Cross-sections of the SLD from Check 19 to the terminus are shown in Figure 4.4.1. There will be water flowing in the SLD during the sediment surveys. In order to obtain accurate thickness measurement, it is proposed that, at any given location, a measurement be taken along the length of the slope of the lining from the top of the lining to the water surface, and then, that a probe be used to take the measurement from the water surface to the sediment in the center of the SLD. It is likely that the sediments are not of uniform width across the SLD. Representative sites will be measured at various locations to confirm whether a measurement of the sediment taken in the center is accurate. The thickness of sediment, therefore, will be measured and determined arithmetically. Figure 4.4.2 illustrates the variables to be used in the calculation.