2015 SMART Remediation Toronto – January 29, 2015

Joe Ricker, EarthCon Consultants, Inc.
Advances in Groundwater Plume Stability and Plume Diagnostic Evaluations
Bio | Abstract

Dr. Theresa Phillips, exp Services
Vapour Intrusion RA Methodology: A Comparison of Empirical vs Modeled (J&E) Soil Vapour and Indoor Air Concentrations
Bio | Abstract | Presentation

Vapour Intrusion RA Methodology: A Comparison of Empirical vs Modeled (J&E) Soil Vapour and Indoor Air Concentrations

The Johnson and Ettinger (J&E) model for vapour intrusion is heavily depended on by consultants in Ontario for the generation of risk-based Property-Specific Standards (PSS) intended for the filing of Records of Site Condition (RSCs) under Ontario Regulation 153/04. The model was also used by Ontario regulators to derive the current soil and ground water Standards for volatile organic compounds (VOCs) and is an integral part of the Tier 2 Modified Generic Risk Assessment (MGRA) model. However, the model is widely viewed as being highly conservative with respect to predictions of vapour intrusion risks. Therefore, we endeavored to validate the model and input parameters that are considered suitable for risk assessment by the MOE, using empirical data collected from several risk assessment sites in Ontario. We compared the predicted source vapour and indoor air concentrations of several VOCs, as modeled for a number of risk assessments, to actual measured soil vapour and/ or indoor air concentrations. Our results suggest that the model over-predicts indoor air concentrations by at least an order of magnitude, when used with soil data. Data for three chlorinated VOCs (tetrachloroethylene, trichloroethylene and vinyl chloride), measured at three sites, were evaluated. Modeled indoor air concentrations based on maximum ground water concentrations of the same VOCs, at the same sites, were less conservative but generally still overestimated the indoor air exposure concentrations. Over-predictions of vapour infiltration obtained using soil data are probably due to the MOE-mandated assumption that a single point source exceedance extends beneath the entire footprint of the building in question. Thus, estimates of the spacial extent of impacted areas and revised modeling results, for soil impacts, were also prepared for evaluation. In most cases, the presence of ground water contaminants was accompanied by concurrent soil impacts, which likely accounts for under-predictions of indoor air concentrations using ground water data alone. The results of our assessment also suggest that source vapour concentrations predicted by the J&E model are generally higher than actual soil gas measurements. Modeled source vapour concentrations of chlorinated VOCs (1,1-dichloroethylene, trichloroethylene, tetrachloroethylene) on one site, or petroleum hydrocarbons (benzene, toluene, xylenes) measured on a second site, in soil and/ or ground water, were consistently higher than measured soil vapour concentrations of the same parameters. It is our hope that comparisons such as these, of predicted values versus empirical data, will aid in future development of more appropriate models for vapour intrusion, to be used in the risk assessment of brownfield sites.

Jean Paré, Chemco inc.
Slow-Release Persulfate and MultiOx™ Cylinders for Passive, Long-Term, In-Situ Treatment of PHC Sites
Bio | Abstract | Presentation

Slow-Release Persulfate and MultiOx™ Cylinders for Passive, Long-Term, In-Situ Treatment of PHC Sites

Groundwater impacted with petroleum hydrocarbon contamination (e.g. benzene, toluene, ethylbenzene, xylene (BTEX), methyl-tert butyl alcohol (MTBE), and polycyclic aromatic hydrocarbons (PAH’s)) is common. In situ chemical oxidation using persulfate and permanganate, or combinations of persulfate and permanganate has been successfully as a treatment technology for the remediation of petroleum hydrocarbons and BTEX compounds. The application of Persulfate SR (Slow Release) ISCO reagent and MultiOx™ SR ISCO reagent cylinders are novel remedial approaches for the implementation that are sustainable low footprint, does not require the injection of liquids, and minimizes disruption of active facilities. This presentation will show case a series of bench-scale oxidation experiments were performed to (i) understand oxidant release rates from slow-release persulfate or MultiOx cylinders versus direct chemical injection, (ii) determine the persistence of oxidants in site soil, and (iii) determine the kinetic rate of contaminant degradation. Oxidant release rates from slow release oxidant cylinders were evaluated in a series of long-term 1-D column experiments. Soil oxidant demand was experimentally determined from a range of oxidant concentrations. Additionally, batch contaminant oxidation experiments were conducted in deionized water and soil materials to evaluate the potential of natural activation mechanisms. Kinetic models were used to describe the contaminant oxidation rates and regression models were developed to quantify the release of oxidants from the cylinders. Finally, 1-D column experiments were conducted to demonstrate BTEX/MTBE oxidation efficiency from slow-release persulfate and MultiOx cylinders. Based on the lab work above, a conceptual framework was developed that incorporated (i) oxidant release from the cylinders, (ii) soil oxidant demand rates, and (iii) contaminant oxidation kinetics. Results from these experiments demonstrate that the oxidant released from the cylinders is sufficient to overcome the soil oxidant demand, and can effectively degrade petroleum hydrocarbon contaminants in situ. The utilization of slow release persulfate or MultiOx cylinders can provide a simple, long-term and cost-effective approach for remediating petroleum hydrocarbon contamination in the subsurface. The cylinders can be easily emplaced in the subsurface using direct-push technology or suspended in wells for easy recharge. There is great potential to combine the slow release oxidant cylinders with other technologies such as biological remediation or other mass removal strategies (e.g. excavation, SVE) for accelerated and more efficient site remediation.

