German Magazine “Gesteins-Perspektiven” STICHWEH-Drag Scraper in operation
The lake in Palatinate is truly idyllic, with a view over the Hunsrück. No newcomer would suspect that gravel has been quarried here at the heart of this unspoiled nature, in St. Sebastian near Koblenz, for over one hundred years. Already in its third generation, Kaspar Leimig & Sohn Sand- und Kiesbaggerei operates wet dredging here. However, this is barely visible from the outside. Only a striking green oasis with interesting tree population at the heart of the agricultural landscape suggests, from a distance, that another line of business is at work here.
The Leimig gravel pit lies in the area of the Neuwieder Basin, a large-scale structure of the Rhine shale region, where usable sediments are concentrated in the upper eocene due to a tectonic depression. The development of gravel sand extraction through dry excavation was necessary in 1910, for the construction of the neighbouring Urmitz railway line to the north east. Through wet excavation, quaternary gravel terraces are extracted from the alluvial terraces.
Kaspar Leimig, the grandfather of the present proprietor Christoph Leimig, began his work in the gravel pit in 1922. Today, the work is referred to as: Dry mining! Only since 1926 has the gravel sand been also dredged from beneath the water line. In 1934, Kaspar Leimig — after whom today’s company is named — acquired the gravel pit and successively expanded it. At the start of the 1950s his son, Friedrich Leimig, joined the business. Demand grew and the operation was expanded. In 1960 the company informally applied to the water guard office of the Koblenz district administration to perform gravel extraction beneath the groundwater level. The permit was issued by the regional government of Koblenz in February 1962.
In operation: Technology, partly with a legendary status
Throughout the years, the diligent entrepreneurial family has maintained and serviced its technology with the utmost care, like items of jewellery. It is for this reason that the site is now home to a number of functional treasures of historic value. It is necessary to note here that the impression that the technology is somewhat «older» only applies occasionally, because the equipment is regularly modernised and thereby aligned with the latest engineering practice. The dry excavation works are performed by a chain excavator of type O & K RH6 and a Hanomag 44 D wheel loader with weighing mechanism, which also takes care of the loading.
For the purpose of efficient wet excavation, the first cable dredgers — a legendary Weserhütte W3 and a «Pioneer» W2 with 11 or 7 t operating load — were acquired at the start of the 1950s. The W3 in its original livery remained in regular use in the gravel pit until 1970. Thanks to good maintenance and care, it remains functional to this day and available for smaller tasks where required after minor preparations.
For the main, wet excavation has primarily taken place using Stichweh drag scrapers since 1961. This was initially performed by a KS 100, mounted on rails, and subsequently by a KS 124. From the end of 2014 it is intended that a generally overhauled Stichweh KS-200 drag scraper with electric drives and frequency control carry out the dredging work. The raw material is prepared with a 1 1/2 deck Stichweh screening machine, as well as a double-deck screen from Siebtechnik GmbH. The screens are equipped with Steinhaus PUR screen linings and products from Meister. Gravel and sand grain sizes of 0/16, 0/32 and 16/32 mm are produced, as well as natural sand 0/2-0/3 (aggregate 0/2 b according to DIN 4226). The preparation works also attest to the long-term thinking of the grain producer when it comes to the equipment used: A number of the discharge conveyors still originate from 1952 and 1967. As previously mentioned, all devices and machines are regularly serviced and refuelled in a large, covered hall.
