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DIFFERENTIAL LANDFILL SET TLEMENT-5%FINAL CLOSURE SLOPE <br /> :DIFFERENTIAL LANDFILL SETTLEMENT MODEL DESCRIPTION <br /> t <br /> ;This is a spreadsheet model to estimate landfill differential settlement assuming secondary type settlement <br /> :after closure due primarily to decomposition of refuse.The following generally describes the structure of <br /> :the model: <br /> 1. The model consists of 10 horizontal " lifts" of waste laid out as a series of cells. <br /> 12. A base settlement percentage and a differential reduction percentage is applied to each cell to produce <br /> �a post-settlement depth for the cell.The differential reduction percentage in each cell is calculated by <br /> ]multiplying the differential settlement percentage by a random number between 0 to 1. For example,if the <br /> ;base settlement is 10% and the differential settlement is 5%,then the range of settlement for the cell will be <br /> is random number between 10% to 15%. <br /> '3. It is assumed that"bridging"of the refuse will tend to decrease in influence of differential settlement. <br /> ;Also the vertical summation of cells may overestimate the effect of differential settlement by not accounting <br /> ,for the horizontally random distribution of the refuse.To compensate,the differential settlement of the cell <br /> ;is a weighted average of the main cell and the.four adjacent cells as follows: <br /> [(STARTING LIFT HEIGHT x (BASE SETTLEMENT% + (RANDOM#x DIFF SETTLEMENT%)) <br /> +AVERAGE OF ADJACENT CELL HEIGHTS]/2 <br /> 4. The vertical column of cells is then summed to estimate a post settlement surface elevation. From these <br /> elevations and grid spacing,the final slope between cells is calculated. For demonstration purposes a <br /> single cross section is graphed. <br /> i <br /> i <br /> i <br />