Austria (2006)

In 2006, on behalf of the London Company, Hanson PLC, we carried out the verification of the reserves of twenty exploited and as-yet unexploited deposits of stone, gravel and quartz sand, situated in the wider surroundings of Linz (in the Province of Upper Austria). This work was carried out as one basis for the takeover of the Quarzsand GmbH Eferding Company, a leading miner of raw construction materials and a producer of building materials in the area of interest. The implementation of the task was carried out in cooperation with Austrian colleagues who ensured the geological and exploration work in respect of the Austrian legislature.

The goal of the project was to provide comprehensive information concerning the raw material potential of the company, to assess the standard and the completeness of the geological and the mine-survey documentation, to assess the methodology of the previous stages of the survey and the calculation of the reserves, on the basis of independent calculation to verify the credibility of the reported reserves and to assess and randomly check the quality of both the raw materials and the manufactured products. At the sites selected control sampling of the raw materials was carried out from mining walls. In the areas with reported reserves in the forefront of the mining sites and at some as-yet unmined sites, the deposit’s inspection boreholes had been designed in relation to the existing reconnaissance network. Their purpose was to verify the reported thickness of the deposit, the stripping conditions and the quality of the raw materials while at the same time providing new information concerning the deposit and its hydrogeological condition. The drilling works were carried out by the Insond Spezialtiefbau Ges.m.b.H. Company from Vienna, using a Wirth ECO 1 drilling rig, which also guaranteed an excellent yield of the material from the saturated parts of the deposit.

Geologically, the area of interest included:

• the southern margin of the Bohemian Massif in the area south of the Danube River with old Palaeozoic granitoids and gneisses mined for the production of crushed stone;
• mollase sediments of the Alpine foredeep with deposits of slightly/partially consolidated quartz sand (Linzer Sand) of the early Tertiary age/era (Upper Oligocene), the overburden and bedrock of which is built-up by "blisters", i.e. slightly consolidated layered calcareous clays with positions of fine sand; the subject of mining at one of the sites is the coarser development of mollase sediments into the form of gravel;
• sand and gravel from the Danube terrace system of Quaternary age (Pleistocene) for dry extraction and also for extraction from water.

The fieldwork included reconnaissance and photographic documentation of the individual mining sites and the as-yet unmined sites, the processing of documentation points, documentation of the drill core and the sampling. Laboratory work was carried out in the Czech Republic in the Testing plant for stone and aggregates in Hořice and in the laboratory of the company Martin Janda - Geologie a geotechnika based in Křemže. Mineralogical and petrological evaluation was carried out at the Institute of Geology of the AS CR, in collaboration with the Institute of Chemical Technology in Prague. The documentation of the work undertaken and the results of the tasks were concentrated in the final report that also included the control calculation of the reserves, their overall evaluation and also relevant recommendations.