What is an Above Ground or “Mound” Septic?

Septic systems are common in rural Montana. But, it’s not uncommon for a new homebuyer to be learning about how to properly maintain a septic system for the first time. Like most home systems, special considerations and configurations must be made depending on the natural surrounding environment. Septic systems are no different. A high water table or poor soil conditions pose challenges for traditional septic systems and can lead to potential issues of contaminated ground/well water. Let’s take a closer look at the type of system we might see to match such conditions.

Above ground septic systems, also known as “mound systems,” are a type of septic system that is commonly used in areas with high water tables or poor soil conditions. These systems are designed to handle the excess wastewater from a septic tank and disperse it into the surrounding soil in a way that does not contaminate the groundwater.

Unlike traditional septic systems, which rely on underground perforated pipes to disperse the wastewater, above ground septic drain fields utilize a raised bed of gravel or crushed stone. This bed is usually several feet above the natural grade of the land, and is typically covered with a layer of soil to promote the growth of vegetation.

The main advantage of above ground septic drain fields is that they are less likely to be affected by high water tables or poor soil conditions. In areas with a high water table, traditional septic systems can be prone to failure as the wastewater can saturate the soil and escape into the groundwater. Above ground systems, on the other hand, are less likely to fail as the wastewater is distributed over a larger surface area and the excess is safely discharged above the water table.

Another advantage of above ground septic drain fields is that they are typically easier to maintain. The gravel or crushed stone bed allows for easy access to the system for inspections and repairs, and the vegetation that grows on the soil cover helps to keep the system functioning properly by breaking down organic matter.