1,2,3-trichloropropane (TCP) was used historically as a paint and varnish remover, a cleaning and degreasing agent, a manufacturing solvent, and was a common component of soil fumigants previously used widely in agriculture. TCP is characteristically mobile in the subsurface and resistant to natural attenuation, and its persistence has resulted in wide-spread impacts to water supply systems. The U.S. Environmental Protection Agency (EPA) is evaluating TCP as part of the Third Unregulated Contaminant Monitoring Rule (UCMR3), which is used to determine whether a contaminant will be subject to future regulation, while individual states have or are in the process of developing regulatory levels for TCP that are as low as 0.0005 micrograms per liter.

TCP is mobile in the subsurface and resistant to natural attenuation. Compared to more halogenated compounds, TCP is less likely to sorb to solid material or partition into the vapour phase. Remediation options for TCP are limited, particularly at current and anticipated future regulatory levels. Treating groundwater with low concentrations of TCP presents unique remedial challenges. Remedial technologies that have been evaluated or implemented at scales ranging from laboratory treatability studies to full-scale field implementation include in-situ bioremediation (ISBR), in-situ chemical reduction (ISCR), and in-situ chemical oxidation (ISCO).

One innovative treatment process that produces promising rates of TCP degradation is ISCR with zero-valent zinc (ZVZ). This presentation will summarize results from laboratory tests, small-scale pilot and field scale pilot studies and performance monitoring designed to collect data to demonstrate and validate the use of ZVZ to promote abiotic ISCR of TCP in groundwater. In addition, data is being collected to develop performance metrics evaluating ZVZ delivery and treatment efficacy, engineering design, regulatory approval and cost benefit analysis. This work is being conducted in conjunction with academic partners at the Oregon Health & Science University with funding from the US Navy Environmental Sustainability Development to Integration Program (NESDI) and an Environmental Security Technology Certification Program (ESTCP) grant.

Current approaches for remediating TCP in groundwater are infeasible or cost prohibitive. Since TCP has been identified as an emerging contaminant by the federal government, successful development and transition of ZVZ technology can help lead to expedited facility clean-up and closure. In addition, ZVZ technology may be more broadly applicable to the wider family of lesser chlorinated hydrocarbons, a particularly recalcitrant class of compounds that is challenging to remediate.

Suzanne O’Hara, Senior Hydrogeologist, Geosyntec Consultants, Inc.
Suzanne O’Hara is a hydrogeologist with more than 20 years experience. She uses her experience to support clients through her focus on conceptual site model (CSM) development and remediation of groundwater and soil using innovative and more conventional technologies.

Her remediation expertise includes enhanced in-situ bioremediation, in-situ chemical oxidization and reduction, STAR thermal remediation, passive treatment using zero valent metals, and the treatment of PCBs in building materials.

Suzanne has directed, managed, or provided technical support for projects ranging from overall strategy development, site investigation, long term monitoring, monitoring and remedial design, costing and implementation, contaminant fate and transport, and CSM development.

Esquimalt Harbour has historically been used for log booming, log storage and wood mill operations over the last 70 years. These activities have lead to the accumulation of wood waste deposits in the subtidal area of the Harbour. Over 300,000 m3 of wood waste are present in over 200 hectares in Esquimalt Harbour. As wood waste decomposes, it creates a biological oxygen demand in sediments that, in an excessive amount, can reduce or eliminate oxygenated zones. This can lead to a build-up of compounds such as sulphides, ammonia, and methane, which are toxic to many benthic organisms in the concentrations correlated with human-caused wood waste. Wood waste leaches and/or degrades into toxic compounds such as phenols, benzoic acid, benzyl alcohol, terpenes, and tropolones, several of which have been determined through either laboratory or in situ testing to be toxic to aquatic life.

Public Services and Procurement Canada, on behalf of the Department of National Defence, is conducting risk management studies for the sediments within Esquimalt Harbour containing wood waste deposits from historical activities. The work includes use of an innovative passive porewater sampling technique to quantify dissolved sulphide using the diffusive-gradient-in-thin-films (DGT) method to quickly and accurately measure porewater sulphide concentrations. The DGT method is based on the reaction of sulphide with silver iodide and is becoming increasingly common as a reliable in-situ technique for quantifying sulphide levels in sediment porewater. This presentation describes the DGT testing methods using deployment times ranging from 30 minutes to 24 hours. Measured concentrations ranged from less than 1 mg/L to over 200 mg/L, with most concentrations between 20 and 40 mg/L. Bioassay testing was also conducted using the bivalve larval development test to assess site-specific toxicity for a range of wood debris and porewater sulphide concentrations.

Remediation of wood waste impacted sediments has historically involved expensive remedies such as dredging and capping. However, treatment amendments have the potential to oxidize or immobilize porewater sulphide. An innovative bench-scale testing program was conducted to assess the effectiveness of sand cover mixed with a range of treatment amendments to reduce bioavailable porewater sulphide concentrations in sediments containing wood wastes. Treatment amendments include mineral-based materials such as iron oxides, manganese oxides, and iron carbonates. Vertical profiles of redox zonation and porewater sulphide were measured with DGTs in the amended cover and underlying wood waste sediments to assess the effectiveness of the reactive amendments. The testing program supports the use of a variety of treatment amendments that would result in far more cost-effective remedial solutions than dredging or capping in this large wood waste area. The results are being used to design an in-situ field pilot study.

Dan Berlin, Principal Scientist, Anchor QEA, LLC
Dan Berlin is a Principal Scientist at Anchor QEA, LLC and has more than 18 years of professional experience managing sediment remediation projects. He holds a Master’s degree in Environmental Management and specializes in designing sediment investigation studies and managing remedial options analysis, and design and clean-up of large, complex sediment remediation projects in the United States and Canada.

The production, testing, storage and disposal of munitions in support of national defense and mission readiness has resulted in releases of munitions constituents (MC) to the environment at training ranges, ammunition plants, production facilities, and storage and disposal areas. Investigation and remediation techniques have been developed, and are continuing to be developed, to cost-effectively mitigate or remedy environmental impacts. These efforts can be complicated at sites where unexploded ordnance (UXO) and munitions and explosives of concern (MEC) are known to be present, or unexpectedly encountered during field activities. Understanding typical release mechanisms, commonly encountered contaminants, up-to-date investigation and remediation techniques, and appropriate planning and hazard mitigation techniques at these sites is critical for safe, successful and cost-effective site clean-up. This presentation will address these issues, and will present several case studies for complex sites where remediation of emerging contaminants such as perchlorate, RDX, chlorinated solvents, and 1,4-dioxane are present in soil and groundwater.

Evan Cox, Senior Principal Remediation Scientist, Geosyntec Consultants International, Inc.
Evan Cox is a Senior Principal Remediation Scientist at Geosyntec Consultants International, Inc. with more than 28 years of demonstrated experience in the development and application of innovative in-situ remediation technologies for energetic and chlorinated chemicals in subsurface environments. He works with private sector interests and government research programs to develop innovative in-situ treatment technologies, and to demonstrate and validate their use at field scale for widespread commercial use. He has pioneered many of the biological treatment techniques for perchlorate in soil and groundwater, having worked at more than forty perchlorate sites worldwide. As part of his in-situ remediation research, development, and implementation work, he has authored over 50 professional publications and articles regarding the degradation of hazardous contaminants in subsurface environments, and has co-authored multiple guidance documents and educational courses for Environmental Protection Agencies.