Standard subsurface system criteria. To be approved for a standard-subsurface system, each site must comply with all conditions.

The effective soil depth should be 30 inches below the ground surface, as shown in Table 3. Between the soil layer and the absorption facility’s bottom, a minimum 6-inch separation should be maintained.

Except in areas where DEQ has determined that less separation is not likely to degrade groundwater quality or pose a threat to public health, the permanent water table must not be lower than 4 feet from the absorption facility’s bottom. These areas are exempt from the requirement that the permanent water table is at least 24 inches below ground level.

Temporary water tables must not be less than 24 inches below the ground. An absorption facility cannot be installed below the top of the temporary table.

Groundwater interceptors can be used to drain or intercept water from absorption areas on sites that have sufficient slope to allow proper drainage. Before approving a site, an agent might require that the site be shown to be water-drainable. Groundwater interceptors can be an integral part of the system, but they do not have to meet setback requirements for property lines, streams, lakes, or other surface water bodies required to the wastewater absorption zone.

Soil with very rapid or rapid permeability must be at least 36 inches below the ground surface. Between soil with rapid or very fast permeability and the bottom absorption trenches, a minimum 18-inch separation should be maintained.

This post was written by Tanner Brown. Tanner is the Owner and operator of Greenbar Excavation. Greenbar Excavation is a fully licensed, insured, and accredited Excavation company based in Prineville Oregon. Greenbar Excavation is one of the top Septic Tank replacement companies in Central Oregon. Don’t look further, go with the company with your best interest in mind!