Geocomposite Edge Drain Evaluation on Ontario Highway 402 at Strat roy

Presented are results from excavations made to evaluate the performance ot- Geocomposite Edge Drains (GED). The highway of the areas investigated was built in 1981 over a stiff (cu= 50 to 100 kPa) clay subgrade (LL=40; PL=20; PI=20) as part of Ontario s freeway system (i.e. limited access divided highway). The GED was placed in 1990 and consisted of a plastic core 300 mm wide with 25 mm high cusps all wrapped in a nonwoven geotextile. The excavations clearly showe4. – differences between the installation concept and actual construction. First, the GED was unable to prevent the Ulderlying clay from pumping. Second, the GED installed was not square ended. Third, permeability tests on the backfill showed that the granular backfill was nearly 1000 times less permeable than the geotextile of the GED. These and Qther factors resulted in several valuable and practical conclusions.