Thirty years ago it was possible to locate a quarry site for crushed rock for concrete aggregate by finding the nearest solid rock bluff accessible by road. But times have changed and the location of a quarry site to furnish crushed rock for concrete aggregate now has’ become rather complicated. Although both sand and gravel can be used for aggregate, this discussion will be confined to crushed rock in the regions around a metropolitan area. Let us assume that a consultant has been retained to advise on the desirability, and the possibility, of opening a new quarry within a given area. The problems are geological and ecological. Since the geological problems are simpler, they will be discussed first.
Generally, the first step is to make a market study of competitive aggregate sources within the projected area. Assuming that the quality of aggregate to be sold by competitors as well as their mining costs will, within narrow limits, be the same, the problem becomes essentially a study of haulage costs from established quarries into the projected new area.
If the market study is favorable, it then becomes desirable to chart the location of those rock types within the area which may meet specifications. But what specifications? Each governmental unit has its own specifications commonly several specifications for aggregates for different uses. Many of the specifications are similar, but the various agencies may differ in the extent to which they force compliance.
It is important to consider mining problems such as (a) topography – can a major rock tonnage be obtained without going below water level; (b) drainage – can pumping be avoided after heavy rains; (c) the amount of stripping; and (d) the availability of areas adjacent to the quarry for crushing, storage, and weighing. Step four obviously will result in a further reduction of suitable areas.