Mid-Congress Excursions

Field Trip 1 – Dewatering in Liège: Dealing with hydraulic consequences of coal mining and flood events

Field Trip 2 – Valorisation of dewatering groundwater abstracted from large limestone quarries (Soignies)

Field Trip 3 – Quartier Bleu Hasselt – Shopping and living on green energy in the heart of Hasselt

Field Trip 4 – Wastewater recycling and managed aquifer recharge (MAR) at the Belgian coastal area

Field Trip 5 – Modave – The biggest groundwater catchment in Belgium and a beautiful castle

Field Trip 6 – Spa – Groundwater from the heart of nature

Field Trip 7 – The HADES underground research laboratory (EIG EURIDICE), the hydrogeological research at SCK CEN, and the Balmatt deep geothermal power plant (VITO)

Field Trip 8 – Rochefort area and its Devonian limestone fractured and karstic aquifers

Field Trip 9 – Stone, Chemistry, and Groundwater: a Walloon story

Field Trip 10 – Dewatering and geothermal exploitation in the Mons sedimentary Basin

Field Trip 11 – Management of nitrate and pesticides vulnerability in karstic groundwaters

Field Trip 1 – Dewatering in Liège: Dealing with hydraulic consequences of coal mining and flood events

Coal mining was an important economic activity in Belgium in the XIXth and XXth centuries, as the last coal mines only closing in the early 90’s. Due to the extraction of coal, subsidence and subsequent collapses occurred as well as an increase in fracturation degree and, consequently, bedrock permeability.

In the Liège Coal Basin, subsidence varying from 1 to 6 m was observed in the river plain. As a consequence, topsoils lowered below the Meuse river level, leading to dramatic floodings in the river plain during the winter 1925-1926. However, overflow floodings was not the only post-mining issue that appeared.

Today, it is known that groundwater rebound starts as soon as the extensive pumping operations required for the mining activities stops but continues until the mine water surface equilibrates with the regional groundwater level or reaches a point of discharge, e.g. a drainage adit. Consequently, pressure and stress redistribution occur in the underground which can induce outbreak, flooding and/or stability problems in the surrounding area.

More than forty years after mine closure in Liège, the public company AIDE still manages dewatering systems to reduce flooding risks. In the meantime, the public company ISSeP is in charge of flow rate and water level monitoring in the mines to early detect potential outbreaks since these occurs when an increase in hydraulic heads is observed without inducing a discharge increase downflow.

During this field trip, post-mining management systems will be presented in the iconic “Pumping Station n°6” of AIDE. To have a better idea of the geology and mine geometry of the Liège coal basin, the abandoned coal mine “Blégny-mine”, listed as UNESCO World Heritage Sites since July 2012, will then be visited.

Programme

  • Arrival at the “Pumping Station n°6” in Seraing
  • Presentation of the post-mining management issues in the Coal Basin of Liège (ISSeP)
  • Presentation of the dewatering project in Liège and visit of the pumping station (AIDE)
  • Visit of Blégny-Mine

Maximum # of participants: 50

Flooding of 1925-1926 in Seraing

Example of AIDE dewatering facilities

Field Trip 2 – Valorisation of dewatering groundwater abstracted from large limestone quarries (Soignies)

The extraction of rocks below the groundwater level often requires dewatering of large quantities of groundwater. This visit aims to show how groundwater abstracted in open pit quarries for dewatering purposes can be valorised and used for drinking water supply, thanks to a fruitful collaboration between quarry operators and water producers. Valorisation of dewatering groundwater is more and more performed in Belgium. In the country, dewatering operations represent about 30 million m³ of groundwater abstracted each year.

Located 40 km south of Brussels, the visited sites concern dewatering operations in the « Carrières du Hainaut » (stone quarry) located in the city of Soignies, and valorisation of the abstracted groundwater thanks to a water treatment plant.

