Study of Capillary Channel Fiber Augmented Geobags for Accelerated Dewatering of High Moisture Content Fine-Grained Acid Mine Drainage Precipitate

The objective of this study was to investigate techniques to accelerate filtration and dewatering of Acid Mine Drainage precipitate using geobags augmented with Capillary Chanel Fibers and internal lateral drainage structures. Laboratory and field research investigated increasing the total solids retention of Acid Mine Drainage precipitate in geobag storage systems. Current geobag design and field application of treated AMD precipitate exhibits limited filtration and drainage efficiency due to the high moisture content (2500%) polymer amended AMD flocculated solids. Capillary channel fibers (CCFs) are geosynthetic yarns formed with microgrooves and set into bundled arrangements capable of wicking water, via capillary action, from fine grained soils. This research studied CCF augmented fabrics and prefabricated vertical drain (PVD) geocomposites positioned mid-depth in geobags with AMD precipitate to accelerate consolidation via a shortened drainage path. This research uncovered a potential decrease in dewatering times using the combination of CCF geotextiles with internal lateral drainage. Laboratory and field scale tests included the Hanging Bag and Geotube Dewatering (GDT) tests. The Hanging Bag testing results indicated that introduction of CCF internal drainage media generally increases dewatering potential (10.86% difference in Total Solids Content). Geotube dewatering tests revealed that the CCF internal drainage media of larger surface area increased dewatering potential (14.38% final Total Solids Content) in contrast to the PVD lateral drainage layer (13.02% final Total Solids Content). Handheld temperature testing of the GDT bags indicated that increasing the CCF geotextile runout length beyond the bag seam increased the lateral dewatering potential (23.4°C average temperature) in contrast to the lateral PVD augmented GDT bag (24.1°C average temperature).