GEOLOGY AND THE QUARRY INDUSTRY WITH SPECIAL FOCUS ON THE SELECTION OF A SITE FOR A NEW QUARRY
by
WINSTON TADDIUS RAJPAULSINGH, CONSULTING GEOLOGIST

ABSTRACT

The use of geological studies in the selection of a new site for quarrying provides a means of estimating the quantity, quality and possible use of the rocks to be quarried.

The methods employed include literature search, reconnaissance or detailed field mapping in the exploratory phase, and later, evaluating trends of rock-bodies in order to guide extraction during the operations phase. Geological studies account for 21% of the total input of various disciplines in the different quarry phases.

Finally, in Trinidad and Tobago, there is need for a coherent and comprehensive geological database pertaining to the quarry industry.

INTRODUCTION

Geology is the foundation stone of the quarry industry. Elucidating the rock types of the earth's crust is the essence of the discipline - geology.
Quarrying is the open or surface extraction process of rock materials that are useful to mankind.

The initial start-up phase of any quarry is totally dependent on the geology. In this exploration stage, the type or types, the estimate of quantity, the quality, and the possible uses of the rocks encountered, are all the work of geology.

Overall considerations of conservation, pollution, access, land use, demand and market values, and manual/mechanical layout of proposed development all fall under the ambit of geology when considering the initial viability of a new Quarry project.

The development of the quarry industry is directly proportional to the amount of geological input in the areas identified for quarrying. In Trinidad and Tobago, it has been unfortunate so far, that no comprehensive, planned geological surveys have been carried out on areas identified for quarrying. In effect, quarries have been developed which then lend to geological information. The end result being an antiquated, haphazard, industrial development.

GEOLOGY AND THE QUARRY INDUSTRY

From the initial to the final set-up of a Quarry Plant, three important phases are recognised. They are exploration, planning and development, and operations entities. Geology, as one of the disciplines of study and work in the Quarry Industry, plays a significant part in the exploration stage. Its role is reduced in the planning, and development phase. However, in the operations stage, although still secondary, it should be kept as an important part of the trendology of the extraction of rock materials.

Table 1 shows the role of Geology in the Quarry Industry with respect to the other disciplines.
SELECTION OF A SITE FOR A NEW QUARRY

In establishing whether an identified land area has potential for the development of a new quarry, it is necessary to firstly carry out a Literature/ report search.
If there is geological information, then a surface geological survey is conducted to check and update, if necessary, the geological report. A t the same time, a survey plan of the land area is needed to define boundaries outlining the exact area to be surveyed geologically. The definition of these boundaries and the resulting survey plan are the work of the land surveyor.
If there is no geological information, then a full surface geological field survey is conducted to determine the rock types on the boundary surveyed land area.
When the surface rock exposures are known and mapped, then each rock type is evaluated on merit of its potential uses and market demand. Selection or non-selection is then made for further examination of rock types.

If the rock types encountered are suitable for quarrying then more detailed surface geological techniques and sub-surface geological investigations are employed to find out the quantitative volumetric estimate of the rock resource. Herewith, samples are retrieved for physical, chemical and petrographic laboratory analyses to determine the quality of the rock resource. The quality defines and confirms potential usage and market values.
With the quantity and quality surveys, detailed financial viability of a quarry project could be then carried out. All engineering input in planning disciplines are needed here for and development.
Figure 1 is a flow diagram showing steps in the selection of a site for a new quarry.