestion process was not affected, the removal efficiency of organic material expressed in COD, was 71%, removal already expected for a reactor of this type. It was also observed that the denitrification process happened; the removal nitrate efficiency was 90%. Therefore, the denitrification process in reactor UASB is viable