The « Carrières du Hainaut » (Quarries of Hainaut) will be visited. This stone quarry extracts limestone of Carboniferous age, to be used as ornamental rock or as aggregates. Stone extraction will be visible in the open pit. Groundwater inflows in the quarry through open fractures and weathered limestone areas. This groundwater is collected, thanks to special arrangements which have been implemented in the open pit. Abstracted groundwater volumes correspond to dewatering flow rates of 400 m³/h.

Dewatering groundwater is conveyed from the stone quarry to a treatment plant which ensures drinking water standards. The Ecaussinnes plant will be visited. It is setup for the treatment of maximum 1000 m³ / h of water coming of various stone quarries in the region.

Short stops are planned at old and new boat lifts, which connect several canal sections located at different elevations. The largest boat lift (Strépy-Thieu) connects two canal sections separated by a vertical drop of 73 m in 6 minutes.

After the technical visits, a visit of the ‘Brasserie Saint-Feuillien’ is planned. The brewery is located about 10 km from the visited quarry and treatment plant. This third visit will allow seeing the fabrication of abbey beers … with water abstracted from the same limestone aquifer observed in the open pit quarry during the morning. We can also taste any beers…

Water inflows into the open pit quarry

Dewatering water treatment plant

Boat lift in Strépy-Thieu

Field Trip 3 – Quartier Bleu Hasselt – Shopping and living on green energy in the heart of Hasselt

Hasselt is the largest city of the Flemish province of Limburg. Best estimates indicate that the city was founded in the 7th century and has a known rich history. Today a number of historical buildings are open to the public, like the St. Quentin’s Cathedral (11th to 18th centuries).

More recently, Hasselt was the first city to receive the title of the “most sociable city of the region of Flanders”, and has also claimed the title of “Capital City of Taste”. Amongst others it is know for its “Jenever” or Dutch gin.

Quartier Bleu is an entirely new residential area located at the ‘Hasseltse Vaartkom’, with a focus on living, shopping and dining. The “small village within the city” consist of 400 residences divided over 8 blocks, a shopping mall of around 22.000 m² (or 35 stores) and 3.000 m² of eateries.

Sustainability has been a crucial aspect within the development of Quartier Bleu, resulting in a geothermal heating and cooling system, which was entirely designed, constructed and installed by a local company IFtech (iftech.be).

The underground system consists of six wells, each 213 m deep, which can pump up to about 225 m³ of groundwater. The technical area is equipped with two enormous heat exchangers. The entire installation can generate up to 2,6 MW that is distributed over a local energy grid spanning the residential area. Each living and trade unit has its own geothermal heat pump, allowing autonomous heating of the spaces during the winter months and cooling during summer. This clean and green installation is estimated to reduce 747 tons of CO2 per year.

You will visit the technical chamber under guidance of one of IFtech’s engineers, followed by a tour of the residential area with a visit of the pumping wells.

More information:

www.iftech.be

https://www.groepvanroey.be/nl/referentieprojecten/quartier-bleu

 The province of Limburg has also a long history of coal mines, and the tour will include a visit of the Beringen Colliery.

Programme

  • Arrival at Quartier bleu
  • Visit to the Quartier Bleu
  • Walking tour of the city center passing by the Sint-Quintens Cathedral and by the new town hall Hasselt city hall – sustainable heating and cooling of the city hall. In 2018, the city of Hasselt built a new city hall, again with of focus on sustainability. IFTech provided the geothermal heating and cooling installation consisting of 2 wells with a heating capacity of 650 kW and cooling capacity of 600 kW. The installation is estimated to save up to 120 ton of CO2 per year.
  • lunch at Quartier Bleu or in the Hasselt city center
  • Visit of the Beringen Colliery The Beringen colliery – back to the past. At the foot of two slag heaps the colliery in Beringen is considered to be Flanders’ best-preserved and largest industrial heritage site. During a 2-hour guided tour, usually narrated by an ex-mining employee, we will explore the historic mining buildings and get a better understanding of the working conditions, linked to a short geological history of Belgium. The field trip will end with a short presentation of one of AGT’s groundwater models that addresses issues with the water household related to the subsidence caused by the mining activity.More information:https://www.visitlimburg.be/en/beringen-colliery

Maximum # of participants: 50

Field Trip 4 – Wastewater recycling and managed aquifer recharge (MAR) at the Belgian coastal area

At the Belgian coastal plain, saltwater is present at the sea and in the low lying polders while freshwater lenses are present in the dunes and are exploited for drinking water production.

