Leakage through Holes in Geomembranes below Saturated Tailings

Experiments conducted to quantify potential leakage from holes in two geomembranes [1-mm-thick linear low-density polyethylene (LLDPE) and 2-mm-thick high-density polyethylene (HDPE)] placed on a silty-sand [underliner hydraulic conductivity (kUL), 1.1 × 10−7 ≤ kUL ≤ 1.2 × 10−5 m/s], or pea gravel (kUL ¼ 1 × 10−2 m/s) underliner (foundation/subgrade) and covered with saturated fine tailings at 65% initial solids content are discussed [tailings hydraulic conductivity (kT), 2.9 × 10−8 ≤ kT ≤ 1.6 × 10−6 m/s]. Tests results show that the overlying tailings, with a kT < kUL, filled the geomembrane hole and had a larger effect on flow through the hole than the underliners examined. For the tested conditions, leakage through 10 and 20-mm-diameter holes were essentially the same whereas the leakage through a 1.5-mm-diameter hole was three orders of magnitude lower. Introduction of a 580 g/m2 nonwoven needle-punched geotextile (GTX) layer between the geomembrane and tailings increased the flow by approximately 60%. A gap below geomembrane hole attributable to a stone on the underliner filled with tailings, which flowed through the hole. The evidence of fines migration through the hole, from the tailings to the underliner is discussed.

Rowe, R.K., P. Joshi, R.W.I. Brachman and H. McLeod. 2016. “Leakage through Holes in Geomembranes below Saturated Tailings.” Journal of Geotechnical and Geoenvironmental Engineering. 143(2), DOI: 10.1061/(ASCE)GT.1943-5606.0001606.

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