Social-ecological dynamics of aggregate mining in Ouagadougou, Burkina Faso

While traditional materials like clay-based adobe bricks are common in Burkina Faso, rapid urbanization in its capital, Ouagadougou, has driven a shift to more durable construction materials. The city's demand for aggregates - sand, gravel, and crushed stone - is met by several mechanized and artisanal quarries. To assess the scope and processes of these extraction systems as well as the socio-economic and environmental implications of two artisanal granite quarries (Pissy and Yagma) in Ouagadougou, we employed a mixed-methods approach, including truck counts, aerial imagery for 3D volume estimation, interviews, and air quality measurements. Our findings indicate that sand is predominantly sourced from south of Ouagadougou, with transport distances reaching up to 165 km and an extrapolated annual extraction volume of 1.8 million m³, which is relatively low compared to the high urbanization rates and greater volumes extracted in neighboring countries. The 3D model of the Pissy quarry revealed significant terrain alterations and detailed granite extraction data, totaling nearly 450,000 m³. Granite quarrying, predominantly carried out by Burkinabe women with limited education, involves cracking, transporting, and crushing rocks. The artisanal quarries displayed a high level of informality, characterized by lack of regulatory compliance, absence of worker contracts and legal protection, manual and small-scale operations, hazardous working conditions, and economic vulnerability and instability. Air pollution varied, with Pissy exhibiting significantly elevated levels of particulate matter. Policy decisions on the future of these quarries should consider health standards as well as the workers' realities and alternative granite sources.