From the GMA Techline
Subject: Textured HDPE? We are looking at a stormwater basin about 2-3 acres in size with a 20-30ft side slope at 4:1. We are using 60-ml HDPE smooth and it will be covered with sand. The pond will be partially filled with water most of the time.
Will the sand stay on the slope at 4:1? Some folks say use textured 60-HDPE. Will the textured make that much difference at a 4:1 slope?
Reply: I am firmly in the camp of “some folks.” While sand on smooth HDPE is at or slightly higher than 14 degrees, when you have drawdown of the water the hydrostatic forces are sure to bring the sand covering with it. With textured HDPE you still might have sloughing of the sand within the sand itself but the interface with the HDPE should be adequate.
Bob, don’t give it a second thought; go with double-sided, textured material.