Los Alamos Airport Landfill

Location: Los Alamos, New Mexico
Client: U.S. Department of Energy
Project Description

CTI served as Prime Contractor to the Department of Energy (DOE) for replacement of the existing cover system at the Los Alamos County Airport Landfill. The existing hazardous waste landfill had been operated by DOE from 1943-1973 for disposal of household and office waste generated by the Los Alamos National Laboratory. The impermeable asphalt cover system and 5 concrete hangar pads were constructed in 2007 and had since experienced significant differential settlement, resulting in heavy pavement cracking and rendering the concrete hangars unusable. In addition, the cracking allowed water infiltration into the underlying waste, which generated methane in excess of acceptable levels in the passive collection system. Based on those excessive methane levels, the New Mexico Environmental Department required that the DOE either install an active collection system or replace the damaged cap.

CTI self-performed the cap reconstruction soils work, including removal and off-site recycling of the existing 6 acres of asphalt pavement and concrete hangars, salvage of the existing underlying aggregate base layer, excavation and relocation of over 5,000 cubic yards of waste, backfill of the resulting waste excavation with salvaged aggregate, import and placement of over 45,000 tons of cover soil, and installation of two riprap-lined perimeter drainage channels. Waste was removed from the west side of the landfill to facilitate construction of a new 10,000 square foot concrete hangar pad and adjacent asphalt apron. Excavated waste was spread across the center of the remaining landfill subgrade. CTI subcontracted the placement of both the concrete slab and asphalt pavement to local contractors and managed their on-site schedule and work quality. To reduce the potential for additional water infiltration, CTI performed the project in phases, with existing pavement removal, waste excavation and relocation, and cover soil installation being performed on the northern 2/3 of the landfill prior to removal of existing pavement and cap installation on the southern 1/3 of the landfill.

Project challenges included frequent design and specification changes, strict as-built survey requirements at each phase of work, and winter weather. Due to snow and freezing temperatures, CTI performed a 2-month winter shut down. Other challenges included dry and windy spring weather resulting in high levels of fugitive dust, which required constant dust control. Also, the specified density range for the soil placement was approximately 85% to 95% of optimum, which required establishing a reliable compaction program and limiting haul truck traffic on previously approved areas of cover soil. CTI field and site management participated in weekly calls with the client’s management team and project engineer to discuss project progress and schedule, procurement and submittals, quality control and assurance, site safety, storm water and pollution prevention, and project issues or concerns. In addition, CTI site management interfaced with the project engineer and DOE project management on the project site daily. Despite facing the site challenges and safety concerns associated with heavy equipment construction, the project was completed safely with over 9,500 field labor hours and within the imposed construction schedule.

Project Highlights
  • $3M+ FFP Contract
  • Zero Injuries or Safety Incidents
  • Construction of 6-acre Landfill Evapotranspiration (ET) Soil Cover
  • Import of over 45,000 tons of cover soil
  • Demolition and disposal of 6 acres of existing asphal pavement and concrete hangar slabs
  • Excavation and relocation of over 5,000 CY of waste
  • Installation of perimeter stormwater control channels
  • Installation of new 10,000 SF concrete hangar pad and surrounding asphalt apron pavement