Water extraction can induce saltwater intrusion from both the sea and polders side. To counterbalance this phenomenon, the water company IWVA is using treated wastewater from the sewage system for managed aquifer recharge (MAR) at his production site of Sint-André since 2002. In 2019 the volume of infiltrated water represented 65% of the water production at St-André. The infiltration is achieved with infiltration ponds and since 2014 also through underground infiltration boxes. For the extraction of the infiltrated water IWVA operates about 200 siphon wells. The managed aquifer recharge system has been successful in restoring sustainable groundwater management enhancing natural values of the dune area and preventing saltwater intrusion on the long term.

This part of Belgium is also well known as “Flanders Fields”, where dramatic battles occurred during World War I. This visit will be the opportunity to pay tribute to the victims of all camps.

Programme

  • Arrival at Torreele, at the wastewater treatment plan.
  • Presentation of the geology and hydrogeology of the Belgian coastal area and problematic of saltwater intrusion (by UGent)
  • Visit of the wastewater treatment facilities of Torreele
  • Presentation of the managed artificial recharge project
  • Lunch in Torreele
  • Visit of the infiltration and extraction facilities of Sint-André
  • Visit of the nature reserve de Doornpanne.
  • Visit of the cemetery World War I German military cemetery of Vladslo (Dixmude)

Maximum # of participants: 100

Infiltration point in the dunes

Conceptual model of groundwater flow and saltwater intrusion risk at Sint-André

Field Trip 5 – Modave – The biggest groundwater catchment in Belgium and a beautiful castle

Modave is located in the Condroz region, which is characterized by a typical succession of limestone synclines (valleys) and sandstone anticlines (ridges). The fractured and karstified carboniferous limestones present in the Condroz region are an extremely important drinking water resource for Belgium and its various regions (especially Wallonia and Brussels).

VIVAQUA, the Brussels water company, operates in Modave the largest groundwater catchment in Belgium in terms of volume captured (up to 80,000 m³/d). The diversion of the springs of the Hoyoux River with 5 km-long draining galleries began 100 years ago. Today, groundwater collected in the drainage galleries still flows naturally (by gravity) into a 90 km-long water collector towards Brussels.

VIVAQUA also owns the Modave castle (http://www.modave-castle.be/infos_pratiques/langue_en), built during the middle age and situated on a cliff 60 m above the Hoyoux River. In order to irrigate the gardens of the castle, a hydraulic wheel was built in the 17th century. It was this wheel that inspired the one built at Versailles.

After visiting the draining galleries of the Modave catchment site, participants will have the time for a walk along the Hoyoux River and the cliff where the Modave castle is built. The tour will follow its journey with hydrogeophysical demonstrations on how to identify, image, characterize, and monitor preferential groundwater flow in fractured and karstified limestone. Participants will hear about electrical resistivity tomography and streaming potentials methods, among others.

Participants will then follow the small path that starts from the Hoyoux valley and winds its way up the hill to reach the Modave castle. There, a typical Belgian lunch will be served. After a moment of relaxation in the park of the castle, the participants will be able to visit it and hear more about the castle and the hydraulic wheel.

Programme

  • Presentation of the site and of the (hydro) geological context will be given in the bus.
  • Arrival in Modave
  • Visit of the VIVAQUA groundwater catchment site and walk along the river Hoyoux
  • Visit of the Castle of Modave

Maximum # of participants: 50

Draining Galleries

Geophysical demonstrations

Modave Castle

Field Trip 6 – Spa – Groundwater from the heart of nature

The Spa Waters is the result of remarkable mineral springs long considered as miraculous. Since the sixteenth century, notable guests from all over Europe started to stay in Spa to enjoy the benefits of drinking mineral waters possibly associated to hydrotherapy treatments. So when speaking about mineral waters and balneotherapy, it has become usual to simply name it a ‘spa’. Indeed, in the area of Spa (eastern Belgium), many springs of mineral waters are observed that can be both naturally sparkling and rich in iron.

