LM Consulting

Current technical consultant assisting potentially responsible parties (PRPs) in differentiating contamination from multiple sources. Chemical fingerprinting was used to differentiate PAHs and dioxins/furans in sediment sourced from various sources including: former chemical manufacturers, a former MGP site, a former creosote plant, petroleum releases, and urban stormwater runoff. Historical document review and bathymetric studies were used to document redistribution of contamination due to physical processes such as shoreline development, downstream sediment transport, dredging, and other anthropogenic activities. Prepared multiple technical reports which have been submitted to regulatory agencies and allocators, providing scientific basis for quantitative separation of comingled contamination attributable to distinct sources.

Dr. McWilliams worked closely with the client and their counsel to limit the investigation required to respond to a unilateral order from the Oregon Department of Environmental Quality (DEQ) to investigate sediment sites contaminated with polychlorinated biphenyl (PCB) and other compounds upstream of the Portland Harbor Superfund site. She designed and implemented a sampling program that successfully demonstrated the absence of residual contamination around the client’s existing sediment cap and identified a City-owned stormwater outfall as a primary historical and ongoing contamination source. A detailed review of historical information in the stormwater drainage basin identified sources of PCBs that were not attributable to the client. She negotiated with the DEQ to perform a streamlined risk assessment, which significantly reduced costs and shortened the time required to complete the RI report. She was lead author of the RI report which provided the basis for negotiations regarding a sustainable remediation strategy.

Through her work with several projects, Dr. McWilliams significantly reduced the scope of required remediation both by successfully differentiating PAHs attributable to manufactured gas plants (MGPs) from other PAH sources, and by demonstrating the limited toxicity of highly-degraded MGP residuals in aquatic environments. Through multiple technical presentations for regulators, she has successfully communicated the results, which were then used to design efficient sediment remedial actions. Specific accomplishments include using 3-Dimensional Conceptual Site Models (CSMs) to describe site conditions, the nature and extent of contaminants, their stability, and potential pathways and receptors and designing innovative site investigations that addressed regulatory requirements, determined actual environmental risk using empirical evidence, identifying possible interim actions to mitigate immediate risks, and obtaining the proper information needed to prepare remedial design and address constructability factors. She also assisted her clients in communicating and collaborating with multiple stakeholders both with and outside their organizations.

Dr. McWilliams developed and oversaw a multimedia sampling program that evaluated potential residual impacts after a focused dredging action removed PCB contaminated sediment. In order to demonstrate that monitored natural remediation would be sufficient to complete the remediation, she oversaw the collection and analysis of water, sediment, clams, crayfish, sculpin, and smallmouth bass that provided the data required for ecological and human health risk assessments. She used a statistical sampling approach to compare the local conditions to those in a downstream reference area to demonstrate that PCB concentrations in lower trophic-level media were decreasing to ambient levels, and that the concentrations in fish should soon follow. She was lead author of a comprehensive RI report that evaluated potential in-water and upland risks and recommended focused follow-up investigation/source control for the uplands and development of a monitoring program for the river.