It would seem simple. Some construction sites have an excess of material, others have insufficient. So why can’t they simply exchange these materials? It would be the most sustainable option; avoiding landfill and potentially, unnecessary quarrying of primary aggregates. The Environment Agency and numerous NGO’s actively promote such approaches, and there are a number of mechanisms by which the exchange of surplus materials can take place. But the practice is not as widespread as it should be, largely due to a number of pitfalls surrounding these activities.