What is the recommended depth of a cutoff trench in embankment construction?

The recommended depth of a cutoff trench in embankment construction is generally set at 4 feet below existing grade to effectively minimize water movement under and through the embankment. This depth is essential for the structural integrity of the embankment, as it ensures that the water table is sufficiently lowered, reducing the risk of saturation and potential failure due to water pressure. It also allows for a stable base that can handle any potential seepage, thus improving the overall durability and performance of the embankment.

By constructing the cutoff trench at this recommended depth, engineers can create a more effective barrier against underground water flow, thereby enhancing the embankment's ability to withstand environmental factors. This careful design is critical in preventing erosion and maintaining the longevity of the embankment structure, making the 4-foot depth the best practice in such construction scenarios.