The quarrying industry in the Maltese Islands - Josianne Vassallo

Introduction

Limestone rocks are the only mineral resource in the Maltese Islands. Various archaeological sites dating from the Neolithic period, show that limestone has always been an important resource for building purposes. With a population density of 1,194 persons per square kilometre (Government of Malta, 1996) - total surface area being 316 square kilometres. Malta is one of the most densely populated countries in the world.

The intensification of quarrying resulted from the need to supply the increasing limestone demands for the island’s building industry. The expansion of built-up areas has been immense. The total built-up area of the islands increased from 5 per cent in 1957 to 16 per cent in 1985. The last Ordnance Survey of the islands in 1983, revealed that in the south of Malta, quarrying increased by approximately 200 to 300 per cent (Balm, 1996).

Types of Quarrying

Two types of limestone rocks are quarried (all Maltese quarries are open cast):

Softstone Quarries

Softsone (locally also known as ‘Franka’), which is quarried from the soft yellow layers of the Lower Globigerina Limestone, is the main building material for construction. Extraction takes place by cutting the limestone with saws into blocks of standard sizes. Softstone quarries have large vertical-sided faces, and usually have a depth between 30 to 60 metres (Government of Malta, Technical Report 5.3, 1991). The quality of the stone decreases with depth. Over time, softstone gets harder as it dries and weathers (Balm, 1996). Existing quarries have reached their land limits and are extracting at deeper levels, while older softstone shallow quarries are being reopened for deeper exploitation.

Hardstone Quarries

Hardstone is quarried from the harder Lower and Upper Coralline Limestone through drilling and blasting. These deposits produce marble like material, crushed aggregates or spalls. The latter two are processed in crushers and screening plants, and used for road construction and concrete. Hardstone quarries can contain a harder variety of limestone, popularly known as Malta Marble; this can be polished and used for tiling. Hard rock is graded in two types:

1. hard and non porous, resistant to weathering; and
2. soft and porous, less resistant to weathering (Government of Malta, Technical Report 5.3, 1991).

Both types can be found in a single quarry. The impacts of quarrying on the natural environment quarries have a negative visual impact in the Maltese Islands. Quarrying is taking place in environmental sensitive areas such as valleys and along the coastal zone. Wied Filep disappeared completely due to quarrying. Flora and fauna are being endangered. Quarrying in a local valley was responsible for the extinction of the Late Spider Orchid (Ophrys oxyrrhynchos) (Balm, 1996), which was endemic to Sicily, Sardinia and Malta (Lanfranco, 1989). Other quarries are located in areas of archaeological importance. Explosives used in hardstone quarrying are threatening the stability of valley slopes and will cause structural damages to the archaeological temple sites of Mnajdra and Hagar Qim (Balm, 1996).

In 1986, the Works Department stopped issuing permits for new quarry sites, however quarry extension was allowed to continue. The Government of Malta published The Structure Plan for the Maltese Islands (1990), a policy document issued to develop and co-ordinate a strategic plan for the island’s land uses. Although the plan stated that Malta was self-sufficient in limestone building materials, it did not specify what can be done to monitor and control quarrying.

Disused Quarries

Most worked out quarries are left abandoned without reclamation. Table 1 shows the extent of areas affected by quarrying outlining operating, derelict and restored quarry sites, in 1988.

Table 1. Extent of areas affected by quarrying in 1988.

Source: Government of Malta, Malta Structure Plan - Technical Report No. 5.3: Survey on Quarries, (1991), p. 44.

Technical Report No. 5.3 on quarries (1991, p. 51), identifies eight possible afteruses for quarry rehabilitation:

1. agriculture;
2. forestry;
3. built development;
4. sport and intensive recreation;
5. non intensive recreation and country park;
6. wildlife, conservation and education;
7. water storage and supply; and
   land filled waste disposal.

Conclusion

During 1997, debates on waste management took place in the Maltese Islands. Construction debris, which is the greatest waste generator on the islands, generates about two million tons of waste material annually. The Government suggested that disused quarries could serve as dumping sites for well sorted and thoroughly inspected construction debris. This debris can eventually be used for the reclamation of disused quarries. A vision for the future of the quarrying industry would include an enforced management plan that works within the lines of the principle of sustainable development for such a finite resource.