The top of the absorption field gravel should be covered with what type of material?

The correct answer is that the top of the absorption field gravel should be covered with a permeable material. This is crucial because the primary function of an absorption field, commonly utilized in septic systems, is to allow wastewater to be treated as it percolates through the soil.

Using a permeable material ensures that air can circulate freely and that wastewater can flow from the gravel into the surrounding soil. This supports the natural absorption and treatment of the wastewater, promoting the necessary biological processes that break down contaminants. Materials that are permeable, such as landscape fabric or certain types of geotextiles, are designed to allow moisture and air to pass through while preventing larger soil particles from clogging the gravel.

In contrast, tar paper and plastic are impervious and would completely block water flow, preventing the essential interaction between wastewater and soil. Treated paper, although it may have some permeability, does not provide the structural integrity and durability needed for long-term use in an absorption field. Thus, covering the absorption field gravel with a permeable material is vital for ensuring its functionality and effectiveness in treating wastewater.