 |
2007 Ground Water Summit |
Monday, April 30, 2007
4:30 p.m. - 7:30 p.m.
Tuesday, May 1, 2007
9:30 a.m. - 1:30 p.m.
Tuesday, May 1, 2007
4:30 p.m. - 7:30 p.m.
Porosity and Permeability of Bimodal Sediment Mixtures Using Natural Sediment
Porosity and permeability are well known parameters that affect the flow of groundwater in the subsurface and have significant implications in fate and transport modeling. However, little has been done to quantitatively examine the relationship between porosity and permeability and the grain size distribution of bimodal sediment mixtures. Even less has been done to examine this relationship directly on natural sediment. The intent of this poster is to better define this relationship using fluvial grain size components. The fluvial sediment mixtures used in the experiment were created from the bimodal combination of grain size component percentages, which were systematically varied. Measurements were taken on these sediment mixtures to determine porosity values. These values were computed by inputting the measurements into an expanded fractional packing model for porosity. The expanded fractional packing model for porosity represents mixtures in which finer grains approach the size of the voids among the pre-mixed coarser grains. With the porosity values computed, a grain size statistical method was utilized to derive estimates for permeability, which were used to compare to the permeability measurements determined in the lab for accuracy. These lab measurements were taken on the sediment mixtures using water and air based methods. The water based method consisted of constant head permeameter measurements, which were taken as a standard of comparison for the air based permeameter measurements. Porosity and permeability data for bimodal mixtures of fluvial sediment, varied by grain size component percentages, will help to provide a more accurate means of estimating the parameters of porosity and permeability in the subsurface, which will ultimately improve the predictability of a fate and transport model.