Environmental Impacts of Geomaterials Exploitation in the Republic of Congo

Abstract

Geomaterials are extracted everywhere in Congo, generally without environmental and social impact studies. The objective of this study was to assess their exploitation and the associated environmental consequences. Data were collected through interviews and field surveys. A total of 163 quarry sites (17% industrial and 83% artisanal) were studied, with an annual production of nearly 52 million tons. The activity is carried out either in the open air or in water. Three types of materials are exploited: soft (65%), hard (35%) and smooth (0.1%). The activity is mainly centered around urban agglomerations, and sand and gravel are the most prized geomaterials, regardless of the type of exploitation. The geomaterials exploited come either from primary rocks (granite and quartzite) or from the products of their dismantling (accumulations of gravel, sandstone, recent sands or laterites). The various mining processes use, from extraction to finishing, incoming flows in the form of consumable materials (oils, greases, tires, etc.), in the form of energy (fuel, electricity, etc.), and in the form of water, in the form of energy (hydrocarbons, engines or explosives), water and outflows in the form of solid (abandoned gravel heaps), atmospheric (dust, gas, vapors) and liquid (lubricants, fuels, water for washing materials) discharges that induce various pollutions that affect all the compartments of the environment (physical environment, biodiversity, health and human well-being). The impacts of artisanal mining are mostly medium and minor, with only 18% of major impacts, in contrast to industrial mining, which generates 55% of major impacts and appears to be the most degrading for the environment. Despite of the legislative and regulatory texts, the exploitation sites are abandoned without any rehabilitation, which impacts the environment for a long time. To impulse a sustainable management of the activity, proposals have been made.