Plastic material may be used where in embankment construction?

Plastic material may be used where in embankment construction?

• A. Inside and outside of 1:2 slope, above water table, or 4-5 ft beneath base
• B. Only on the surface
• C. Only in foundation
• D. Not allowed

Answer: (A)

In embankment work, plastic material acts as an impermeable barrier to control seepage and protect stability. Placing it on both faces of the slope creates dual barriers against seepage paths that could travel along the soil-structure interface, which helps prevent piping and slope failure. Installing the liner in zones above the water table keeps it in a dry, installable region and reduces the risk of damage from high pore pressures, while still effectively blocking horizontal flow through the fill. Adding a cutoff at a depth such as 4–5 feet below the base provides a deeper barrier that intercepts seepage trying to move under the foundation, further protecting the core and foundation from pore-pressure buildup. That combination—covering both sides of the slope, in the region above the water table, or at a shallow-to-deeper depth beneath the base—fits typical practice. Placing plastic only on the surface wouldn’t prevent seepage pathways inside or beneath the fill, placing it only in the foundation wouldn’t protect the slope, and says “not allowed” is not accurate for properly designed projects.

In embankment work, plastic material acts as an impermeable barrier to control seepage and protect stability. Placing it on both faces of the slope creates dual barriers against seepage paths that could travel along the soil-structure interface, which helps prevent piping and slope failure. Installing the liner in zones above the water table keeps it in a dry, installable region and reduces the risk of damage from high pore pressures, while still effectively blocking horizontal flow through the fill. Adding a cutoff at a depth such as 4–5 feet below the base provides a deeper barrier that intercepts seepage trying to move under the foundation, further protecting the core and foundation from pore-pressure buildup.

That combination—covering both sides of the slope, in the region above the water table, or at a shallow-to-deeper depth beneath the base—fits typical practice. Placing plastic only on the surface wouldn’t prevent seepage pathways inside or beneath the fill, placing it only in the foundation wouldn’t protect the slope, and says “not allowed” is not accurate for properly designed projects.