The Basics
Soil evaluations are done to determine if the soils and groundwater conditions on a property are suitable for use as an on-site sewage disposal system. All properties not served by public water and sewer must have this test before beginning construction of any structure with plumbing. If an area of acceptable soils is found, a plat is established of the area to be designated for sewage disposal. Perc tests are performed when contemplating new construction, adding on to land already served by on-site systems and when a system fails.
Considerations for Constructing Additions
In cases involving additions to houses, the Environmental Programs researches records to try and determine the capacity of an existing system. If the proposed addition will potentially increase sewage flow, approval of the addition requires establishing adequate sewage disposal capacity. In some cases, properties with older homes may be required to undergo a perc test.