A mixed-media filter consists of about ________% garnet, ________% sand, and ________% coal.

The composition of a mixed-media filter is crucial for its effectiveness in water treatment. In this case, the correct proportion is approximately 10% garnet, 30% sand, and 60% coal.

Garnet is often used due to its high density and durability, which enhances the filter's ability to capture larger particulates. Sand serves as a suitable media for finer filtration, bridging the gap between the larger garnet particles and the finer coal layer. Coal, with its absorbent properties, plays a significant role in removing organic matter and contaminants from the water.

This particular percentage distribution allows for a balanced filtration system that takes advantage of the strengths of each medium, leading to more efficient pollutant removal. The specific proportions maximize the filter's performance in effectively treating various types of surface water, which is essential knowledge for someone preparing for the TCEQ Class B Surface Water License. Other options do not provide this optimal performance, highlighting the importance of understanding the correct application of materials in water treatment systems.