Abstract
Stormwater Management Ponds (SWMPs) provide water quality control by allowing contaminated sediment to settle out of the water column into pond basins, where they accumulate over time. Sediment removal is routinely required in order to maintain water quantity control and quality improvement efficiencies. Excavated/dredged sediments are managed in accordance with environmental regulation requirements. Typical waste disposal practices can be extremely expensive and environmentally unsustainable as compared to beneficial reuse alternatives. In 2005, Dr. Francine Kelly-Hooper began the ongoing Canada-wide SWMP sediment chemistry survey, which has grown to include 425 samples collected from 140 residential SWMPs. The study results identified Total Petroleum Hydrocarbons (TPHs) and Polycyclic Aromatic Hydrocarbons (PAHs) as the leading contaminants to trigger waste disposal requirements. In 2016, Francine began collaborating with the Minnesota Pollution Control Agency and the US Geologic Service on a source identification study. Weight-of-evidence included sediment chemistry data, GC-FID chromatograms and Chemical Mass Balance modelling, which identified asphalt as the primary TPH source and coal tar sealants as the primary PAH source. Since that time, several plant growth trials, earthworm toxicity testing and field scale studies have demonstrated that bioavailability and leachability risks were much lower than the bulk soil concentrations had indicated. The combined study results have led to risk based beneficial reuse of contaminated sediments, as cost effective and environmentally sustainable alternatives to waste disposal practices.
Dr. Francine Kelly-Hooper is the GHD Canadian Sediment Lead and a Petroleum Hydrocarbon Subject Matter Expert (SME), with over 20 years of experience in the government and private sectors. Francine completed her Ph.D. at the University of Waterloo in 2013, where she developed the Biogenic Interference Calculation (BIC) for identifying true versus false petroleum hydrocarbon sources in soils and sediments. Her 26-year Canada-wide stormwater management pond (SWMP) sediment chemistry survey has compiled contaminant source identifications for over 140 residential SWMPs. Francine and her GHD team continue to collaborate with international governments on the development of risk based beneficial reuse alternatives to expensive and environmentally unsustainable waste disposal practices.