What is the recommended backfill depth over an absorption field?

The recommended backfill depth over an absorption field is typically between 8 to 12 inches. This range is important for several reasons.

First, a backfill depth of 8 to 12 inches ensures that there is enough soil cover to protect the absorption field while still allowing for adequate aeration and microbial activity, which are essential for the treatment of effluent. This depth aids in the natural filtration processes that occur as wastewater passes through the soil, helping to reduce the risk of contamination of groundwater and the surrounding environment.

Additionally, this range helps avoid issues such as compaction or excessive pressure on the absorption field, which could hinder its functionality. If the backfill is too shallow, the absorption field might not be adequately protected; conversely, if it is too deep, it could lead to anaerobic conditions that impair the system’s ability to function properly.

Therefore, maintaining the backfill depth within this specified range is crucial for the effective operation and longevity of an absorption field.