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Environmental Investigation for Closure of Sludge Monofill Area

Keene, New Hampshire

Services: Environmental Investigation, Solid Waste
Clients Served: Government

The New Hampshire Department of Environmental Services (NHDES) is requiring the City of Keene, NH to formally close a sludge monofill area at the former Rose Lane Wastewater Treatment Plant (WWTP) site. Loureiro was contracted to evaluate potential closure alternatives and provide the city with a better understanding of the benefits and limitations associated with capping in-place versus excavation with off-site disposal. Building upon the efforts of previous studies, Loureiro implemented two subsurface investigations to provide more definition of the limits, volume, and chemical characteristics of the sludge. The evaluation involved coordination with both the NHDES and the Environmental Protection Agency (EPA).

The investigations included drilling and sludge sampling. Loureiro also implemented a groundwater assessment program. Initially, Loureiro completed an assessment of 23 borings to characterize the vertical and horizontal limits of the sludge. Analytical characterization of the sludge revealed elevated concentrations of polychlorinated biphenyls (PCBs). Loureiro then performed a comprehensive investigation of the PCBs to determine the extents and maximum concentrations. Using a 30-foot by 30-foot sampling grid, samples of the sludge was collected every two feet totaling 80 samples. Samples were analyzed using the soxhlet extraction method and EPA method 8082 for PCBs.

Loureiro utilized the sludge and groundwater sample results and its experience with landfill closures to provide strong technical justification to NHDES and EPA for the in-place capping alternative to close the sludge monofill.

NHDES and EPA concurred with Loureiro’s findings and indicated that an in-place capping solution could be used to close the sludge monofill.


  • Complex regulatory environment involving overlapping jurisdictions
  • Comprehensive investigation of PCB concentrations in sludge material
  • Comprehensive cost-benefit analysis for proposed closure alternatives of capping in-place and offsite disposal