Many people know that a Phase One Environmental Site Assessment (ESA) can lead to the recommendation of verifying a site’s condition by testing the soil and/or groundwater quality in a Phase Two ESA.
But what happens after a Phase Two ESA?
If the results come back favorable with no further recommended investigations, you send off your final report with a Letter or Reliance to your lender or other stakeholders with confidence that environmental risk on the site has been assessed.
If there is evidence of contamination (otherwise known as environmental impacts) in your soil and/or groundwater, the Phase Two ESA report conclusions may come with a recommendation for a supplemental sampling program to delineate the extents of the impact.
What Is Impact Delineation and Why is it Necessary?
Delineation is the process of defining the horizontal and vertical boundaries of contamination found during a Phase Two ESA, and may involve additional drilling, test-pitting, or indoor air quality testing.
Think of it as drawing a 3D “bubble” around contamination to understand:
- Where it starts
- Where it ends
- How deep it goes
- Whether it’s moving with groundwater
- Whether it poses a risk to occupants, neighbours, municipal systems, or source water protection zones
You cannot design an effective Remedial Action Plan (RAP) without knowing the size, shape and movement of the contamination. Delineation provides the following:
- The necessary data to select the optimal potential remedial approach
- Allows estimations of various remedial cost options
- Avoids an inflated remediation action plan, or worse
- Avoids the potential for an ineffective remediation plan that doesn’t solve the problem or leaves future hidden impacts and costs undefined
Why You Might Need More Boreholes (Even After a Phase Two)
A Phase Two ESA is designed to identify whether potential contaminants are present, in general areas of potential environmental concern (APECs), not to map them fully. Once contaminated points are detected, delineation aims to define the impact zone size, shape and potential movement of contaminants below the surface of the site.
1. Determine the full extent of impact
Phase Two ESA results often show if contamination exists — but they don’t tell you if it’s:
- Isolated
- Widespread
- Shallow
- Deep
- Moving
- Increasing or decreasing with distance
2. Determine the direction of groundwater flow
Groundwater moves across a site in a “gradient.” Contaminants dissolved in groundwater move with it. To understand movement, delineation wells are installed:
- Upgradient (to determine if the source is onsite or offsite)
- Transgradient (to determine width of impact)
- Downgradient (to determine if contaminants are potentially leaving the property)
3. Build an informed dataset
For many sites, delineation data is technical requirement for:
- RSC filing
- Risk Assessment
- Lender requirements
- Redevelopment and permitting
- Remedial plan design
Good News: We Can Use Your Existing Data
Delineation doesn’t mean starting over. If you’ve already begun investigating your site, and delineation is your next step, we can typically leverage your Phase One ESA, Phase Two ESA, historical well data, and any previous work completed to help with recommendations for the next steps in your site goals.
By using existing data to guide the plan, we can:
- Reduce the number of additional delineating wells and / or samples needed
- Focus only on areas and contaminants that have been conclusively identified to be present/impacted
- Identify optimal and alternate paths forward
- Minimize cost, disruption and delays
What Delineation Typically Involves
Depending on your site, delineation may include:
- Installation of new monitoring wells
- Soil sampling (at surface and/or at water table interface)
- Groundwater resampling
- On-site testing and followed by laboratory verification
- Contaminant plume mapping
- Updated ESA reporting
- Development of a site-specific Remedial Action Plan (RAP)
Speak with our experts about your site-specific details today
We can design a full program or review your existing data first and design a targeted, cost-effective delineation plan tailored to your needs.
The Value of Delineation to Your Project
While delineation comes with a cost, the value of accurately delineating a project is:
- Confidence in overall project timelines, budgets and outcomes
- Addressing the full potential contamination impact zone, to mitigate future issues like leaching, back-diffusion and/or off-site migration
- Not overpaying for excessive remediation
- Mitigating liability and risk to site owners, lenders, and occupants
Let AEL Help
Our team has completed delineation programs across Ontario for industrial, commercial, residential, institutional and government lands, for contaminants ranging from petroleum hydrocarbons (gasoline), to PCBs, to dry cleaning solvents (chlorinated solvents) and other varied contaminants in soil and groundwater. AEL delineation programs and remediations have enabled successful lending on and redevelopment of sites with clay, sand and fractured bedrock subsurfaces from less than 1 acre of impact to over 10 acres in size.
Whether you’re:
- Responding to unexpected exceedances
- Preparing for an RSC
- Buying/Selling property
- Conducting due diligence
- Seeking a second opinion
What Our Customers Have To Say
AEL worked with us to assess, remediate, and file RSCs for a number of our sites. They used innovative technology in efficient ways, reducing the cost and working within our time frames. Their team is technically strong, and also able to communicate well.
Vince Polsoni, Manager of Station Sustainment
PowerStream Inc.