Wisconsin Mound Soil Absorption System and Area FillPractice Exam

What type of fill can cause system failure if it contains excessive amounts?

1. Sand

2. Silt and clay

3. Organic matter

4. Gravel

The correct answer is: Silt and clay

The correct choice, which indicates silt and clay, highlights the specific issues these materials can cause in a soil absorption system. Excessive amounts of silt and clay in fill material can lead to compaction and reduced permeability, hindering the ability of the soil to absorb and filter wastewater effectively. This lack of drainage capability can cause wastewater to pool or back up, eventually resulting in system failure. While sand and gravel are often used in systems due to their high permeability and excellent drainage properties, organic matter, when present in appropriate quantities, can enhance soil structure and nutrient content. However, an excessive amount of organic matter can also lead to complications, but the primary issue with system failures is significantly associated with silt and clay. Thus, understanding these materials' behavior in absorption systems is essential for proper installation and maintenance.