Mineral groundwaters of Spa infiltrate in a very specific environment, where we will start our daytrip: the High Fens (‘Hautes Fagnes’), a high plateau (lately influenced by the last ice age) consisting mainly in raised bogs, and low, grass- or wood-covered hills, moorland and forest. Beautiful landscapes and a bustling biodiversity are waiting for you and the area is thus protected in by a Natural Parc status. These peaty highlands act as a natural sponge for water infiltration. We will visit the fens by foot so we can get the chance to enjoy a beautiful point of view from a panoramic tower.

After visiting (and tasting !) a natural spring of naturally CO2-rich groundwater, we will be ready for a healthy lunch in a super nice place in the middle of the Spa forest.

Our tour will then continue to follow the journey of groundwater as we will visit ‘Spa Monopole’, a bottling plant established in the city more than 100 years ago where we will talk about today’s technologies and tomorrow’s challenges regarding mineral water.

We will not miss the chance to have a glimpse of the very nice and touristy historic center of the city of Spa which is candidate to a UNESCO recognition, where we will visit the ancient thermal establishment that has been freshly renovated.

Programme

  • Arrival in Spa, at the Domain of Bérinzenne
  • Meeting in the “Pavillon Lilien”. Presentation of the site, the geological context, the natural park & LIFE project
  • Walk to the Berinzenne panoramic tower to see the fantastic scenery point of view on the whole area
  • Lunch at the Barisart Restaurant and tasting of the groundwater from the spring
  • Visit of the Spa Monopole bottling plant
  • Visit of the “Eaudyssée” in the Spa Monopole plant, view on the bottling lines and explanation about the environmental commitments
  • Glimpse of the historic city center, the “Parc des 7 heures”, and the renovated old thermal establishment

Maximum # of participants: 35

Berinzenne

Pouhon Géronstère

Fagnes

Field Trip 7 – The HADES underground research laboratory (EIG EURIDICE), the hydrogeological research at SCK CEN, and
the Balmatt deep geothermal power plant (VITO)

During the field trip, you will spend half a day at EIG EURIDICE, where you will visit the exhibition on geological disposal of radioactive waste in a deep clay formation, and the HADES underground research laboratory. The other half day, you will visit the deep geothermal power plant (Balmatt, VITO), and get an overview of the hydrogeological research at SCK CEN, the Belgian Nuclear Research Centre.

The HADES underground research laboratory, located in the Boom Clay at a depth of 225 meters, plays a central role in research into the safety and feasibility of geological disposal of radioactive waste. Experts use it to develop and test industrial technologies for building, operating and closing a waste repository in deep clay. Scientists conduct large-scale experiments under realistic conditions in the deep clay formation over a long period of time to assess the safety of geological disposal in poorly indurated clay.
Renowned worldwide, HADES is the oldest underground laboratory in Europe built in a deep clay formation, for the purpose of researching the possibility of geological disposal in clay. The International Atomic Energy Agency (IAEA) recognizes it as a center of excellence for waste disposal technologies and scientific training. HADES is a licensed nuclear research facility, which means that scientists can use a wide range of radioactive tracers and sources.

SCK CEN began the construction of HADES in 1980. Since 1995 HADES has been operated by the Economic Interest Grouping EIG EURIDICE, a partnership between SCK CEN and the Belgian Agency for Radioactive Waste and Enriched Fissile Materials (ONDRAF/NIRAS). In Belgium, ONDRAF/NIRAS is responsible for radioactive waste management and coordinates the geological disposal RD&D programme.

HADES is and will continue to be purely a research laboratory. It will never be extended for use as a repository for radioactive waste. In any case, the shafts and galleries would be too small, and the clay has been disturbed as a result of the many experiments carried out. When construction work gets under way on a real repository, HADES can, however, continue to serve a useful function as a research facility, where specific techniques can be pre-tested or fine-tuned, if necessary.

