TSF Cover Design Calculations Workbook (Including O₂ Diffusion & Water Balance)

The TSF Cover Design Calculations Workbook serves as a practical implementation of cover system theory—particularly for 'dry cover' or 'water balance cover' designs that rely on capillary break layers, low-permeability barriers, and evapotranspiration to minimize infiltration and oxygen ingress. At its core, it applies Fick’s law of diffusion to estimate O₂ flux through unsaturated soil layers, accounting for porosity, saturation, tortuosity, and temperature-dependent diffusion coefficients. Simultaneously, it performs a time-series water balance using daily or monthly climate inputs (precipitation, PET, snowmelt) and soil hydraulic properties (field capacity, wilting point, saturated hydraulic conductivity) to compute infiltration, runoff, evapotranspiration, and soil moisture storage. The coupling of O₂ diffusion and water balance is critical: soil moisture content directly governs gas-phase connectivity and thus O₂ transport—dryer conditions increase O₂ flux but may compromise vegetation survival, while wetter conditions suppress O₂ but risk percolation-induced leaching. The workbook typically includes sensitivity analysis modules, scenario comparison tools, and graphical outputs (e.g., cumulative O₂ mass flux, soil water content profiles), enabling engineers and geochemists to iteratively refine cover thickness, material selection (e.g., sand vs. clay vs. till), and vegetation parameters to meet performance criteria over 100+ year design horizons.