MERLEX ENGINEERING LTD.
Consulting Geotechnical Engineers

In order to properly assess the environmental conditions present at a site, a multitude of factors must be considered. The scope of the study can range from a Phase I ESA or preliminary site assessment to a Phase III ESA which includes recomendations and design of a site remediation process. Environmental site assessment work is currently defined within the industry as comprising of three distinct phases of activity, each with a specific set of objectives and methodologies:

The Phase I ESA is outlined in CSA Standard Z768. The purpose of the study is to identify, by a systematic process, actual or potential site contamination. This includes a review of all available site records, a physical investigation of the prevailing site conditions and interviews with persons knowledgeable to the site. A Phase I ESA does not involve the investigative procedures of sampling, analysing, and measuring unless enhancements are agreed on between the Client and the Assessor. The study is site specific and is designed to screen the site for evidence of potential environmental problems and advise the client as to need for specific follow-up work.

The Phase II ESA is performed if the Phase I ESA reveals potential environmental risks or gaps in information that cause significant concern. This secondary study involves quantitative site investigation(s) using intrusive sampling and anlayses of various media to characterize the specific type and extent of designated potential contaminants. Several subphases of increasingly site specific sampling may be required as the study progresses and analytical results are recieved. The quantitative data results form the basis for determining the most appropriate and cost effective method for site remediation.

ESA Phase III The ESA Phase III involves the remediation of site soils, groundwater and/or structures to an acceptable state of environmental compliance. A few of the possible remediation practices include material removal or encapsulation, in-situ soil cleansing or bio-remediation. The Phase III ESA also includes follow-up verification studies for proof of compliance.

"Gasoline Contaminated Soil: Remediation by Removal"

Geo-environmental engineering addresses the condition of both soil and groundwater environments through geotechnical drilling and the impact contaminants have on these materials. The environmental health of a site is of major concern to property owners/developers and financial institutions involved in property transactions.

At several of the sites where Phase I and subsequent Phase II Environmental Site Assessments have been carried out, contamination of the soil and/or groundwater were encountered. A detailed investigation of soil and groundwater sampling using in-house facilities was carried out to delineate the approximately magnitude of the environmental liability. In the past where hydrocarbon contamination (gasoline, diesel, furnace oil, jet fuel, lubricants, etc.) have been encountered as a main contaminant, a process of "dig" and "haul" (i.e. removal of contaminated soil for transport to an approved disposal site) were considered cost efficient. However, this approach becomes less attractive where (a) development in the area limits access (i.e. under and between structures) and (b) cost increase for tippage and transport fees. As such, the need to reclaim and restore the environmental condition of the site versus transporting the problem off site becomes more attractive. As such, our firm has developed expertise with various techniques of treating contaminants on site, either in-place (in-situ) or through removal, treatment, and replacement. In several recent projects, we are treating the groundwater and soil utilizing an on-site bioreactor system and subsequently incorporating vapour extraction and soil washing (through recharging the contaminated area via an infiltration gallery). This treatment for hydrocarbon contamination has proved very successful from both the technical (i.e. rate of treatment, etc.) and cost point of view, since we have negated the high monthly cost of filter replacement (GAC, TM100, etc.) which have been used in the past on "pump and treat" systems.