Midland’s Cell 7 consists of a 26.8-acre footprint at a maximum excavated depth of 35 feet. No portion of the cell had been previously excavated, resulting in almost 1.4 million cubic yards of excavation.

The liner system consists of a geosynthetic clay liner overlain by a 60-millimeter geomembrane liner installed on prepared subgrade in accordance with the site’s Soil and Liner Quality Control Plan (SLQCP). A leachate collection system overlaying the geomembrane liner was installed for liquid removal. A geocomposite drainage layer and perforated leachate collection pipe were included in the leachate collection system. A gravel “chimney” is encapsulated in a geotextile fabric that surrounds the pipe. The liner construction sequence was completed with a two-foot thick layer of protective cover soil.

A Geosynthetic Clay Liner Evaluation Report (GCLER) and Geomembrane Liner Evaluation Report (GLER) were prepared upon completion of liner construction. The reports document every phase of construction including independent third-party testing of liner materials, liner roll delivery and deployment, and soil thickness verification.

Additional construction items included removing an existing oil pipeline that transected the landfill, construction of a new heavy duty asphalt access road and abandonment of an existing groundwater monitoring well.