Bringing together an experienced team of toxicologists and industrial hygiene practitioners from Canada and Southeast Asia, WSP carried out the HHRA in close collaboration with the client during the planning, study implementation and presentation to national regulators.
The HHRA framework was based on internationally accepted guidance such as the Health Canada Guidance on Human Health Preliminary Quantitative Risk Assessment and United States Environmental Protection Agency Integrated Risk Information System. The key objectives of the study were to assess whether fly ash by-products contained hazardous substances and assess the risks to human receptors. These objectives were achieved through a range of procedures in which we collaborated with the client to help them build an understanding of site practices needed for the assessment.
Upon review of monitoring reports available and an initial site reconnaissance, a sampling plan was prepared with a list of constituents of concern (COCs) based on commonly expected parameters (e.g. particulate matter, silica, metals, polyaromatic hydrocarbons) associated with fly ash exposure. The sampling approach included personal air monitoring of specific COCs, not only of the plant employees but also third-party hauling contractors who were primarily exposed in handling fly ash. Area monitoring of the fly ash units was also carried out to determine levels of certain COCs.
Based on the results of the study, we produced a risk assessment and made recommendations for managing human health risks, such as monitoring the truck loading area around the fly ash unit to maintain measured concentrations below regulatory limits and enhanced use of personal protection equipment. Our team's presence during the client’s fly ash management presentation to the regulators, one of the key steps required to obtain permit approval, supported the communication of the methodology and HHRA study results.
This work was performed by Golder professionals who joined WSP in an acquisition completed in 2021.