VITO, the Flemish institute for technological research, started drilling in 2015 for the deep geothermal Balmatt project, located on a brownfield site in Mol (Belgium). In a first well, the top of the Lower Carboniferous Carbonate reservoir was reached at 3.174 m depth. Increased transmissivity was found along a fault. A second injection well was installed in March 2016, and deviated from the vertical, in order to keep enough distance from the first well in the reservoir. In December 2017, a third well was drilled, targeting the same faulted zone as the first well. This 4.235 m deep well reached the Devonian strata.

This pilot installation allows VITO to investigate various topics related to the use of deep geothermal energy, besides the obvious geological and energy production-related expertise:
• Corrosion and scaling: The geothermal water has a high salinity (165 g/l). The combination with high temperature and high-pressure results in an aggressive fluid for both dissolution of metals and precipitation of minerals in the casing and surface installation. VITO tests the use of different materials.
• NORM (Natural Occurring Radioactive Materials): These elements are the result of the decay of natural U and Th which are found everywhere in the Earth’s crust. As the geothermal water is reinjected, most of these elements go back into the reservoir. Samples are taken periodically from the filter elements, scalings and the geothermal water in order to determine the activity level.
• Microseismicity: The reinjection of cooled water into the deep reservoir can cause small artificially induced earthquakes. To monitor this microseismicity VITO has developed a dense seismometer network, which allows to locate the events by tens of meters accuracy. By monitoring the injection pressure and temperature, VITO guarantees the safe operation of the plant.

The evolution of hydrogeological research at SCK CEN is closely linked to R&D developments in the long-term management and storage of radioactive waste. Already more than 30 years ago, the first hydrogeological models were developed, in the framework of geological disposal of high-level and long-lived radioactive waste. Initially, these catchment-scale models were rather simple and fit for purpose but gradually gained more complexity. Meanwhile, detailed local models were being developed, in the framework of the near-surface disposal facility for low-level and short-lived waste.

Building upon the tradition of head-calibrated hydrogeological models, subsurface hydrological research at SCK CEN is moving forward by gradually incorporating alternative state variables such as heat and radioactive isotopes. A lot of effort is also being put in river-aquifer and saturated-unsaturated zone coupled modelling. This expertise is now enlarged in a series of non-waste related projects where, amongst others, the past and future hydrology of alluvial plains and recharge areas is being assessed. Finally, SCK CEN is also involved in cross-border projects aiming at the harmonisation of subsurface hydrological information (B/NL/D).

Programme

  • Arrival at EIG EURIDICE
  • Welcome and introduction
  • Visit of HADES
  • Guided tour of the exhibition
  • Lunch
  • Arrival at Balmatt site
  • Presentation & visit of the deep geothermal power plant
  • Arrival at Lakehouse
  • Presentation by SCK CEN

Maximum # of participants: 68

HADES laboratory

HADES laboratory

Balmatt site

Field Trip 8 – Rochefort area and its Devonian limestone fractured and karstic aquifers

Rochefort is located in the Unesco Global Geopark “Famenne – Ardenne”. The regional landscape and topography are strongly influenced by the geology due to the succession of various Devonian geological formations consisting of shales, fractured or karstified limestones and sandstones.

The field trip will be focused on two sites : the Lorette cave and the Boverie Quarry.

The Lorette cave is part of the Lomme karst system that has an extension of more than 15 km of development in the Givetian limestone. The cave hosts a unique underground laboratory focused on hydro-geophysics. A recent scientific project, initiated in 2013 and called “Karst Aquifer ReseArch by Geophysics” (http://karag.be/en/), aims at leveraging the team research experiences in karst, hydrogeology, gravimetry and geophysics (ERT) to understand the water dynamics and storage in the unsaturated and epikarst zones which are the lesser known part in the karst water balance and dynamics. The project partners will present the 8 years of multidisciplinary investigations of karst water dynamic.

