Problem 2. Leachate Collection System (50 pts) a. A rock storage pile is being designed for a mine in West Virginia. The pile is lined with reinforced GCL overlain by a 1.5 mm thick HDPE geomembrane. A heavy non- woven geotextile is placed on top of the geomembrane. Because the rock is porous (K 102 cm/s), it is used as the main LCS stone and no additional leachate collection stone is being installed. Specify the base slope required to keep the head below 25 cm if the design storm is 0.8 cm rain/day and the pipe-to-pipe lateral spacing is 60 m Is this rock a reasonable material to replace the LCS stone? (20 pts). b. Why is coarse, rounded gravel usually specified for leachate collection stone? Why is a geonet often used in place of leachate collection stone on a side slope? (10 pts) c. A plan of landfill cell is shown in the figure below, in which AB is a leachate collection pipe. The bottom of the cell has a 2% slope with a peak leachate generation rate of 0.943 in/day. The slope of the pipe is 1%. Approximately 200 ft of waste with a unit weight of y waste =70 pcf is placed on the pipe. Design an HDPE perforated pipe to meet drainage and mechanical requirements. (20 pts) F E 1 45 ft 2% 2%. 1% B A 291 2.1 80 ft D 500 ft Problem 2. Leachate Collection System (50 pts) a. A rock storage pile is being designed for a mine in West Virginia. The pile is lined with reinforced GCL overlain by a 1.5 mm thick HDPE geomembrane. A heavy non- woven geotextile is placed on top of the geomembrane. Because the rock is porous (K 102 cm/s), it is used as the main LCS stone and no additional leachate collection stone is being installed. Specify the base slope required to keep the head below 25 cm if the design storm is 0.8 cm rain/day and the pipe-to-pipe lateral spacing is 60 m Is this rock a reasonable material to replace the LCS stone? (20 pts). b. Why is coarse, rounded gravel usually specified for leachate collection stone? Why is a geonet often used in place of leachate collection stone on a side slope? (10 pts) c. A plan of landfill cell is shown in the figure below, in which AB is a leachate collection pipe. The bottom of the cell has a 2% slope with a peak leachate generation rate of 0.943 in/day. The slope of the pipe is 1%. Approximately 200 ft of waste with a unit weight of y waste =70 pcf is placed on the pipe. Design an HDPE perforated pipe to meet drainage and mechanical requirements. (20 pts) F E 1 45 ft 2% 2%. 1% B A 291 2.1 80 ft D 500 ft