Challenge
The Town of Montague’s former municipal burn dump operated from the 1930s through the 1970s and was ordered closed by the Massachusetts Department of Environmental Protection (DEP) in 1982. An inadequate soil cap and groundwater contamination affecting Randall Brook remained. To fund a DEP-compliant closure, the Town contracted to install a photovoltaic (PV) facility atop the landfill cover system. During construction, additional solid waste was observed in areas north and south of the proposed landfill cap, potentially affecting solar array construction.
Solution
GZA prepared a design to extend the landfill cap to encompass the southern pond landfill area (cap in-place) and redesign the pond and associated stormwater conveyance systems. GZA’s design concept included placing a geomembrane liner over the additional solid waste encountered in the southern waste area, which included the entire pond area. The stormwater pond was redesigned to include a sand filter with a lined underdrain and new outlet structure. As part of the southern pond redesign, an underdrain system was required to ensure the pond drains and maintains its hydraulic capacity after storm events. GZA also prepared a design to extend the landfill cap extending to cover the additional area of waste located to the north of the existing landfill cover design (cap in-place). As part of the design, the landfill cover system extension grading was modified to will conform with the minimum slope requirements of the MassDEP Landfill Technical Guidance Manual (1997) and to allow the installation of the PV facility.
Benefit
GZA was able to redesign the landfill closure system and associated stormwater management system in accordance with DEP criteria, which allowed the client to complete its development and installation of a solar array system on a closed landfill. The redesigned landfill closure system allowed the Town of Montague to properly close the municipal landfill and fund the project through the installation of a PV facility.
