the initial leakage volume was changed iteratively in order to fit the measured leakage curve to the laboratory value of Sy. The curve of Sy versus time will be material specific and will be a function of material shape, texture and mineralogy. Obtaining a laboratory value for Sy will enable estimations of the total flow from the material over an extended period of time. However, the curve must be generated in order to estimate flows in the short term, and leakage must be measured immediately once the layer is sealed up. Using the equation generated from Figure 3 for Sy, the theoretical daily flow rate was calculated and is shown in Figure 4. This theoretical curve is shown with the actual measured flow rate and the average temperature. Figure 4 shows how the measured flow responded to increasing temperatures by arching away from the theoretical curve until temperatures decreased. Identifying the culprit and matching the phenomenon to the data was straightforward. The more difficult part is to figure out how to keep this from happening in order to get sites permitted to operate in a timely manner. The type of material used for the LDS will be the biggest factor in whether and for how long it will continue to drain. Clean gravel has a much higher Sy than dirty gravel. In fact, Sy values of 0.21-0.25 are common for clean gravel and 0.05-0.07 for clayey gravel. As with most sites, stockpiling gravel and hauling it to the cell at the case study site caused clayey fines to be placed along with the gravel. Due to precipitation on the day of ELL testing www.GeosyntheticsMagazine.com 0420GS_p16-23.indd 21 21 3/23/20 11:42 PMhttp://www.layfieldgroup.com http://www.GeosyntheticsMagazine.com