Conflict between expansion and water protection
In 1982, a designated water conservation area defined in the districts of St. Sebastian, Koblenz-Bubenheim and Koblenz-Kesselheim brought with it significant limitations for the continuation of the company. At that time, the gravel excavation — ongoing since 1910 — fell within the water conservation zone III A, for which only dry excavation was permissible in the future. The excavation of the groundwater surface approved in 1962 remained permissible to the extent agreed at that time, although an expansion would only be conditionally possible through dry excavation. Various attempts to apply for an expanded area failed due to the size of the designated water conservation area. Furthermore, areas that had not yet been quarried bordered the water conservation zone II and had also flourished such that they were of high value from a nature conservation perspective. The mid and long-term continuation of the company under Christoph Leimig — the third generation proprietor — therefore appeared to be seriously at risk by the end of 2000. Following intensive discussions with ministries, as well as the approvals and regulatory authorities, a parcel exchange was assessed on the basis of the framework conditions, because the clogged and well-established north-eastern slope of the approved quarry was to be retained for reasons of water protection and nature conservation. From a hydrogeological perspective, the only exchange parcel feasible within the scope of the approved extraction site consisted of the slopes to the south of the gravel pit. Following lengthy negotiations, at the end of 2003 the company was able to acquire the plots neighbouring the gravel pit to south, meaning that a parcel exchange would be fundamentally possible. In 2006, the company formally renounced the approved excavation areas directly adjacent to the water conservation zone II. In return, the approval was issued for excavation of the exchange parcels to the south-east of the pit. Following the exchange, the scope of excavation approved in 1962 remained the same with respect to the area and excavated quantity. However, the distance from the zone was increased with a higher protection status.
Given its history, it is entirely clear that the company was only able to remain in existence because the entrepreneurial family had always acted with the deepest conviction in protecting the groundwater. Anyone who — like the Leimigs — has safeguarded the private drinking water supply from a well on the northern boundary of the gravel pit since 1956, and even before that obtained drinking water from a domestic well, simply has water conservation close to their heart. Since June 2012, the gravel lake has also served to heat the family’s home. A 900 m long probe was laid in the water body for geothermal energy generation. Drinking water, without the addition of coolant, is used as the exclusive carrier fluid — which is self-evident given the special location within the water conservation zone III A. However, the numbers still add up: A heat exchanger with a 45 kW rating draws sufficient heat from the lake water for the 15 kW heating system. In July last year, the project «geothermal energy acquisition from a quarry lake» was even awarded an environmental prize by the district of Mayen-Koblenz.
Careful treatment of nature has enjoyed a lengthy tradition with Leimig, far beyond drinking water protection alone. «The Leimigs are known for creating no problems», emphasizes present proprietor Christoph Leimig, highlighting the attractive refuge on the doorstep. This is made up of an artificial lake within a regional green corridor, the banks of which offer protection to birds and insects. With its patchwork structure — consisting of pioneer habitats, steep walls of loam and moulded sand, the expanse of water, surrounding hedgerows and in particular the old wooded groves on the edges of the pit — the excavation site constitutes a richly structured ecosystem. The foundations for this were laid by the father of the present proprietor over 50 active years. He rejected any form of backfilling, even when it would still have been possible, and was responsible for extensive planting on the slopes. The undisturbed areas, in which protected plant communities and numerous red list species are found, are of great significance as a retreat area for flora and fauna in an otherwise cleared and intensively worked landscape. The fish population in the lake is able to develop undisturbed, because fishing and other recreational uses do not take place here. The area can be essentially sure of being designated a nature conservation area.
However, for the time being the operator wishes to continue demonstrating that nature conservation and raw materials extraction can be combined with each other, and intends to safeguard future expansion of the gravel production. Through a redefinition of the water conservation zones it is likely that new extraction areas can be developed directly adjacent to the approved areas. However, a prerequisite for this is the hydraulic separation of the expansion area from the present extraction area. The expansion area is bordered by existing connecting routes and by the intersection of the BAB 48 with the B 9 national road. As such, the expansion area would have a relatively minor impact, although gravel quarrying would also be secured for the fourth generation because the company only produces in small volumes and only operates on its own land with its own equipment. This enables cost-efficient production and cost-efficient shipping, due to predominantly local distribution. With Jan Gundlach, the nephew of the present company proprietor, the fourth generation of the Leimig family is already preparing to continue with the company management. Jan too knows the responsibility that comes with this heritage: The survival of a small company like this is dependent on the intensive commitment of the entire family, as well as the exceptionally precautionary approach that has been adopted for many years now.
Publication authorized by Stein-Verlag GmbH, Iffezheim.
Original issue published in GP GesteinsPerspektiven 4/2014; authors: Leimig/Breitkreuz/Schulz (gsz)