Evan Cox, Geosyntec Consultants
Case Study: Full-Scale Electrokinetic-Enhanced Bioremediation (EK-BIO) of a PCE DNAPL Source Area in Clay Till
Bio | Abstract | Presentation

Case Study: Full-Scale Electrokinetic-Enhanced Bioremediation (EK-BIO) of a PCE DNAPL Source Area in Clay Till

The success of in-situ remediation technologies requires effective and uniform delivery of remediation reagents through the target treatment area. Traditional amendment delivery techniques based on hydraulic advection mechanisms are often faced with limitations in areas with low-permeability materials and/or highly heterogeneous geology. Transport of ionic substances, such as lactate, in an electric field is relatively independent of hydraulic properties and fluid flow. Therefore, electrokinetic-enhanced amendment delivery represents an innovative solution allowing effective in-situ remediation in areas where permeability is limited and heterogeneous. In 2011 a field pilot test was carried out at the Skuldelev site, Denmark to assess the ability of the novel EK-BIO technology to treat PCE DNAPL source material in clay till with interbedded deposits of sand. The EK-BIO pilot test demonstrated the transport and distribution of amendments (lactate and microbial culture KB-1™) through clay soils in the target area. Results from groundwater and clay soil sampling showed significant reductive dechlorination of PCE to cisDCE, VC and ethene coupled with significant levels of dechlorinating microorganisms (Dhc with vcrA), indicating that PCE dechlorination in clay soil was achieved by EK-BIO with KB-1™ bioaugmentation. Based on the successful pilot test, full-scale remediation was implemented. Full-scale EK-BIO of a PCE source area at was initiated in December 2012. The treatment zone, addressed by a network of 15 electrode wells, covers an area of 100 m2 to a maximum depth of 10 m bgl. The overall area is divided into two sub-areas, which are treated in alternating stages, each for a period of three months. The polarity of the electrodes is changed to alter the current directions and electric field orientations in alternating stages in order to optimize the EK transport efficiency and to achieve treatment of the entire target zone for remediation. Performance monitoring comprises monthly water sampling for TOC and field measurements, as well as quarterly water sampling for complete characterization of contaminant composition and degradation processes. In addition, soil sampling was also performed at the end of select stages of operation to assess treatment in clay materials. The results from the first two years of EK-BIO operation will be presented. At present, 5 stages (approximately 20 months) of operation and monitoring have been completed with very encouraging results. Electron donor and Dhc have been distributed throughout the treatment area, and complete reductive dechlorination of PCE to ethene has been well established, with the degree of dechlorination continuing to increase. Orders of magnitude increases of Dhc have been observed between clay soil samples collected before remediation and following one year of EK-BIO. Soil sampling data support the groundwater monitoring data and confirm that EK-BIO implementation has achieved active reductive dechlorination treatment within low-permeability clay materials. Successful implementation of this EK technology will broaden the applicability of various in-situ remediation technologies including in situ bioremediation and in situ chemical oxidation.

Maureen Dooley, REGENESIS
Sorption Coupled with Enhanced Biodegradation to Treat PHC and VOC Groundwater Contamination
Bio | Abstract | Presentation

Laura Jones, Golder Associates
Case Study: Using Laser Induced Fluorescence (LIF) to Establish a Monitoring Well Network for a Mobile LNAPL Plume Near a Surface Water Body
Bio | Abstract | Presentation

Case Study: Using Laser Induced Fluorescence (LIF) to Establish a Monitoring Well Network for a Mobile LNAPL Plume Near a Surface Water Body

The former Michigan Avenue Landfill (now Canatara Park) was used by the City of Sarnia for disposal of municipal waste between approximately 1930 and 1967. Between approximately 1930 and 1944, oily waste was reportedly disposed of at the Site from one of the local refineries. This waste material was reportedly a by-product of a process that used clay to remove colour impurities during the production of automobile lubricating oil. In 1997, light non-aqueous phase liquid (LNAPL) was discovered to be discharging to the southwest shore of Lake Chipican, north of the former landfill. In response, temporary measures were taken by the City to contain and collect the oil film at the lake. In 2000, remedial measures were developed to mitigate the discharges from former Michigan Avenue Landfill including installation of a 70-metre-long sheet-pile barrier wall along the south shore of Lake Chipican and installation of two oil recovery wells south of the barrier wall. An annual monitoring program commenced in 2000, to detect LNAPL at monitoring locations prior to potential migration to Lake Chipican. During routine monitoring in October 2011, LNAPL was detected in a sentry well located near the west end of the barrier wall which prompted additional remedial measures. Since LNAPL was discovered in a sentry well, a subsurface investigation was undertaken to determine the current extent of LNAPL in the vicinity of Lake Chipican. The subsurface investigation used Laser Induced Fluorescence (LIF) to delineate the extent of the LNAPL plume and to determine locations for additional monitoring wells to provide advance warning of plume migration prior to encountering sensitive receptors. LIF uses a built-in laser to emit short pulses of light of a certain wavelength range. Polycyclic aromatic hydrocarbons (PAHs), present in the automobile lubricating oil, fluoresce when excited by light of a known wavelength and emit light of a specific wavelength range. In April 2012 and April 2013, an LIF investigation was completed at 49 locations and monitoring wells were installed at 9 locations near Lake Chipican and associated surface water bodies to provide advanced warning of LNAPL plume migration. These additional wells were incorporated into the annual groundwater monitoring program and have been included as trigger wells in the Trigger and Contingency Plan for the former Landfill. Since start of the LIF investigation program, additional LNAPL migration has been discovered based on the network of monitoring wells installed and results of the LIF investigations. Additional LIF investigation is planned for Fall 2014, the results of which will be included in the platform presentation.