Both sand mounds and absorbtion fields work under the same concept. Clarified liquid waste is dispersed evenly amoung the area by way of a pipe network. The pipes have 3/16" holes around the perimeter to assist in an even distribution throughout the field. The only difference in the two fields other than physical appearance is liquid transport to the field. The sand mounds require a dosing tank so that the effluent can be pumped to the top of the mound. Liquid from a septic tank destined for the adsorbtion fields is gravity fed through a distribution box and into the pipe network leading into the field.