The Boverie Quarry located in Frasnian limestone reefs is operated by Lhoist  (https://www.lhoist.com/be_en) to produce high-quality lime. The limited extension of the reefs, surrounded by shale deposits, creates an isolated aquifer that outcrops over an area of 1.8 km². As this aquifer is of strategic importance for the water supply of the Rochefort city and the Rochefort Abbey, it has been studied and monitored since 2008 in order to manage this groundwater resource in a sustainable way while considering the deepening of the existing quarry. Interesting results that concern the aquifer dynamic during gravity flows or pumping periods (as water table fluctuations, quarry pit influence on recharge, surface water infiltration or drainage …) will be presented.

Programme

  • Arrival in Rochefort (Lorette Cave touristic centre)
  • General introduction to the regional geology (conference room of Lorette)
  • Visit of the Boverie Quarry (Lhoist Group)
  • Lunch
  • Visit of the Lorette Cave and its underground laboratory

Maximum # of participants: 50

Field Trip 9 – Stone, Chemistry, and Groundwater: a Walloon story

This field trip will focus on a theme dear to Wallonia: the sustainable exploitation of rock and groundwater as well as the remediation of historical contamination related to rock mining and processing for the chemical industry. This field trip will focus on the Dinant Synclinorium geological structure composed of a succession of fractured and karstified carboniferous limestone synclines and sandstone anticlines. Participants will be in the areas of Couillet, Charleroi (60 km south of Brussels) and Florennes (20 km south of Charleroi and 80 km south of Brussels).

The Belgian chemist Ernest Solvay invented the Solvay process at the end of the 19th century for the production of soda ash (Na2CO3) from salt (NaCl) and limestone (CaCO3). The co-product of soda ash manufacture is calcium chloride (CaCl2), which has historically been deposited in settling ponds. One example is in Couillet, Charleroi where Ernest Solvay opened his first factory at the end of the 19th century. As the calcium chloride deposits leached out, the chlorides slowly migrated to the aquifer and later, to drinking water catchments in the area. The first part of this field trip will be devoted to the hydrogeological field studies and the measures implemented to confine the contamination at its source and then to clean up the impacted carboniferous limestone aquifer. The visit will focus on the rehabilitated settling ponds and the quarry that Solvay used to operate for soda ash production and which is now used as a containment point.

Limestone is a highly available raw material in Wallonia and its exploitation is still ongoing. Today, water producers, the extractive and chemical industries, the public administrations that are concerned, and hydrogeological consultancies are working hand in hand to exploit water and stone resources sustainably. The second part of this field trip will be devoted to this topic through the prism of the Hemptinne Syncline workgroup. The afternoon will thus focus on the characterisation and modelling of groundwater flow in the Hemptinne limestone syncline and on field demonstrations. Participants will have the chance to visit one the quarry inside this syncline and see how all actors managed to valorise dewatering water for local drinking water supply.

Programme

  • Presentation of the geological and hydrogeological contexts in the bus, by AQUALE
  • Arrival in Couillet, Charleroi, and visit of the rehabilitated settling ponds of Solvay (historical source of the chloride contamination)
  • Visit of the Fiestaux Quarry owned by Solvay, which is now the containment point of the chloride contamination
  • Transfer to the Hemptinne limestone syncline and visit of the Calcaires de Florennes quarry
  • Presentation of the Hemptinne workgroup and visit of the pumping station that valorises dewatering groundwater
  • Field demonstrations

Maximum # of participants: 50

Rehabilitated settling ponds in Couillet, Charleroi

Containment point of the chloride source in the Fiestaux Quarry (Couillet, Charleroi)

Calcaires de Florennes Quarry

Pumping station for the valorisation of dewatering water in the Calcaires de Florennes Quarry

3D groundwater flow model of the Hemptinne syncline developed by AQUALE

Field Trip 10 – Dewatering and geothermal exploitation in the Mons sedimentary Basin

The Mons city area located about 50 km South-West of Brussels has long history linking industrial developments and geology. It includes past coal mining, phosphatic chalk exploitation, chalk extraction for cement production, geothermal exploitation, groundwater abstraction for drinking water supply, groundwater dewatering in relation to subsidence induced by pas mining operations.
This visit aims to show some of this history, in relation with geothermal exploitation and dewatering operations in the Mons city area. During this field trip, we will visit the geothermal station of Saint-Ghislain and a groundwater pumping site consisting of a draining gallery connected to the flooded underground quarries of La Malogne.

