The Jalicot group, which operates the Solignac-sur-Loire basalt quarry, invited the general public to come and discover its facilities, its professions and its activities, all day Saturday. A circuit punctuated by several points of interest had been imagined by the teams in place. On the program: discovery of the geological environment, extraction techniques and local fauna and flora.
What is hidden along the D 27, when you head towards Chadron from Solignac? Behind a slope topped with a chaotic forest of deciduous trees, there is an industrial site that is almost unique in the department. An 18-hectare estate, surrounded by farmland to the south and wooded nature to the north. To find out more, you had to be there on Saturday morning for the open day organized by the Jalicot group.
The company operates the open-air quarry located overlooking the Loire, not far from the villages of Mussic and Collandre. There, on a site fragmented by land acquisition constraints, nearly 100,000 tons of materials are extracted each year.
The blocks of material, detached by blasts (one every two months), are then transported by truck to the facilities which enable the production of aggregates.The “tile” of the Solignac quarry, where part of the stocks of aggregates, the work equipment and some blocks that need to be roughed out are located. Photo Cédric Dedieu
The mining work is subcontracted to a specialist company. After drilling (to a depth adapted to the needs), the company Exploroc is responsible for firing with nitrate/fuel oil-based cartridges. During these operations, a specific information display is placed at the entrance gate and lookouts are present on the heights of the site.
At present, the main extraction pit consists of two levels 15 metres high, to which a third and final level of 15 metres will soon be added (below this there is no more interesting material).
Half a dozen machines are permanently present on the site: two dumpers to transport the materials, two mechanical excavators for extracting and loading the trucks, as well as two loaders to evacuate the aggregates and load the customers. All the extracted elements are worked, crushed, sieved in order to obtain different cuts: gravel, sand, gravel, etc. The machine settings are adjusted according to the needs of the customers.
At the base of all the major engineering structures built as part of the Puy bypass
The different classes of aggregates are stored on site (currently 50,000 tonnes), before being marketed. The customers are mainly local, for public works (roads), construction, a concrete plant (in Chaspuzac), etc.
The basalt extracted in Solignac-sur-Loire is a massive rock, resulting from a volcanic eruption that took place several million years ago. As it cooled, this lava flow solidified to give body to the famous basalt organs that can be observed almost everywhere in Haute-Loire.
As far as Switzerland, for the benefit of a naval base
Today, the quality of the basalt sand extracted in Solignac is unanimously recognized. As proof, it is the basis of all the major engineering structures that have been built as part of the Puy bypass: Taulhac viaduct, covered trench, etc. “In this specific area, we still have a slight lead over our competitors. In terms of hardness, if we take the example of the piles of the Taulhac viaduct, concrete made from basalt sand has nothing to envy of concrete made from alluvial sand,” confirms Joachim de Araujo, quarry manager.
Another sign of the interest that construction professionals have in Solignac basalt: one of the French specialists in prefabricated concrete, the Parisian company Bonna Sabla, comes to collect 4/6 mm crushed sand and gravel from the quarry. Joachim de Araujo recalls having supplied 6/10 mm in Switzerland, for the benefit of a naval base for submarines.
They had tested several quarries and what suited them best was the materials from Solignac.
Finally, we can mention the Lidl brands, whose car parks are often made from Velave aggregates.
In 2017, the Jalicot company was granted an extension of its operating permit until 2032 by prefectural decree. The site seems to have a bright future, if we consider the annual needs for aggregates in France. Each person “consumes” nearly 5.5 tons of materials per year, through roads, concrete, civil engineering infrastructure, eyeglass frames, bodywork and mobile phones.
But before expanding a quarry, or even opening it, it is essential to carry out destructive or core drilling and to conduct geophysical campaigns. This is what was undertaken in Solignac, where electrical signals were sent into the ground to obtain resistivities (specific resistance of a substance) and define the types of materials present. It is also important to know the thickness of the deposit, in order to determine its volume (its potential). The exploitation of the site is subject to authorization from the State.
In this sense, a heavy file must be submitted to the competent services. It includes in particular a chapter “site restoration”. In Solignac, partial backfilling is thus planned, with materials from the discovery of basalt and – on the margins – external earthworks materials. To favor biodiversity, there will also be a landscaping component, entrusted to a specialized company. Plans have already been drawn up and low walls have been erected to accommodate a hedge plantation.
Cedric Dedieu
Work on biodiversity with the CPIE Clermont-Dômes
As part of its regulatory obligations, the Jalicot company works throughout the year with the CPIE Clermont-Dômes, in order to monitor and promote biodiversity in the quarry.
All “quarry” type operations are subject to a prefectural decree which provides for the implementation of monitoring and compensation measures.
Associative structures such as the CPIE (Permanent Center for Environmental Initiatives) Clermont-Dômes are intended to support operators in implementing these measures. “It is also a question of acculturating the people concerned to ecological and environmental issues,” explains Laurent Longchambon. To summarize, there is a regulatory part that requires action and a proactive part developed by the Jalicot company, which wishes to raise awareness among its various agents and services.”An educational exhibition was presented to the public on Saturday.
The Solignac quarry is enclosed in a forest environment, with agricultural areas on the southern plateau and the Loire below. This location is very favorable to the diversity of species, insects (crickets), reptiles (vipers, snakes, grass snakes), amphibians (natterjack toads), birds (kestrels), mammals, etc. The exploitation of the quarry modifies this environment and, paradoxically, also generates new ones, favorable to biodiversity: “The extraction activity creates pioneer environments that diversify species. However, we should not make quarries to try to protect these species adapted to pioneer environments.”
Ultimately, it is difficult to say whether the balance between displaced or lost species and new species installed is balanced. We are talking more about a “plural” balance linked to temporary diversification.
Schoolchildren visited the site
The quarry operator had also invited schoolchildren from Solignac the day before its open day. In the morning, 24 elementary and middle school students from the private school came to visit the site. In the afternoon, the public school was present with around forty pupils (including CE and CM). The children were able to follow the discovery trail between the extraction pit and the crushing/screening facilities. They were also very interested in the chapter dedicated to fauna and flora, with a “hunt” for insects and small animals which was very popular.
