Hazardous materials and environmental projects are rarely completely straightforward: that’s what makes them so exciting! But managing the complications along the way (within budget and project timeline) is always an interesting process. Join us for an exploration of such a project at an Ontario school board site.
Introduction
In 2018, an Ontario school board engaged ECOH to perform environmental and hazardous materials assessments of school buildings at one of their sites. These buildings were to be decommissioned and eventually demolished. The buildings were constructed in a time when asbestos and other hazardous materials were often used. As such, a pre-demolition designated substances survey (DSS) was required.
Additionally, based on the age of the site buildings and visually identified pipes (e.g. fill and vent pipes) on the site, ECOH deemed an underground storage tank (UST) was likely present, or had been present in the past. ECOH’s environmental team planned a comprehensive geophysical survey of the site in the area of the suspected UST. The scope was created: let the project begin!
What are Designated Substances?
Designated substances are those chemical agents prescribed as such by O. Reg. 490/09 and include the following eleven:
- Acrylonitrile.
- Arsenic.
- Asbestos.
- Benzene.
- Coke oven emissions.
- Ethylene oxide.
- Isocyanates.
- Lead.
- Mercury.
- Silica.
- Vinyl chloride.
Many of these substances were historically applied throughout building materials, with asbestos and lead being the most commonly identified in our surveys. A pre-demolition DSS is a detailed assessment of all accessible hazardous building materials and is required under Section 30 of Ontario’s Occupational Health and Safety Act (OHSA). This section states that, prior to tendering the work, an owner must identify designated substances on the project and provide a list to contractors bidding on the work.
Such work is also required under Ontario Regulation (O. Reg.) 278/05, Regulation respecting Asbestos on Construction Projects and in Buildings and Repair Operations, which controls the disturbance of asbestos materials on construction projects. O. Reg. 347/90 is also a guiding regulation, controlling the disposal of asbestos waste. There are lots of potential for health and safety risks with exposure to these substances, therefore, lots of regulations and guidelines to control and advise on the assessment and removal of such materials.
Project Beginnings
It was a straightforward beginning: ECOH scientists performed a DSS and identified asbestos, lead, mercury, PCBs and silica in building materials throughout the site building. These materials would all need to be safely removed following regulatory requirements and industry best practices prior to demolition. The comprehensive list of designated substances, along with thorough recommendations, not only helped our client meet OHSA obligations, but plan for a demolition that protected people and the planet.
ECOH also completed an initial geophysical survey and utility mapping at the site. A geophysical survey is a comprehensive study of the earth and subsurface conditions to gather information about its properties and any buried item/s. The objective of this survey was to identify any anomalies beneath the ground that could represent:
- An underground storage tank (UST),
- Pipes or utilities associated with an UST, and/or
- Fill material (soil) which may be indicative of a former UST excavation.
ECOH retained a private utility locating company to support with the geophysical survey. They used a ground-penetrating radar (GPR) scanning device to detect any anomalies. The survey identified an anomaly within the scanned area, likely associated with either the remnants of a former UST, or soil used to fill the cavity left by a previously removed UST. Now what?
A Clear-Cut Beginning to Project Complexities
As per the requirements of the applicable Codes and Regulations, ECOH recommended that an intrusive investigation be conducted to verify the presence of the suspected UST. A test pit excavation was completed within the suspect area at the Site. And, as suspected, soil contaminated with petroleum hydrocarbons (PHCs) was revealed, most likely associated with the historical UST. But no buried storage tank! The presence of contaminated soil and the fill and vent pipes provided enough information to infer an UST had been present, and removed in the past. No information was made available for ECOH’s review to confirm if the former UST was removed in accordance with applicable codes and regulations, but the presence of contaminated soil led us to suspect that it was not.
Test pit excavations on the site
As the scope and complexity of the project began to expand due to these stage 1 findings, a borehole drilling program was recommended (stage 2). The purpose of this drilling was to determine the specific extent of the contaminated soil on the Site and, if there was potential for contaminants to migrate off-site through groundwater flow. A broad estimation of the contaminated soil that would require excavation could be made at this stage, however, a borehole drilling program would help delineate more precisely and potentially save excavation costs down the road. And so, stage 2 of the project was born.
Borehole drilling for further delineation
Health Impacts of Contaminated Soil
If soil contaminated by fuel oil or solvents (PHCs etc.) remains in place, these highly mobile contaminants can potentially migrate off-site via groundwater flow. Also, if the contaminated soil remains and buildings are constructed on top, vapour intrusion can occur. Vapour intrusion is when volatile chemicals in contaminated soil or groundwater migrate into the air spaces of overlying buildings. This process can lead to the accumulation of hazardous vapors within indoor environments, posing health risks to occupants (Love Canal, anyone?) Exposure to certain types of contaminants (such as PHCs) is associated with an increased risk of developing cancer. Detrimental health effects of continued exposure to such contaminants can also include:
- Nervous system damage,
- Hormone function disruption,
- Headaches,
- Eye, skin and lung irritation,
- Nausea, and
- Fatigue.
Removing contaminated soil is a regulatory requirement for good reason!
The Cost of Clean-Up
It is vital to thoroughly understand the characteristics of contaminants, groundwater flow, soil, environmental project management and the regulatory requirements of such projects. Just as important, though, is a detailed and systematic site assessment and expert remediation planning and oversight. Without these factors, soil remediation may be imprecise, and budget estimations can be vastly inflated. Expenses, however, are not just financial and legal, but can easily extend into costs to human and environmental health.
ECOH took a two-stage approach to investigate the soil and groundwater impacts at the site. While two stages are more costly to implement than one, the 2nd stage allowed for accurate delineation to inform a more precise remediation plan. If the estimated volume of soil requiring remediation after the first assessment stage had been removed, the costs would have been far greater. The two-stage, detailed approach meant soil volume could be accurately calculated and therefore reduced by 50% from initial estimates. This meant less budget uncertainty for the client, and significant cost savings over the long term.
Overcoming Challenges
Ex-situ remediation is the process of removing contaminated soil from the site for treatment or disposal at a licensed receiving facility. This process presents several challenges which can impact project timeliness, costs and overall effectiveness. Some of these challenges included:
- Ensuring the health and safety of all on-site personnel through varying weather conditions and project tasks (e.g., working around open excavation),
- Handling and managing large volumes of contaminated soil for off-site disposal,
- Soil disposal regulations,
- Managing groundwater infiltration into the excavation site throughout the project,
- Limitations of weather, particularly freezing and snowy conditions,
- Contractor scheduling constraints,
- Budget limitations, and more.
Overcoming challenges effectively is a key component to managing such environmental and hazardous materials projects. ECOH was able to pivot and solve all issues to assist the client with achieving their goals and maintain regulatory compliance. The entire remediation project was completed on time and within the estimated budget.
Excavation following the removal of contaminated soil
Conclusion
Environmental projects are rarely straightforward. Historic dumping, improper or partial removal of soil and groundwater contaminants, or literal ‘burying of the problem’, has resulted in a plethora of legacy issues beneath our feet. It is vital to understand the area’s history, geophysical properties, characterization and the distribution of contaminants, and regulatory context to efficiently and effectively remediate these legacy issues. This knowledge enables well-informed decisions and the implementation of more cost-effective remedial strategies, no matter the project complications.
