At XCG, we understand how to best assess the risks associated with managing older solid waste disposal sites and their impact on the surrounding environment. XCG’s experts take the time to assess each client site on a case-by-case basis to establish site performance and provide a focused approach to successfully manage solid waste landfills of all types and history. Here are three interesting projects we are proud to have worked on.
Vapour Intrusion – Alberta
The Montfort Landfill is a historic waste disposal site located within the City of Red Deer that operated until 1969. After site closure, a residential development was built adjacent to the site. This presented the potential for landfill gases to impact the neighbouring homes and residents so XCG was asked to undertake a Vapour Intrusion Assessment to determine the current condition of the landfill and to delineate any impact or risk to the neighbouring properties. A monitoring program was completed that included the installation of monitoring infrastructure (groundwater wells and soil vapour probes), and sampling for groundwater, soil vapour, and indoor air quality. Site specific soil vapour guidelines were established for the site and the risk of the landfill to nearby receptors was established. The results led to recommendations that included an annual focused monitoring program on the site which will ensure the continued safety of the residents.
Located within the Regional District of North Okanagan, the Armstrong Spallumcheen Recycling and Disposal Facility includes a landfill which accepts municipal solid waste from the surrounding communities. The facility historically utilized a poplar plantation to manage leachate from the lined portion of the landfill. This stand of trees, however, was nearing the end of its effective lifespan. At the same time, questions arose regarding the performance of the site’s attenuation zone and whether there was risk to down-gradient groundwater receptors from the unlined portion of the landfill. XCG undertook a Hydrogeological Performance Assessment to evaluate the effectiveness of the attenuation zone and identify any gaps in the hydrogeological knowledgebase for the site. Based on the results of this assessment, XCG reviewed a number of leachate management options and chose a combined pond evaporation and phytoremediation strategy. This preferred option was based on site-specific feasibility, potential environmental impacts, existing landfill structure, proximity to municipal infrastructure, regulatory environment and capital/operational and maintenance cost considerations. The new site strategy has low long-term capital and operational costs, simple operation and will be sustainable for both the active and post-closure life of the landfill.
The Pender Harbour Landfill in the Sunshine Coast Regional District had been in operation since the 1960s and was scheduled for closure in 2015. The natural attenuation landfill had been retrofitted with numerous environmental controls over the years, including leachate collection piping and a treatment wetland. To design an effective final closure for the landfill, XCG conducted a landfill performance assessment that included the attenuation zone. XCG reviewed all historic studies as well as the site design, compliance points and potential receptors. A conceptual site model was developed that addressed topography, drainage, climate, geology and hydrogeology of the site. The model showed that the site was in compliance and performing well due to a well-functioning balance of hydrogeological, climate and drainage conditions with existing environmental controls. The final closure works were designed to support and integrate this balance and ensure continued, post-closure, site compliance.
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