Includes specialized enterprises in sand washing operations (of all kinds and purified from the impurities, whether glass, metal, plastic or other to be used as raw material in the manufacture of products) or to build on these operations take place separately from the sites of the sand are extracted and intervention in these processes, transport of sand from places extracted to the factory, as well as transferred to places used after washed up on the WEBSERVER that none of these operations carried out separately paid or subcontracts