Full Scale Laboratory Testing of a Toe Drain with a Geotextile Sock

This report describes the full-scale laboratory testing (pipe box testing) of a 15-inch-diameter, corrugated, polyethylene toe drain with a knitted geotextile sock, backfilled with a sand envelope material. The test results are compared with previous small-scale and full-scale tests using perforated pipe with 1/8-inch and l/4-inch perforations, but no geotextile. Use of the geotextile optimized toe drain performance both with respect to flow and with respect to loss of the sand envelope. The longterm flow rate was 21 gpm per linear foot of pipe, which was significantly higher (by a factor of 3 to 12) than the earlier tests without geotextile. The total loss of sand envelope was only 50 grams per linear foot of pipe, which was significantly lower (by a factor of 4 to 17) than the earlier tests without geotextile. The test with geotextile was run for 31 days at a constant head of 2.5 feet above the pipe invert with no indication of clogging.