Landfills and Other Solid Waste Management Facilities
We have often assessed potential hazards to human health and the environment due to chemical releases from landfills and other facilities that process municipal solid waste (MSW).
Depending on their design, location, and operations, landfills can release contaminants to ambient air and/or surrounding waters, as can transfer stations, recycling facilities, composting operations, and other waste management facilities. Assessing risks to human health and the environment involves (1) identification and characterization of contaminant releases, (2) estimation of levels of exposure to contaminants through various pathways, and (3) evaluation of the toxicological significance of such exposure. Depending on community concerns, exposures associated with waste transport, truck traffic, and/or nuisance odors may also need to be evaluated.
Sample Projects
Odor Evaluations
We have evaluated health hazards of nuisance odors from many landfills. In some of these situations, odors arose from using sulfur-rich fines from processed construction and demolition (C&D) debris as daily cover material. Formerly, this was thought to be a beneficial use of this material, but anaerobic decay of the combined MSW and C&D fines resulted in the formation of unacceptable concentrations of hydrogen sulfide (H2S) and other reduced sulfur compounds in landfill gas. Fugitive emissions of landfill gas, unavoidable to some degree even with efficient collection systems, can be annoying to downwind neighbors. One example of our work in this area is an evaluation of potential health effects from odorous emissions from Bristol Landfill.[PDF]
PFAS Emissions from Landfill Gas Combustion
One of us (SGZ) collaborated with a University of Vermont research team to investigate emissions of per- and poly- fluoroalkyl substances (PFAS) to air from landfill gas (LFG) combustion. Inlet sampling of the LFG focused on the volatile fluorotelomer alcohols (FTOHs) that dominate PFAS in LFG. Low concentrations of stable PFAS were found in stack emission measurements made with U.S. EPA Method OTM-45. The rates of OTM-45 stack emissions from the energy recovery engine and flare were found to be 1.9% and 0.4%, respectively, of the FTOH inlet rates, indicating limited (if any) conversion of FTOHs to stable PFAS during combustion.
Plainville (MA) Landfill
We developed a human health and environmental risk characterization for the Plainville Landfill as part of a Comprehensive Site Assessment under Massachusetts solid waste regulations. Risks were evaluated from contaminants in groundwater and surface water due to leachate release. 1,4-Dioxane was identified as a marker chemical, and plume discharge to a nearby lake required a detailed ecological risk assessment, including sampling of fish to determine uptake rates of manganese and other metals. Significant odors from landfill gas emissions were assessed through one of the first real-time ambient monitoring studies of hydrogen sulfide coupled with source-gas analyses. Risk assessment results were used as part of a third-party study of cancer incidence rates in the local population.
Chicopee Landfill
We developed a risk assessment of a proposed expansion of the Chicopee (MA) Sanitary Landfill to satisfy the Massachusetts Department of Environmental Protection's requirement to demonstrate the project would not significantly increase risks to public health. The study is representative of a number of Cumulative/Facility Impact Assessments designed to evaluate risks from the operation of solid waste management facilities. The U.S. EPA's LandGem model predictions of gas generation were combined with a measured landfill gas composition profile to estimate potential emissions of over thirty Hazardous Air Pollutants (HAPs) identified in landfill gas. Air dispersion modeling was then applied to project incremental concentrations of HAPs in air at locations in the landfill vicinity. Incremental cancer and non-cancer risks were estimated by combining modeled HAP concentrations with toxicity data, and risk levels were found to be lower than target levels. The potential cumulative effects of other air pollution sources were qualitatively assessed by identifying emissions from nearby industries and facilities, and environmental monitoring data on the landfill site were reviewed to identify whether contaminants in groundwater might present risks to local citizens.
MSW-derived compost
We developed numerical guidelines for various chemicals contained in compost produced from yard waste and municipal solid waste at the Nantucket (MA) Co-Compost Facility. Guidelines were designed to allow various beneficial uses of the compost, including residential landscaping and home gardening, considering potential avenues of exposure such as incidental ingestion and dermal contact. Of the contaminant levels measured in compost samples, various phthalates were sometimes encountered at levels exceeding risk-based standards. Potential risks were mitigated through process changes to limit contaminant concentrations in compost.
Evaluating PFAS Impacts to Groundwater from an LFG-to-RNG Facility
One of us (SGZ) assisted the developer of a Renewable Natural Gas (RNG) facility in obtaining an air permit. The RNG process uses landfill gas (LFG) to produce pipeline quality natural gas. One of the regulatory concerns centered on per- and poly- fluoroalkyl substances (PFAS), which are known to be present as an impurity in the landfill gas feed. Could the deposition of PFAS air emissions to the ground contribute to an exceedance of groundwater standards? Most of the PFAS vented from the process will likely be destroyed by the facility's thermal oxidizer. Relevant data from landfill gas flare testing was used along with fate-and-transport models to demonstrate that the potential release from air emissions and deposition of PFAS would not significantly contribute to PFAS concentrations in local soils and groundwater.