Landfill Liner System

Landfills are designed with "cells" that are lined to prevent groundwater contamination. The liner consists of a two-foot layer of low-permeability,> re-compacted clay soil. Over this layer, a 60-mil, high-density polyethelene (HDPE) plastic liner is installed to complete the composite liner system, covering the entire bottom and sides of the landfill cell.

A blanket of geotextile fabric, composed of synthetic, felt-like fibers, is laid above the primary liner system, along with a geonet made of mesh-like plastic. Together, these prevent fine clay particles from clogging the leachate collection layer and promote removal of leachate from the liner surface. Click here for a diagram illustrating the anatomy of a landfill.

Strick construction guidelines must be followed in constructing the liner systems, which are summarized below:

• The qualified liner installation contractor must have certified personnel and equipment to perform the work.
• Personnel performing field liner seaming are qualified by experience and by passing field seaming tests.
• Field seams are oriented parallel to slopes to reduce stress on the seams. Adjacent geomembrane panels will be overlapped to facilitate a strong, double seam. Peel tests are performed on all field seams to ensure strength and seam integrity.
• Final acceptance of the geosynthetic liner system is based on certification by an independent, licensed engineer and quality assurance consultant that certifies the geosynthetic materials have been properly installed
• Following approval of a lined area by a quality assurance inspector, protective cover materials are placed.
• Liner installation/certification reports are submitted to the TCEQ for review and approval.