Figure 2. Separation distances for the mound system.
Mound systems can be used in areas of Ohio with seasonal high water tables, shallow depths to a restrictive soil layer or bedrock. A minimum depth of 24 inches of unsaturated and permeable soil is a prerequisite for a mound system design using this bulletin and Bulletin 829. The permeability of the soil must be at least 0.5 inch per hour and no more than 20 inches per hour.
A mound system must be positioned in the landscape along the contour of the lot. Separation distances of 50 feet from drinking wells and of 10 feet from property lines are required for the mound system, as shown in Figure 2. Mounds are long and narrow to insure that wastewater can infiltrate the soil beneath and move away from the mound without surfacing. Ideally the mound should be as long and narrow as possible along the contour, but no shorter than is prescribed for the design linear loading rate. Constructing a mound shorter and wider than recommended will result in surfacing of partially treated wastewater.
Figure 2. Separation distances for the mound system.