Environmental site assessment – Phase 1
Basically, a Phase 1 environmental site assessment aims to locate any danger of potential or real contamination on a property. The Phase 1 refers to the general principles of the CSA Z768-01 norm. It consists of gathering information on the site and includes the following steps :
- Historical data collection;
- Site visit;
- Interviews and information access;
- Evaluation of the environmental risks;
- Production of a Report.
Environmental site assessment – Phase 2
If a potential or real contamination risk is found during Phase 1 of the environmental site assessment, it is highly recommended to proceed with Phase 2. The purpose of this assessment is to either confirm the presence of the contaminants or to demonstrate the absence of pollution. The goals of a preliminary characterisation are:
- to precise the contaminant type;
- to identify the soil types, the stratigraphic conditions and the characteristics of the groundwater;
- to target the contaminated sectors;
- to evaluate the extent of the contamination.
Environmental site assessment – Phase 3
As a result of the work done during Phase 2, we may conclude that the realisation of a thorough characterisation is advocated. In order to plan adequately the rehabilitation work needed on the site, as well as its cost, it is often necessary to redefine the environmental issue that was brought up by Phase 2. The goals of a thorough characterisation are:
- to complete the information obtained by Phase 2;
- to precisely determine the nature and the extent of the contamination;
- to classify the ground waters so as to identify their utilization;
- to precise the dynamic of the groundwater contamination issue;
- to evaluate the impacts of the contamination.
To evaluate the impacts of the contamination
The owner of a site that has exceeded the acceptable contamination criteria or norms may be forced by his financial institution or by a potential buyer to proceed a soil or groundwater remediation work for his property. Also, the presence of a contamination is always perceived as a limiting factor for a site’s value. Prior to any site rehabilitation, it may be necessary to remove all contamination sources (underground tanks, etc.). Afterwards, the intervention strategy for the corrective measures will result directly from the historical studies, the previous characterisations, as well as the budget and the time allowed to fulfill the work.
Based on these facts, the first preoccupation of the owner willing to rehabilitate their site will be to choose among the management choices proposed by the MDDEP. For example:
- the decontamination using the generic criteria of utilization;
- the decontamination using the risk evaluation procedure;
- the set up of contamination containment, control and follow up procedure (cover up);
- the set up of restrictive usages defined by the risk evaluation procedure.
The risk evaluation or containment procedures must be approved by the Ministère du Développement durable, de l’Environnement et des Parcs (MDDEP). The decontamination via generic criteria of utilization or via norms can be carried out in two different ways, “ex-situ” or “in-situ”.
- The method usually chosen by short on time owners is the one called “ex situ”, which comes to excavating the soils and transporting them outside the site, to be treated or to be disposed in an authorized site. The operation is fast but requires the use of heavy machinery and a lot of transport.
- If the owner has more time or the excavation appears to be technically difficult and/or of a too big extent, an “in situ” treatment may be realised on the property. These treatments are carried out on the soils in place, with minimal disturbance for the surroundings. The “in situ” treatments often use biologic technologies involving less equipment but requiring more time than “ex situ” treatments. This type of treatment however requires a very good knowledge of the environment (thorough characterisation of the soils and the groundwater) so as to obtain a satisfying result.
Underground Storage Tank Removal
The existence of an underground storage tank constitutes a contamination risk for the soils of a property.
During the Phase 1 of the environmental evaluation, the discovery of an underground tank, potential or real, past or present, often leads to a preliminary characterisation. When the presence of an underground petrol equipment is discovered, the tank has to be removed and the disassembly material has to be handled according to the applicable standards by an authorized contractor. The steps for the removal of an underground storage tank are as follow:
- Pumping of the liquid waste remaining inside the tank;
- Cleaning and disassembly of the petroleum equipment and disposition of the disassembly materials;
- Transportation of dangerous substances;
- Recycling of oils and fuel residues;
- Sampling of the surrounding soils;
- Evaluation of the corrective measures that have to be applied if the analytic results of the soil samples collected during the previous step displays values that exceed the generic criteria or the standards.
The generic criteria for contaminated soil (A, B and C) were established in 1998 in the Politique de protection des sols et de réhabilitation des terrains contaminés (or PPSRTC) of the ministère du Développement durable, de l’Environnement et des Parcs du Québec (MDDEPQ) in order to allow the interpretation of the analytic results obtained during the soils characterisation.
|Classe A||Background levels for inorganic parameters and analytical detection limit for organic parameters.The detection limit is defined as the minimum concentration that can be quantified using an analytical method of defined reliability.|
|Classe A-B||Maximum acceptable limit for residential, recreational and institutional sites. Commercial sites located in a residential district are also included.
Institutional use includes hospitals, schools and day-care centres. Recreational use includes a large number of possible cases presenting various levels of sensitivity. Thus, sensitive uses such as playgrounds must be managed according to level B, while recreational uses considered less sensitive, such as bicycle paths, may be associated with level C.
|Classe B-C||Maximum acceptable limit for commercial sites not located in a residential area, and for industrial sites.|
|Classe C+||Decontamination in an authorized treatment site is required and management according to the cleanup level reached. If the preceding option is impractical, final disposal in an authorized secure landfill is required.|
|Classe D+||According to the RESC (Règlement sur l’enfouissement des sols contaminés) the soil must be treated prior to their landfilling.|