Which disposal system compensates for shallow soils?

• A. Conventional Septic System
• B. Mound System
• C. Shallow Disposal System
• D. Drip Irrigation System

Answer: (B)

When soils are shallow, there isn’t enough depth for a conventional drain field to reliably treat and absorb effluent. A mound system addresses this by creating an elevated absorption area. It places a layer of sand and a buried drainage zone on top of the ground, forming a raised bed that effectively increases the depth and improves the infiltrative capacity. This design lets effluent percolate through the mound rather than through the shallow native soil, providing better treatment and reducing the risk to groundwater in conditions of limited soil depth or high water tables. Conventional septic systems rely on adequate native soil depth, so they’re not suitable for shallow soils. Drip irrigation disperses effluent differently and doesn’t specifically fix the depth limitation, and a “shallow disposal system” isn’t a standard remedy in this context.