What Do You Understand by Preliminary Site Investigation?

Environmental Site Assessment

Environmental assessments are usually conducted to obtain information about the subject property and analyze its historical uses. These steps are taken to ensure that there is no potential for contamination. The assessments are also conducted to minimize any risks to human health or the environment. This article focuses on on-site inspection, precisely what a Preliminary Site Investigation (PSI) is. A PSI gives an initial understanding of the characteristic sites and can identify the potential risks involved. PSI’s are the same as Environmental Site Assessments(ESA). However, PSI’s are more common in British Columbia, whereas ESA’s are more common in Alberta. PSI’s generally comprise of two stages:

A Stage I Preliminary Site Investigation (PSI) goes hand in hand with a Phase I Environmental Site Assessment (ESA). Stage I primarily involves a historical evaluation to determine if previous or current operations have contaminated the site. This stage mainly requires desk study, which refers to obtaining information based on research with no physical investigations. The scope includes a record review of the subject site and its neighbouring properties. Any past contaminations can still have lasting effects on the site.

Furthermore, all documents related to the property, including previous assessments, should also be reviewed. The next step, as with any Phase 1 ESA, is site reconnaissance. This involves a physical inspection of the site by conducting a walkover survey looking for actual and future hazards. Surveying techniques can be utilized to develop boundaries on the site. An on-site inspection assesses if the soil, groundwater, or any vapours have any contaminants in them. An experienced assessor will determine this by checking if the amount of substances present exceed what is expected from standards. If the assessor has cause for concern, the Areas of Potential Environmental Concerns (APEC) and the Potential Contaminants of Concern (PCOC) should be clearly identified. Multiple site reconnaissance visits may need to be carried out due to time constraints or if an area was inaccessible during the first visit. While on-site, interviews should be carried out with professionals who have extensive knowledge about the property. These include but are not limited to current and previous owners, managers, government officials, and employees who have worked there long enough. This stage puts emphasis on the preliminary in PSI. Therefore, no subsurface investigations or sampling is required at this stage.

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Also Read: Phase 1 Or 2 Environmental Site Assessment: How to Plan It?

If there is cause for concern and the assessor believes that there may be a chance of contamination, a Phase II ESA should be initiated. The purpose of the Stage II Preliminary Site Investigation is to find a general location and extent of contamination that was predicted in Stage I. This investigation tends to be more intrusive and includes drilling, excavation, or any other form of testing to collect samples that will be sent for laboratory analysis. Site investigations also identify underlying geology, hydrogeology, physical hazards, and gases such as methane. All other relevant environmental media must be sampled. Depending on the type of contamination predicted, other intrusive or non-intrusive methods of investigation may also be required. The laboratory analysis will focus on aspects such as delineating and characterizing the hazardous substances. Once the sample testing results are obtained, the assessor can conclude with evidence whether contamination exists or not. A Stage II PSI is essentially pursued in order to confirm the existence of the contaminants that were predicted as an APEC in Stage 1. In the case that contamination exists, i.e., the amount of substance violates the Provincial standard, the groundwater Drinking Water standards or affects the Aquatic life, then a remediation process should be developed. For example, if there is groundwater contamination, then continuous groundwater monitoring should be set up on-site. Along with that, the neighbouring properties should conduct subsurface investigations to determine how far the contamination may have travelled and what risks they pose to their site. A boundary must be developed for the contamination, and urgent actions have to be taken to stop the spread.

Most provincial governments in Canada provide some form of a checklist that assessors can follow during the preliminary site investigations. These can be found online or can be attained directly from the provincial office. Generally, the final report will include a brief summary of the investigation. The summary would include aspects such as the thoroughness with which the reviews were conducted if there was a need for additional investigations, the level of certainty, and which standards were followed. Then, the report should include sections dedicated to the statement of objectives, the sampling program and all associated rationales, the data collected and evaluated, and any other recommendations.

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Pinaaz Rahman

Project Coordinator-Environmentalist at prycoglobal
Pinaaz is a Chemical Engineering graduate who has years of experience conducting Environmental Site Assessments. She studied at University of Alberta and brings a fresh perspective on projects. Pinaaz has an impressive background in process analysis/design and is our lead Environmentalist.
Pinaaz Rahman

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