During the 1940’s, the United States of America (U.S.A.) contributed significantly to the development of the quarrying industry in Trinidad and Tobago. Large quantities of materials were required for the construction of the United States military bases on leasehold lands located at Wallerfield, Chaguaramas, and Carlsen Fields. One source of these quarried materials came from the area of Verdant Vale to the north of Arima referred to as Scott’s Quarry that is now in the ownership of National Quarries Limestone Division. At the end of World War II, the U.S.A. Forces terminated all quarrying activities but demand for limestone materials for use in road construction continued and the Trinidad and Tobago Government sought to stimulate activity in this industry.
Upon approval of the U.S. Authorities, Government re-opened the quarrying activities at Verdant Vale. However, this was subject to certain conditions. Firstly, all materials extracted from this location had to be used on Government approved projects, and secondly, whenever needed, these lands had to be vacated within two (2) days notice. A third condition specified that a rental fee of TTD 500.00 to be paid monthly from the commencement of quarrying operations.
The contracting firm of Frank de Boehmler was granted a one-year lease of these lands and subsequently he applied for a further term of ten years. However, because of the capital outlay that was needed to develop the lands and the risks of re-possession, financiers refused to invest. Once again, quarrying operations ceased and the lands were put up for auction. A successful bid was made by William H. Scott & Company Limited who then entered into an agreement with a sub contractor Pitt & Quarry Limited to operate the quarry in 1958.
Within the construction sector in the mid 50’s, there were upsurges of quarrying activity arising from the development of large scaled government projects. This continued into the 1960’s when Trinidad & Tobago gained its independence. Its new policy was geared towards industrialization of the country. This level of activity encouraged the development of spin-off industries, namely block manufacturing that produced a new concrete block making a positive impact on the industry by simplifying building techniques. Many concrete batching plants were set up to supply various concrete mixes, and for the prefabrication of pre-cast concrete units. As a result of this increasing demand for aggregates, severe shortages occurred and prices more than doubled.
Supplies of these limestones commonly referred to as ‘blue limestone’ that was in great demand for both concrete and asphalt mixes, were limited. Alternative sources of aggregate were sought. At the time, supplies of sand and gravel, namely the ‘guanapo type’, far exceeded that of limestone. These naturally occurring clastic deposits (in their washed or unwashed state) were developed and exploited for use in the construction sector. During the period 1959 to 1974 production of limestone peaked at 1.02 million cubic yards in 1959 and declined thereafter to a low of 149,000 cubic yards in 1974. Similar trends were experienced for sand and gravel production. As a consequence of the development of these large resources, prices fell relative to that of limestone.
While certain companies within this industry prospered, Pitt & Quarry Limited with a capital investment of over TTD 500,000 in new machinery were still unable to meet the minimum monthly rental. This problem was aggravated by the difficulties encountered at the site. Production was only maintained during the dry season, as the company claimed it was impossible to drill holes for blasting due to the high volume or run-off from the slopes during the rainy season. In addition, the more attractively, low-priced, but inferior quality produced alternative sources were more competitive, and this resulted in severe financial losses for the company.
In August 1965, the company ceased operations and terminated its arrangement with William H. Scott & Company Limited. Its plant and machinery were purchased by the latter company which then entered into a five-yearly, lease agreement with the then Government. Again, the financial situation did not improve. Escalating, extraction and processing costs and the lack of skilled and qualified human resources contributed to the demise of the company. Inevitably, this led to unsafe mining practices.
The period 1973-1982 was a rather interesting era for the petroleum-based economy of Trinidad & Tobago. The sudden increase of crude oil prices in 1973-1974 and 1978-1979 resulted in an upswing in the balance of trade position. With the increased circulation of money and public sector, financing aimed at improving infrastructure, widening the country’s industrial base and enhancing the social welfare program, came increased demand for goods and services. In many sectors demand outstripped supply and this only resulted in rising prices and increasing levels of import.
