Abstract: The ecology of the River Pelenna (in South Wales) was impoverished by polluted discharges from abandoned coal mines. A series of passive constructed wetlands was created in order to treat these discharges and to improve the ecology of the river. A three-year Environment Agency R&D project investigated the performance, environmental benefits and sustainability of the constructed wetlands. It showed that the treatment systems were removing most of the iron contamination. In the reaches downstream from the minewaters, the dissolved-iron concentration quickly dropped below the target level. Invertebrate abundance, trout and riverine bird populations increased in following years. However, occasional overflows from the systems have significantly affected the ecology of one stretch of river The research work has provided an insight into the potential for ecological recovery associated with future minewater treatment.

Abstract: Vor dem Hintergrund einer planmäßigen Tagebauentwicklung muss der das Gewinnungsfeld in Nord-Süd-Richtung durchquerende Fluss Inde Ende 2005 bergbaulich in Anspruch genommen werden. Als Ersatz wurde auf Grundlage des Planfeststellungsbeschlusses vom 10.09.1998 eine neue Inde auf einer Länge von rd. 12 km erstellt. Rund 10 km der neuen Inde liegt innerhalb des Tagebaufeldes. Hierzu musste eine Flusslandschaft angelegt werden. Im Gegensatz bisher anthropogen geprägten Inde, ist eine naturnahe und weiträumige Flusslandschaft vorgesehen. Die Gestaltung soll, in Verbindung mit den zahlreichen eingebrachten Landschaftselementen wie Flutmulden, Altarmansätzen und Kolke, eine artenreiche und ökologisch hochwertige Auenlandschaft ermöglichen. Die Flutung der neuen Inde erfolgt auf Grundlage eines dreiphasigen Gewässerumschlusskonzeptes. Im Anschluss an die Flutung soll ein Monitoring- Programm zur Dokumentation der hydrodynamischen, morphologischen und landschaftsökologischen Entwicklung der Indeflur durchgeführt werden. Against the background of the scheduled eastward development of the Inden opencast mine, the Inde river which runs there must make way for mining operations at the end of 2005. Prior to this, as a replacement for the riverbed, which is some 4.5 km long, a riverscape has had to be created as a bypass in the west, mainly within the scope of rehabilitation measures. The model built for this purpose based on historical records provides for a close-to-nature and spacious riverscape with hand- and soft-wood meadows, unlike the anthropogenically marked Inde of today, with a meandering mean water bed. This design, in conjunction with the many installed landscape elements, like flood hollows, creeks and potholes, aims at creating a diverse and ecologically high-quality meadow landscape. The main factors impacting the river's route were the opencast mine's geometry and progress, as well as the planned and existing utilization of the land surfaces outside the opencast field. Besides these constraints, there were stipulated vertical points due to hydraulic requirements. The Inde plains, taking account of the planned route, were created on the basis of a design template, which provides for a stable level, a sealing layer and a cultivatable meadow substrate layer. In addition, the meadow substrate layer protects the sealing layer from erosion thanks to its medium- and coarse-grained gravel content. The Inde was constructed in the opencast field within the scope of rehabilitation in spreader operations, meaning that it was possible to dump the material to be installed in line with the design template and given elevations. The flooding of the 'new' Inde was based on a three-phase waterway rerouting concept and provided for increasing discharge quantities. This enabled a bottom covering layer to be formed successively, and ailowed the aquatic fauna to gently adapt to the changed living conditions and further seed material to be flushed in.

Abstract: The wastewaters coming from mining operations usually have low pH (acidic) values and high levels of metal pollutants depending on the type of metals being extracted. If unchecked, the acidity and metals will have an impact on the surface water. The organisms and plants can adversely be affected and this renders both surface and underground water unsuitable for use by the communities. The installation of a treatment plant that can handle the wastewaters so that pH and levels of pollutants are reduced to acceptable levels provides a solution to the prevention of polluting surface and underground waters and damage to ecosystems both in water and surrounding soils. The samples were collected at five points and analyzed for acidity, total suspended solids, and metals. It was found that the pH fluctuated between pH 2 when neutralization was forgotten and pH 11 when neutralization took place. The levels of metals that could cause impacts to the water ecosystem were found to be high when the pH was low. High levels of metals interfere with multiplication of microorganisms, which help in the natural purification of water in stream and river bodies. The fish and hyacinth placed in water at the two extremes of pH 2 and pH 11 could not survive indicating that wastewaters from mining areas should be adequately treated and neutralized to pH range 6-9 if life in natural waters is to be sustained. < copyright > 2005 Elsevier Ltd. All rights reserved.