Gravenhorst mine water treatment plant (AzGA)

The plant was constructed in several stages:

1. Preparatory measures
   - Sheet pile sealing wall constructed and maintained until the end of the construction project. 3,700 m² of steel sheet piling in lengths between 14.0 and 15.0 metres was installed as a temporary sealing wall.
   - Construction of a sheet piling box using the CSM (Cutter-Soil-Mix) method. The soil was excavated underwater, after which 950 m³ of underwater concrete was placed as the base of the excavation pit.
    
2. Construction dewatering
   - Closed dewatering with vertical filter wells, combined with vacuum filter lances including water treatment for transfer to the tunnel stream; geodetic head up to 6.0 metres.
    
3. Civil engineering, engineering and traffic facilities
   - Neutralisation basin facility with a basin volume of up to 3,600 m³.
    
4. Traffic facilities in asphalt construction including drainage and lighting
    
5. Mechanical and process engineering including pipeline construction and steel construction for
   - Feed
   - Neutralisation / sedimentation / post-sedimentation
   - Demangling / final pH adjustment
   - Dewatering
   - Control air supply / drinking and process water supply
   - Exhaust air technology and unloading area for chemicals
    
6. Electrical and process control technology
   - Ensuring the security of supply of the existing plant
   - Utilisation and expansion of the existing infrastructure
   - Medium-voltage supply / central main energy management / decentralised low-voltage supply
    
7. Automation and process control technology focussing on
   - Social building
   - Sludge treatment
   - Chemical treatment
   - Lime milk treatment
   - Communication technology