River mining: alluvial mining of aggregates in Costa Rica. (CR/03/050N).

Abstract

This report is one of a series of Technical Reports on alluvial mining in developing countries, most of which relate to Jamaica (see Preface for details). They are the output from the 'Effective Development of River Mining' project which aims to provide effective mechanisms for the control of sand and gravel mining operations in order to protect local communities, to reduce environmental degradation and to facilitate long-term rational and sustainable use of the natural resource base. The work was carried out under the Department for International Development Knowledge and Research programme, as part of the British Government's programme of aid to developing countries. The project was undertaken in collaboration with key organisations in Jamaica and Costa Rica, who provided field guidance and local support

In recent years, land-use conflicts, environmental restrictions, resource depletion and a desire for consistent supplies of high quality aggregates in Costa Rica have resulted in changes to the pattern of supply of aggregates, with increased contributions of alluvial sand and gravel from instream extraction (alluvial mining).

In Costa Rica, alluvial mining represents a source of good quality sand and gravel with wide distribution, practically inexhaustible resources, easy extraction, and simple processing requirements. However, their generally distant location from the Great Metropolitan Area and the high costs of transportation, limit resource development. Nevertheless, there are many rivers which supply sand and gravel, particularly in the Atlantic region. Distribution is mainly by lorry, but some material from the Barranca river is also transported to San Jose by the recently reopened railroad system.

Alluvial extraction in Costa Rica is carried out by numerous small companies using unskilled or semi-skilled labour. Quarry operations have a short life involving simple extraction and processing procedures. This report describes the environmental impacts associated with the mining, processing and transportation of alluvial sand and gravel in Costa Rica.

In Costa Rica, a specified volume of material may be extracted from a river, based on calculations of the material that potentially could be replenished, a concept termed the 'replacement volume' or 'dynamic reserves' of the river. However, currently a standardised systematic procedure for calculating such volumes does not exist.

The concept of 'environmental recovery' is considered as a means of systematic control of the river mining operations. Mineral licences should identify and execute mitigation measures which favour processes of natural regeneration or recovery, diminishing negative impacts on the environment. However, in areas of alluvial mining activity in Costa Rica, restoration schemes are uncommon. The most relevant experiences of alluvial recovery have been developed by the Costa Rican Institute of Electricity (ICE) during the construction of hydroelectric power plants. Based on these experiences, ICE specialists have listed a number of activities which need consideration and whose prioritisation depends on the stage of the development (before extraction, during extraction, and post extraction) and on the particular environmental conditions of each river section.

The report also presents a review of current mining and environmental legislation in Costa Rica including specific alluvial mining legislation, the management structure regarding alluvial mining licences, and the requirements for environmental impact studies. Recommendations propose future regulatory reform and improved management practices in order to promote the alluvial extraction industry.

This report is available to download in full colour (6142 kb) and in black and white (6142 kb).

Citation

F Alvarado-Villalon; Harrison, D.J.; Steadman, E.J. River mining: alluvial mining of aggregates in Costa Rica. (CR/03/050N). (2003)

River mining: alluvial mining of aggregates in Costa Rica. (CR/03/050N).

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