Challenge. In support of the safe redevelopment of portions of this former landfill site and surrounding properties, determine depth of waste and soil cover and monitor landfill gas (LFG) within landfill buffer zone

Solution. The former San Antonio Landfill site occupies 40-acres in northeast Albuquerque that is now surrounded by residential and commercial properties. The landfill accepted municipal waste from 1968 until 1970, at which time it was capped and informally closed. Portions of the site are owned by both the City of Albuquerque and private land owners. Sale and redevelopment of the site has been challenging due to environmental and engineering concerns, including the presence of methane gas and differential settlement concerns arising from the compressibility of the underlying waste material. Despite this, significant development has occurred on the western portion of the site (including a hotel, restaurant, and the New Mexico Environment Department [NMED] District I office building). Residential neighborhoods are to the north, east, and south of the landfill. INTERA completed a Phase II site investigation consisting of a geophysical survey to estimate the depth of waste and cover across the landfill site. This included an initial ground conductivity survey over the entire site, followed by focused electromagnetic and magnetic surveys of selected areas. Resistivity soundings were also performed to provide as much data as possible. Based on data from the geophysical survey, we concluded that the depth of soil cover across the former San Antonio Landfill ranges from 2 to 6 feet, and it is very unlikely that landfill related waste will be encountered in surficial soils. In support of the site developer of the NMED District 1 office building, INTERA staff have completed additional investigations of the extent of buried waste, provided design, on-site inspection, and oversight of waste excavation and installation of a LFG abatement system, and conducted quarterly methane monitoring and reporting. For other owners and developers of properties within the LFG buffer zone of the former landfill, we have installed and monitored numerous methane monitoring wells and successfully negotiated a modification to the buffer zone boundary to support property redevelopment projects in close proximity to this former landfill.