The Caja Del Rio Landfill continues to fill its latest solid waste disposal cell, Cell 5B. A total of 25 blast events from October 7, 2013, to February 21, 2014, were required to create space for liner construction, which cost $1.6M. Seismic monitors at various locations verified that the blasting activity created no potential for property damage to the landfill’s neighbors. Approximately 279,000 cubic yards of basalt rock was excavated and removed at a cost of $7.19 per yard.
The subgrade soil was prepared for the installation of a geosynthetic liner. The liner is a low permeable barrier which is constructed under the landfill before disposal to contain leachate and prevent groundwater contamination. The liner system includes a layer of a low-permeability, geosynthetic clay (GCL) liner on the bottom. The GCL liner acts as a primary seal at a specified moisture content to provide additional protection for the liner system. Over this layer, a 60-mil, high-density polyethylene (HDPE) secondary plastic liner is installed to cover the bottom and sides of the landfill cell. The HDPE liner is smooth on the landfill bottom and textured on the landfill sides to increase friction and prevent slipping. The liner, which is resistant to chemicals and damage, is then welded together and tested to ensure a continuous seal in accordance with regulatory requirements. A blanket of geotextile fabric, composed of synthetic fibers, is laid above the liner and a geonet made of mesh-like plastic is added under the geotextile on the sides of the landfill to prevent fine clay particles from clogging the leachate collection layer and promote removal of leachate from the liner surface. Normally, the entire leachate collection layer would be comprised of two feet of basalt gravel on the liner that collects leachate and allows it to drain by gravity to the leachate collection pipe system, but this cell is different. For the first time in New Mexico, glass cullet from bottles processed at the Buckman Road Recycling and Transfer Station (BuRRT) provided a portion of this drainage layer.
The liner installation of the Cell 5B was completed in December of 2014. The cell has a surface area of approximately 10 acres with a disposal capacity of 6 years, and will accept waste until 2020. Cell 6B construction will begin in the Spring of 2019 and open in 2020. The cell will require no blasting and have a disposal capacity of 5 years. The estimated cost of liner installation for Cell 6B is $1.6 million. When Cell 6B is full, the vertical expansion approved by the New Mexico Environment Department will be built out during the next 10 years.