water protection

treatment, supply and conservation


Environmental Site Assessment

Environmental site assessments (ESAs) are carried out to determine the environmental quality of soil and groundwater at a site. These assessments are conducted at residential, commercial, agricultural, and industrial property sites. However, a site assessment does not imply that the site is contaminated or has been exposed to contamination. ESAs are classified into three main categories:

Phase I Environmental Site Assessments

A Phase I ESA is conducted to affirm or refute the association of environmental liabilities with a property prior to business transactions (e.g., purchasing a property) or even for undeveloped land parcels. A Phase I ESA may also be conducted at a site to ensure that there is no environmental liability associated with it as a precondition of using it as collateral to secure a loan. It is advisable to conduct ESAs for properties located close to environmentally sensitive businesses, such as dry cleaners and gas stations, prior to a purchase transaction.

In a Phase I ESA, MEK will conduct a thorough review of various documents, including reports and records associated with the property, such as:

  • a)  Historical building permits;
  • b)  Fire insurance plan/maps;
  • c)  City directory reviews;
  • d)  Government/provincial databases;
  • e)  Topographic maps of the area;
  • f)   Aerial photographs;
  • g)  Local hydrogeological conditions; and
  • h)  Available environmental databases.

These in-house reviews are followed by a series of interviews with the owners and residents of the area (if possible) and a thorough inspection of the site and adjoining ones. The ultimate goal of a Phase I ESA is to confirm the likely presence of hazardous substances in the soil and shallow groundwater at the site.

MEK will provide a detailed report clearly specifying the scope of the assessment, findings, conclusions, and recommendations for the client. In particular, the report will clearly articulate the likely existence and potential locations of hazardous substances, if any, together with a statement regarding the qualification of the assessors.

Phase II Environmental Site Assessments

A Phase II ESA is always a follow-up on a Phase I ESA and is based on the outcome of and recommendations contained in the Phase I ESA Report. Phase II ESAs are carried out if the results of the Phase I ESA assessment indicate the potential for the existence of hazardous substances in the soil and/or groundwater at the site. The main thrust of a Phase II ESA is to identify the type and concentrations of hazardous substances and their distribution within the shallow soil and groundwater at the site and to use this information to develop a remediation plan. The hazardous contaminants commonly found during these assessments include petroleum hydrocarbons, persistent organic compounds, and inorganics. The type and degree of contamination is usually dependent on historical site activities.

Phase II ESAs will always entail intrusive sampling and may include trenching and drilling of boreholes and installation of monitoring wells to sample soil and groundwater for laboratory analysis to determine concentrations of the various contaminants. A major component of a Phase II ESA is hydrogeological studies to determine the hydrogeologic properties and other characteristics of the aquifer at the site. This information can be very valuable for delineating the extent of contaminant spreading and for remediation planning.

If laboratory analysis indicates significant levels or exceedances above recommended threshold values, then additional characterization may be required to determine the horizontal and vertical extent of the contaminant plume. Information obtained from the Phase II ESA can be used to develop the conceptual site model, which will ultimately become the planning tool for the remediation of the site.

Phase III Environmental Site Assessments

A Phase III ESA is conducted if a Phase II ESA investigation indicates significant contamination at the site and therefore the need for additional assessments to clarify the extent of the contamination at the site or if clean-up and thus further characterization, risk assessment, or remediation is warranted. Usually, under a Phase III ESA, remediation must proceed to the point where contaminant concentrations fall below federal/provincial mandates or until all the contaminants have been removed from the property.

The MEK team has completed numerous and diverse Phase I, II, and III ESAs at residential, commercial, agricultural, and industrial property sites and in accordance with the Canadian Standard Association Standards Z768-01, the American Society for Testing and Material (ASTM) Standard E-1527-13, and other federal and provincial regulations and protocols.