Get matched with top excavation pros in Lewistown, MT

How deep your septic system needs to be into the ground depends on several factors. In extremely cold environments, the tank needs to rest below the maximum frost line, which can be up to six or eight feet deep. The standard burying depth for most systems is between a few inches and four feet below ground level. Depth can also depend on the slope of the landscaping and other property variables. 

A trench that is less than 5 feet deep often doesn't require a protective system. Most residential trenches will not go this deep (the typical residential drainage trench is just 18 inches deep). In the event that an excavator needs to dig more than 5 feet beneath the surface, a protective system is required unless the excavation is in entirely stable rock.

In the United States, a depth of 36 inches (three feet) for underground water lines is the accepted industry standard. This depth varies from location to location based on local conditions. In areas with colder winters, they may be buried deeper to prevent frozen well water pipes : This is usually at least six inches below the frost level. The International Plumbing Code calls for a minimum of 12 inches below grade.

The best type of soil to build on is a mixture of sand and clay, known as loam soil. Loam soil has the best combination of these soil types to build a foundation on. The clay particles help with water retention, so it won’t erode like sandy soil might, and the sandy particles help with drainage, so you won’t see unsafe soil expansion or have an increased risk of leaks from water sitting against your foundation.