Privacy | Legal	Back | Table of Contents| Next	Volume 34 Issue 2  |   2002

To assemble the Eljen drains, 4-inch perforated ADS (Advanced Drainage Systems) pipe was run through the bottom of the 4- by 10-foot panels, and the panels were pinned together. Typically, the entire assembly was dropped in the trench, and staked at the proper grade for backfilling operations (figure 3). A section of HDPE (high-density polyethylene) liner overlapped the Eljen panels to intercept and direct the flows above the panels into the Eljen drains. The downstream ends of the Eljen drains were connected to 4-inch solid ADS piping, or "collector pipes" (figure 4). The collector pipes were then routed to a location where the outflow could be monitored and directed off the landslide. For design purposes, the total drain length for any single collector pipe was limited to 300 feet. The surface water drainage systems were constructed by berming up the sides of the ditch after backfilling operations, then placing a 20-mil HDPE liner over the shaped ditch (figure 5). Initially, the HDPE liner was cut to 6-foot widths, but using 9-foot widths made the installation more efficient.

Figure 3. Eljen drain panels
staked at grade, middle site.

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