The Saint-Ghislain borehole and geothermal station are located about 9 km West of Mons city. The South-West of Belgium, the Hainaut limestone geothermal reservoir is exploited since the eighties. The geothermal reservoir is mainly composed of limestone from the Carboniferous period, with highly permeable breccia evaporites levels. Saint-Ghislain borehole was the first location in Belgium where geothermal energy started to be exploited. It was drilled between 1972 and 1976 for geological research purpose. This single well currently extract warm groundwater from the transmissive breccia layers located around 2000 meters deep and provide energy for the heat production to two hospitals, schools, station, housings and an economic area. The pumping groundwater temperature is about 70°C.

The La Malogne underground quarry is located in the central part of the Mons Basin. The excavating galleries spread over kilometres in the Maastrichtian phosphatic chalk, which has been actively mined between the 19th to mid-20th century, mainly for feeding the fertilizer industry. Today, extracting operations in the quarries have stopped and the galleries are partly flooded. A groundwater abstraction station, located just beside the quarry, is closely related to this site. The station consists in a vertical shaft and a 200m-long draining gallery. The draining gallery is connected to the flooded quarry with a system made of multiple drains.

Programme

  • Arrival at the Saint-Ghislain Pumping Station
  • Explanations and visit
  • Lunch
  • Visit of the La Malogne quarry (to be confirmed) or the catchment of La Scierie
  • And a local touristic surprise …

View of the underground quarry of La Malogne where galleries are flooded

Saint-Ghislain geothermal station

Field Trip 11 – Management of nitrate and pesticides vulnerability in karstic groundwaters

The aim of this field trip is to show the management of the vulnerability of karstic groundwater in two projects :

  1. Bioindicators as an early warning of groundwater pesticides vulnerability in a small rural basin of Southern Belgium
    This field trip will illustrate an ongoing study that takes place in the Néblon basin (limestones aquifer). This groundwater body is in good chemical status, with an upward pollution trend for pesticides. Underground and surface karst phenomena take place at numerous sites within the basin. Several swallow holes are well known. They play a major role in terms of groundwater vulnerability.
    The study has been using honey bee, earthworms and aquatic vegetation as bioindicators to assess the quality of the air, soil and water ecosystems. In parallel, samples have been collected in air, soil and groundwater in search for pesticides content during 2 sampling campaigns, summer and autumn 2020. Herbicides are at major concerns in the first results.
    The field trip includes a visit of the “Néblon galeries” of the CILE (the Liège water company). This drinking water catchment, carried out in the first part of the twentieth century, consists of six galleries dug on 600 meters not far from the Néblon river.
  2. EPUKarst – fluctuation in nitrate concentration within karstic groundwaters – case study of the “Vallon des Chantoirs” (Province of Liège, Belgium)
    The EpuKarst ongoing study compares nitrate contents in groundwaters of 5 different karstic systems distributed over southern Belgium. The chosen systems allow to measure (every two months over a period of 2 years) nitrate concentrations, not only in swallow holes (income points in karst) and karstic springs (groundwater resurgences), but also within the karstic systems themselves (in saturated, unsaturated and trickle waters) thanks to the involvement of cavers.
    The fieldtrip will take place in the “Vallon des Chantoirs”. This narrow strip of Devonian limestone reaching the Amblève river, drains all surface waters towards a subterranean collector through 17 swallow holes. The visit includes the most impressive of those infiltration sites, as well as the Remouchamps (touristic) cave, outcome of this entire karstic basin.
    The first results concerning nitrate seasonal fluctuations, site variability, possible attenuation linked to groundwater residence time, as well as the sampling protocols and methods will be discussed during the trip.

Programme

  • Presentation of the site and of the (hydro) geological context in the bus
  • Arrival in the Néblon basin
  • Visit of Remouchamps

Maximum # of participants: 50

Remouchamps Cave

A Bee as indicator (by Gilles San Martin)

Béron Ry