What condition requires a solids retention tank to be installed before a septic tank?

The requirement for a solids retention tank to be installed before a septic tank is primarily due to the use of a garbage grinder. When a garbage grinder is utilized, it introduces a larger volume of solid waste into the sewage system. This can overwhelm a standard septic tank, which is designed to separate and treat organic waste and solid materials.

The function of a solids retention tank is to capture and break down the extra solids produced by the garbage grinder before they enter the septic tank. By doing this, the solids retention tank helps to prevent clogging and ensures that the septic system operates efficiently, reducing the risk of system failure. The introduction of additional solids without proper management could lead to problems such as backups, overflows, and increased maintenance needs for both the solids retention tank and the septic tank.

Other conditions, such as a high water table, low soil permeability, or a site slope greater than 20%, may pose challenges to septic systems but do not specifically necessitate the installation of a solids retention tank before the septic tank. These factors typically relate more to drain field performance and overall system design rather than the handling of additional solid waste from appliances like garbage grinders.