Desiccation and Cracking Behavior of Three Compacted Landfill Liner Soils

Tests were conducted to investigate desiccation cracking of three compacted liner soils obtained from local landfills in southeast Michigan. The soils had low plasticity with varying fines content. Large-scale samples of the soils were subjected to wetting and drying cycles. Surficial dimensions of cracks and suction in the soils were monitored. Surficial dimensions of cracks were quantified using the crack intensity factor (CIF), which is the ratio of the surface area of cracks to the total surface area of a soil. All of the soils were subjected to a compaction–dry cycle (i.e. soils were allowed to dry after compaction) and a subsequent wet–dry cycle. An additional sample of one of the soils was subjected to a compaction–dry cycle and three wet–dry cycles. The maximum CIF obtained in the tests was 7% and suctions exceeding 6000 kPa were recorded. It was observed that cracking was affected by the fines content of the soils. In general, high suctions, rapid increases in suctions, and high amount of cracking were observed in soils with high fines content, with less cracking observed in soil with low fines content. In addition, it was observed that cracking increased significantly due to addition of moisture to the soils. The CIF for wet–dry cycles were significantly greater than the CIF for compaction–dry cycles. Subsequent to moisture addition to the soils, critical suctions that caused a significant change in CIF during the drying cycles were wet–dry cycles, the amount of cracking did not change significantly after the second cycle

Design of Zebra Mussel Control Measures for Hydro-Electric Power Projects

Zebra mussel, Dreissena polymorpha, is a biofouling organism that lives generally in freshwater ecosystems. Zebra mussel infestation has occurred at various freshwater structures and systems including raw water intakes, industrial and domestic distribution pipelines, and hydropower facilities at its native regions as well as distant locations. A study was conducted to perform risk assessment and to develop preventive measures for zebra mussel infestation at a planned hydroelectric power plant (Alpaslan II HEPP) in southeast Turkey. Zebra mussel is native to Anatolia region and existing hydropower facilities have significantly been affected by mussel infestation. The risk assessment was conducted by considering effects of various factors on zebra mussel infestation. The factors included environmental conditions, factors related to materials used in construction of various components of a HEPP as well as the susceptibility of various components to infestation due to routine operation of a facility. Quantitative study of head loss due to major infestation for Alpaslan II HEPP indicates approximately 4% reduction in power generation. A two-step process is proposed to prevent mussel infestation at hydroelectric power plants. The method makes use of the water hammer effect that occurs during rapid shutdown of the turbine combined with an automated system for providing chemicals to the power plant water to remove and kill zebra mussels associated with various components of a facility. The proposed system constitutes a proactive-reactive chemical treatment system

Impact of Soil Type and Compaction Conditions on Soil Water Characteristic

Tests were conducted to determine the variation of water content and pore water suction for compacted clayey soils. The soils had varying amounts of clay fraction with plasticities ranging from low to high plasticity. The unsaturated soil behavior was investigated for six conditions, covering a range of compactive efforts and water contents. The experimental data were fit to four commonly used models for the water content-pore water suction relationship. Each model provided a satisfactory fit to the experimental data. However, the individual parameters obtained from the curve fits varied significantly between models. The soil water characteristic curves (SWCCs) were more sensitive to changes in compaction effort than changes in compaction water content. At similar water contents, the pore water suction increased with increasing compaction effort for each compaction condition and soil type. For all compaction conditions, the lowest plasticity soils retained the smallest water content and the highest plasticity soils retained the highest water content at a specified suction. In addition, SWCCs for soils compacted in the laboratory and in the field were similar