Mound Septic Systems in Hattiesburg, MS: What Homeowners Need to Know

If you have purchased a home in the Pine Belt and noticed a raised earthen mound in the yard — sometimes subtle, sometimes quite prominent — you likely have a mound septic system. These systems are common on Hattiesburg-area properties where native soil conditions do not meet minimum percolation standards for conventional drainfield installation. Understanding how your mound system works is essential for maintaining it properly.

Why Mound Systems Are Used in Hattiesburg

Mound systems are specified when native soil fails to perc — when percolation testing reveals that the soil absorbs water too slowly to safely process septic effluent. In Forrest and Lamar County, the heavy clay geology means that a significant portion of residential lots fail conventional perc testing. Rather than prohibit development on these lots, MS regulations permit the construction of a mound system using imported sandy fill material that provides adequate percolation above the native clay.

How a Mound System Works

In a mound system, effluent from the septic tank is pumped — using a pressure dosing pump — to a distribution network buried within the elevated mound of sandy fill. The effluent percolates down through the sand, receiving final treatment from soil bacteria, before reaching the native clay layer below. The elevated position and sand fill bypass the percolation limitations of native soil.

The pump is a critical component that has no equivalent in conventional gravity systems. It must be inspected regularly, and the pump chamber should be pumped during routine service visits to remove accumulated solids that the pump cannot handle.

Maintenance Differences from Conventional Systems

Mound systems require everything a conventional system requires — tank pumping every 3 to 5 years — plus additional attention to the pump and pump chamber. The distribution network within the mound should be inspected periodically to ensure even distribution across all zones. The mound surface should be maintained with grass cover and never driven over — vehicle weight can compact the fill and crush distribution pipes.