Surface water infiltrating through the cover soil will accumulate above the barrier layer and generate detrimental pore water pressure if it is not properly drained. Excessive head buildup due to inadequate drainage can cause catastrophic failure of the cover, numerous seepage-induced landfill slope failures have been recorded and analyzed to confirm this.
TENAX TENDRAIN geocomposites and TENAX GNT provide the highest flow capacity among any geonet. The long-term in-soil transmissivity of TENAX TENDRAIN is in the order of 6 x 10-3 m2/s at a gradient of 0.1, and 4 x 10-3 m2/s at a gradient of 0.33. Long-term (10,000 hour) testing indicates that TENAX TENDRAIN maintains over 90% of its thickness when exposed to long-term compressive loads. This retained thickness maintains an open flow channel into which geotextiles are kept from intruding and rain water is free to flow.