Phase II Environmental Site Assessment (ESA) and Characterization
What is Phase II (ESA) and Characterization?
Phase II Environmental Site Assessment (ESA) and Characterization are critical stages in evaluating the presence, extent, and risk of environmental contamination on a property. They follow a Phase I ESA, which identifies potential environmental concerns (recognized environmental conditions, or RECs) through records review, interviews, and site reconnaissance.
What Is a Phase II Environmental Site Assessment?
A Phase II ESA is an intrusive investigation that involves sampling and laboratory testing of soil, groundwater, surface water, and sometimes vapor or building materials to determine whether contamination exists and to what extent.
It is designed to confirm or refute the potential environmental risks identified in the Phase I ESA.
Key Components of Phase II Site Assessment
1. Site-Specific Sampling Plan
- Developed based on Phase I findings, historical land use, and potential contaminant pathways.
- May target:
- Fuel storage areas
- Chemical handling zones
- Former landfills or lagoons
- Drainage paths or stained soils
2. Drilling and Sampling
- Soil sampling using hand augers, direct-push, or rotary drilling rigs
- Groundwater monitoring wells installed for water table evaluation
- Soil vapor sampling (if vapor intrusion risk is suspected)
- Surface water/sediment samples if applicable
3. Laboratory Analysis
- Commonly analyzed contaminants:
- Petroleum hydrocarbons (TPH, BTEX)
- Metals (arsenic, lead, chromium, etc.)
- Volatile organic compounds (VOCs)
- Semivolatile organics (PAHs, PCBs)
- Pesticides and herbicides
- Samples tested at certified labs using EPA or provincial methods
4. Hydrogeological Characterization
- Water level measurements
- Permeability testing (slug tests)
- Aquifer depth and flow direction determination
5. Site Characterization
- Data interpretation to define:
- Contaminant plumes
- Depth to contamination
- Source-pathway-receptor linkages
- Exposure risk potential
6. Reporting and Recommendations
- Data compiled into a Phase II ESA report that includes:
- Figures/maps (borehole logs, contaminant plumes)
- Lab results
- Comparison to regulatory standards (e.g., CCME, EPA, provincial Tier 1/2 guidelines)
- Risk evaluation
- Next steps: no further action, additional delineation, or remediation
Objectives of Phase II ESA
| Objective | Description |
| Confirm contamination | Validate whether potential concerns from Phase I are real |
| Define contaminant types | Identify specific chemicals (e.g., hydrocarbons, metals, solvents) |
| Assess contamination extent | Map vertical and lateral spread in soil, groundwater, or air |
| Determine health/environmental risks | Support regulatory compliance and risk-based decision making |
| Support remediation planning | Provide input for cleanup strategies or site redevelopment |
When Is a Phase II ESA Required
| Trigger | Description |
| Suspected contamination | Evidence of historical spills, dumping, or chemical storage |
| Due diligence in property transactions | Banks or buyers request environmental clearance |
| Regulatory enforcement | Orders from environment ministries or protection agencies |
| Brownfield redevelopment | Redevelopment of industrial or commercial sites |
| Permitting and approvals | Required by municipalities, environmental boards, or indigenous consultations |
Difference Between Phase I and Phase II
| Attribute | Phase I ESA | Phase II ESA |
| Type | Non-intrusive | Intrusive (field work required) |
| Purpose | Identify potential RECs | Confirm and characterize contamination |
| Method | Records review, interviews, site visit | Sampling and lab analysis |
| Outcome | Need for further investigation | Contamination confirmation and mapping |
Summary
| Component | Description |
| Definition | A subsurface investigation to assess the presence and extent of contamination |
| Typical Activities | Drilling, soil/water sampling, vapor testing, lab analysis |
| Contaminants Tested | Hydrocarbons, metals, VOCs, PAHs, PCBs, pesticides |
| Used In | Environmental due diligence, remediation planning, regulatory compliance |
| Deliverables | Data tables, borehole logs, contaminant maps, risk assessments, regulatory comparison |
Phase II Environmental Site Assessment (ESA) and Characterization are critical stages in evaluating the presence, extent, and risk of environmental contamination on a property. They follow a Phase I ESA, which identifies potential environmental concerns (recognized environmental conditions, or RECs) through records review, interviews, and site reconnaissance.