Gary, a “mound System” is a soil absorption system, or leach field which is constructed in a mound of soil, typically hauled onto the site because of site constraints such as high ground water, or shallow soils over bedrock. The mound system was developed at the University of Wisconsin, and is also known as “The Wisconsin Mound”. Typically, septic tank effluent is pumped up into the mound system so that the effluent is filtered through the 3 or 4 feet of soil before it is returned to the environment. Much information is available on the Internet regarding this technology. JWA