Once contamination in exceedance of the applicable guidelines has been confirmed and sufficiently characterized, the area of concern can be either risk managed or remediated. We present clients with advantages, disadvantages and costs for each alternative and assist them in finding a solution tailored to their needs.
Risk Management & Mitigation
A Risk Management Plan is usually needed in order to characterize the environmental risks associated with the contamination and determine how to manage those risks in a way best suited to protect human and ecological receptors. We routinely develop Risk Management Plans for properties that schedule remediation activities to coincide with the site (re)development as well as for properties where a transformation mechanism (such as natural attenuation) is the main remediation strategy. Each plan is developed based on the characteristics of the site, expected contamination fate and behavior and the needs of the client. No two Risk Management Plans are the same.
If determined that the contamination presents an unacceptable risk and remediation is not an immediate viable option, an Exposure Control Program is recommended. This can be accomplished by creating barriers between source and receptors or by implementing administrative controls. For example, sub-floor vapour control systems designed to prevent vapour intrusion of volatile organic compounds are a common and relatively inexpensive mitigation solution.
While under a risk management or mitigation scenario the site does not obtain regulatory closure, this option is adequate when the remediation is delayed for a strategic reasons or the remediation is not feasible.
A remediation program may be required when unacceptable levels of contamination are encountered on a site. It is common that several remediation options are available for a site. Together with the client we analyze in detail the available options presenting the advantages and disadvantages of each one. Usually the preferred remedial approach is decided together with the client and technical, financial and logistical aspects of the program are discussed prior to the selection of the best solution. A Remedial Action Plan will be needed prior to undertaking the remediation program.
The Remedial Action Plan presents in detail the chosen remediation method, the steps needed prior to undertaking the work, describes the confirmatory sampling plan and develops a site-specific contingency plan. Sometimes the action plan needs to be reviewed and approved by the regulator prior to undertaking the work. If the remediation work has a limited scope the action plan is not a requirement.
In Alberta, underground fuel storage tanks that are no longer needed or have been out of service for 2 years must be removed from the ground. EDI personnel has organized, supervised and overlooked hundreds of underground storage tank removals as well as sampled and remediated the impacted soils around the tanks.
All storage tanks must be removed in accordance with provincial and federal regulation. The authority having jurisdiction must be notified prior to removal. If contamination is encountered during the tank removal Alberta Environment and Parks as well as the Fire Authority must be notified.
Significant technological advancements have been made in the environmental remediation field in the last decade resulting in new remediation methods available. However, with only 20-30 years of research and development, the remediation industry is still in the early stages. As the need for environmental remediation is gaining gradually more attention, the industry is going through rapid growth. The main drivers are regulatory requirements, lender’s requests, public awareness, emerging contaminants and others.
We do not prefer a certain remediation method and we believe that each site requires a specific clean-up based on the characteristics of the contamination and the needs of the client. We take into consideration a large range of remediation options from the straightforward ‘dig-and-dump’ approach to more technologically complex treatment methods that require in-house research such as bench tests or pilot tests. Each treatment method is thoroughly investigated based on the available literature as well as the most recent scientific information.
Once the remedial plan is developed EDI will coordinate the contractors needed to complete the remedial work and will supervise the day-to-day activities. In order to best serve our clients we employ specialized remediation contractors, when required. Our remediation budgets are developed as itemized comprehensive costs and include the follow-up monitoring (if needed).
Selecting the most appropriate remediation technique is sometimes difficult when dealing with emerging contaminants or unique site conditions. Older cleanup technologies are utilized in some cases extensively without questioning whether new methods would not be more beneficial. Ongoing research and site specific evaluation are essential in determining the best approach for a contaminated property. We have conducted significant research and have partnered with other Alberta stakeholders to find innovative solutions for impacted properties. To date we focused our study on:
In situ salt and metals remediation using electrokinetics
We achieved significant reductions in contaminant concentrations using in-situ electrokinetics. Targeted chemicals are salts and metals; research is still in the early stages for other contaminantns. Our remediation programs are designed in house based on each particular conceptual site model. All electrodes are constructed in house allowing us to keep the remediation cost low. Additionally, for some projects we are receiving assistance from our research partners so the client can get some reduction in cost on the monitoring portion of the project. As our waste storage facilities are being slowly replaced by recycling facilities, in-situ methods are expected to be utilized more in the future.
Enhanced pumping methods for organic and inorganic contaminants
Pump and treat methods have been utilized successfully in the past and they remain a recognized technology. The main limitation of the pump and treat method is the permeability and the radius of influence of the pumping well. We are utilizing a combination of methods to concentrate the contamination around the extraction well in an attempt to speed up the cleanup process and make the remediation system more efficient.
Disulfides remediation using a multi stage approach
We have successfully conducted bench tests and in-situ pilot testing focused on disulfides contamination. Using innovative injection techniques we managed to reduce the disulfide levels in groundwater.