During this period, the construction sector grew at an annual rate of 9%. The number of active quarries on both state and private lands increased from 75 to 180. Together they provided over 1,000,000 cubic yards of aggregate of which over 60% of this total were removed without authorization from state-owned lands. The need to satisfy this growing demand and make quick profits placed a considerable burden on available plant capacity, the requirements of skilled manpower, the production of high-quality building materials and consumption costs. Inevitably, this led to the production of highly priced, poor quality materials, widespread larceny by quarry operators and unsafe quarrying practices. To elucidate, encroachment by these illegal operations led to the endangering of the fauna and flora of the Aripo Savannas Scientific Reserve; the near destruction of a naturally occurring forest at Manzanilla which acted as a windbreaker against the North-East Trade Winds. In addition, there was widespread pollution of the Caroni River due to the high volumes of effluent that were pumped uncontrolled from quarrying sites.
There was severe contraction of the quarry industry in the 1980’s and the once buoyant economy declined as oil prices began to fall. Since then activities in the construction industry have been curtailed considerably. Joint Venture arrangements with the Alves/MBL Company that was awarded a contract to pave the Piarco Airport Runway failed and the Scott’s Quarry arrangement went into receivership leaving an entire plant and mobile and other operational equipment on site. These equipment were subsequently vandalized.
The Role of National Quarries Company Limited
It is against this background that National Quarries Company Limited, NQCL, was formed in 1979. This state-owned quarry located at Turure in Valencia, (Sand & Gravel Division) in east Trinidad, was established to provide low cost, high quality aggregates for the construction industry. This was to ensure at all times the conservation and maximization of state resources.
At the startup of the company in 1979, National Quarries Company Limited operated with a workforce of eighty (80) skilled and unskilled persons and had a combined plant capacity of 500 tonnes/hour. The company produced and sold an average of 200,000 to 250,000 cubic yards of washed aggregate per annum up to 1985. To effect price control of the market, NQCL sold its products under price control of TTD 26.00 per cubic yard as compared to the average market price of TTD 50.00 per cubic yard in 1980 and TTD 80.00 per cubic yard in 1982.
As part of its planned program for expansion of high quality produced products, NQCL purchased William H. Scott’s financially stricken quarry at Verdant Vale in 1982. This site was earmarked to replace the Turure, Valencia operation of NQCL.
During the 1990’s, there were various approaches to the development of Scott’s Quarry. With most of the equipment vandalized, proposals were made by successive managements. Between 1992 and 1995, proposals were made for using Scott’s Quarry as a bulk provider of limestone as input to crushing plants. However, that failed as well.
Between 1996 to 2000, formal requests for proposals to operate this quarry were advertised. In 2000, a contract was awarded to Roxanne Enterprises, an operator with no quarrying capability that has resulted in circumstances similar to the post World War II years. Escalating, extraction and processing costs, and the lack of skilled and qualified human resources is contributing to the demise of the Contractor operations. It is evident that there is poor engineering and operating practices, inferior products, significant opportunity is being lost to the company. It appears that history has repeated itself.
MINE DESIGN and ENVIRONMENTAL IMPACT ASSESSMENT
It is to be noted, that the first mine design and environmental impact assessment developed for a quarry in Trinidad and Tobago, (Limestone Division at Verdant Vale/ formerly Scott’s) by Sukhu (1987), and published by the University of Wales, was never implemented by the company. The 16 year old Scott’s Quarry Mining Model, Sukhu (1987) has been reviewed, accepted and approved by the current Board of Directors for implementation this year, 2003. The technologies are based upon the current market price being a major factor in the establishment of the final limits of the pit, and therefore a long-range estimate of a conservative basis has been adopted as the design can always be expanded based upon economics. In the past, many quarry operators have ignored this particular aspect of quarrying which resulted in the inefficient management of material extraction and consequently forced down time of processing plants. It has been often said that the primary reason for open pit slope stability studies is to optimize the economics of the pit based on the capability of the rock to remain stable and also to minimize the chances of failures and consequent possible hazards to personnel and operation. Economic advantages of using a mine design at National Quarries are as follows; Current and future market price of the final product can be determined, Production rate and costs can be planned, Limestone reserves can be calculated, Stripping ratios can be determined, and Optimum Rock Blast’s can be performed. The EIA covers all technical aspects of the operation.
The Limestone Division Quarry Project involves open pit mining of limestone aggregates, delivery of limestone feed via a truck and excavator/front end loader operation to the processing plant where it is crushed and screened to the required product grade for the market.
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