Requirements for selecting borrow areas

A borrow area is a place from which soil, sand, gravel or rock is excavated for use in construction (embankments, concrete, road base).

Requirements for selection

1. Quality: suitable grading, strength, durability and soundness; free of organic matter, excess clay, salts and harmful minerals; passes the tests required for its use (embankment fill, concrete aggregate, etc.).
2. Quantity: adequate volume (usually 1.5 to 2 times the requirement) after deducting overburden, waste and the portion under water.
3. Location: close to the site (short haul distance), with easy road access and low transport cost.
4. Ease of excavation: thin overburden, workable slopes, little blasting, and above the water table.
5. Stability and safety: away from landslide, flood and other hazard zones; stable excavated slopes.
6. Legal and social: land ownership and clearance, government permission, compensation, and acceptance by the community.
7. Environment: little damage to forests, farmland, water sources and scenery; the area can be rehabilitated; no effect on river morphology or on structures such as bridges.
8. Drainage and water: no waterlogging, and water available for processing.
9. Economics: low cost of excavation, processing and royalty.

Types of resource

Identified resources thus include the demonstrated and inferred categories, while undiscovered resources are hypothetical or speculative. Each can be economic (reserve) or sub-economic. For construction materials, the sources are also grouped as rock quarries (bedrock aggregate), river-bed and terrace deposits (sand and gravel), and soil borrow pits.