In a partially saturated system the accumulation of colloid at interfaces such as air-water (AW), solid-water (SW) and air-water-solid (AWS) interfaces depend on the area of those interfaces and its accessibility to the water phase. Accumulations of colloids near the three-phase contact line (AWS) depend on the water volume associated with that line. The area of interfaces and contact line can be varied independently by adjusting the capillary pressure (or moisture content) and/or contact angle. In the present study, we keep the contact angle constant and vary only capillary pressure to vary interface configurations and areas of AW and AWS interfaces. Experiments are being conducted using 3D pore-scale micromodels, made from rectangular capillary tube with inner dimension of 100 μm by 1000 μm, packed with glass beads which have average diameter of 75 μm, and with fluorescent latex microspheres with diameter of 1 μm. Both capillary tube and glass beads were treated with acid to achieve uniform hydrophilic surface. Using a fast laser scanning microscope, volumetric (3D) images are collected in near real time during dynamic flow conditions as well as static conditions. The images will allow for investigation of the air and water phase configurations and its effect on colloid retention at the interfaces. An advanced confocal software Volocity is used for particle tracking and image analysis to quantify the number of particles retained for specified areas. Modeling involves Progressive Quasi-static Algorithm implementation of level set method to predict the configuration of fluids in porous media by varying the pore space geometry (square and equilateral triangles sphere-sphere configurations) and interfacial (capillary) pressure. Results from the micromodel experiments will be used to validate the model.