LDCR systems

This section presents an overview of collector design and materials, followed by a discussion of the three parts of a liquid management system the LCRS above the primary liner, the secondary leak detection, collection, and removal (LDCR) system between the primary and secondary liners, and the surface water collection system above the closure of the completed facility. The section concludes with a discussion of gas-collector and removal systems. 

The LDCR system is located between the primary and secondary liners in landfills, surface impoundments, and waste piles. It can consist of either granular soils (i.e., gravels) or geonets. 

For a geonet LDCR system, the flow rate for the geonet is determined in the laboratory by using the ASTM D4716 test method, and the value is modified to meet site-specific situations. The geonet flow rate DR is then determined in the same way as for the granular system. No pipe network is needed. 

U.S. EPA specifies that the minimum detection time for the leachate entering the LDS of an LDCR system is <24 h. Response time calculations are based on velocity in the geonet and/or granular soil drainage layer. Darcy s law is used to calculate flow velocity in the geonet, and a true velocity must be used for granular soil. 

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