Solid Waste

Challenge. Provide routine operation and maintenance (O&M) services and other engineering and technical support to optimize collection and use of landfill gas (LFG)

Solution. Opened in 1990, the Cerro Colorado Landfill is an operating 390-acre waste disposal facility that accepts approximately 450,000 tons of residential and commercial solid waste each year. The landfill is also permitted to accept and safety dispose of petroleum contaminated soils (from oil spills, leaking storage tanks, etc.). INTERA has provided O&M services for the landfill gas collection and control system (GCCS) which is comprised of 46 LFG collection wells, a blower station, a candlestick flare, condensate recovery system, and a skid-mounted control and data storage system. Our routine work has included well field balancing to New Source Performance Standards (NSPS), flare station monitoring and maintenance, surface emission monitoring, compliance reporting, and greenhouse gas emission monitoring and reporting. INTERA staff (certified as HDPE pipe joiners) have also completed pipeline/header repairs on portions of the GCCS. As part of initiating a gas-to-energy project, the City installed a gas compression skid adjacent to the flare station. INTERA assisted in the startup and shakedown of the gas compression skid which sequesters a portion of the LFG for a gas-to-energy boiler system operating at a remote New Mexico Corrections Department facility. Over two miles of conveyance pipeline between the compression skid and the correctional facility are maintained in accordance with the New Mexico Public Relations Commission, Pipeline Safety Bureau regulations.

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.

Challenge. Operate and maintain systems designed to protect the environment and public health from issues associated with a 77-acre former municipal landfill where over 1.5 million tons of solid waste was placed in an abandoned sand and gravel quarry between 1978 and 1983

Solution. INTERA has provided operations and maintenance (O&M) and related services for a landfill gas (LFG) extraction system and a soil vapor extraction/air injection (SVE/AI) system to address vadose zone and shallow aquifer contamination by volatile organic compounds. For the 60-well LFG extraction system, we have performed well field balancing (optimization of methane concentration), groundwater sampling, and LFG monitoring, and have maintained the blower/flare station condensate recovery system, a pilot system microturbine unit, and indoor methane detection systems. Our efforts have resulted in the LFG extraction system being operational for more than 99.9% of the time. One of our first tasks associated with the SVE/AI system involved troubleshooting injection performance which had degraded over time and could no longer support the needed extraction rate. To improve injection performance, we installed two new injection wells and upgraded components including pre-injection buffering tanks, a new pump-skid building, an injection pump system, pre-injection filters, actuated backflush and injection globe valves, flow meters, and a chemical sequestering agent delivery system. When mineral precipitant started to negatively impact extraction operations, INTERA developed and implemented a well-rehabilitation program using a mild acid and aggressive swabbing and bailing. To permanently address the clogging issue, we designed and installed a sulfuric acid delivery system for pH adjustment of the treated water. This has produced a SVE/AI system operational run time of over 99%. Beyond the routine O&M activities performed at the landfill, INTERA has responded to a number of unique and challenging issues. The perpetual decomposition of waste material causes differential settling. This issue results in unequal stresses to buried and surficial infrastructure and causes drainage issues across the site. To address this, INTERA developed a formal grading and drainage plan for the landfill and have conducted annual grading and drainage work in accordance with this plan. We have removed relic electrical infrastructure that posed a constant hazard to site workers and the public (the landfill site is used for recreational vehicle parking during the annual Albuquerque International Balloon Festival [AIBF]); developed a Public Access Plan; remedied the unequal settlement of the SVE building footings with a new foundation design that allows for adjustments to be made to the building as subsidence continues; and prepared the landfill site for the annual AIBF.