A construction project involves stockpiling topsoil on a sloped area adjacent to a natural waterway. Which erosion control measure is most effective for preventing sediment runoff from this specific area during a heavy rainfall event?

Question: A construction project involves stockpiling topsoil on a sloped area adjacent to a natural waterway. Which erosion control measure is most effective for preventing sediment runoff from this specific area during a heavy rainfall event?

Answer options: ✅ Installing a silt fence at the toe of the slope between the stockpile and the waterway.

• Hydroseeding the entire stockpile immediately after formation.
• Placing large riprap stones along the entire length of the waterway bank.
• Constructing a temporary access road around the stockpile.

Correct answer: Installing a silt fence at the toe of the slope between the stockpile and the waterway.

Explanation: For preventing sediment runoff from a disturbed area like a topsoil stockpile on a slope, a silt fence placed downslope is highly effective. It allows water to pass through while retaining sediment, as outlined in erosion control best practices and OPSWA HEO training.