A description of the UST removal process follows.
1. Fire permit and inspection: A fire permit is obtained from the municipality, and an inspection of the removed tank is scheduled in advance of its removal. The permit is valid for 90 days after which it must be extended if the project is incomplete. In order for the permit to be closed successfully, all procedural requirements must be met.
2. Uncover and clean the tank: An excavator is used to uncover the top of the tank, a hole is cut into the top of the tank, and any contents are removed and disposed of according to Ministry of Environment regulations. A vacuum pump system designed to handle flammable liquids is used to remove residual liquids, solids, or sludge. The UST is cleaned thoroughly. Documentation of the disposal of UST contents is provided by the contractor.
3. Tank removal and disposition: An excavator is used to pull the tank from the ground and it is trucked to an authorized recycling depot. The thorough vacuum-pumping and cleaning ensures the tank is deemed non-hazardous. Documentation of proper disposal of a UST is provided by the contractor.
4. Soil sampling and analysis: To demonstrate the site meets Ministry of Environment ("MOE") standards, a minimum of one sample must be taken from each sidewall and the base of excavation of the tank nest; five samples in total. The samples must be transported to a certified laboratory under chain of custody protocol.
The excavation is then backfilled with clean soils. Samples are analyzed for extractable hydrocarbons (EPH) and poly-aromatic hydrocarbons (PAH); other analyses may be required depending on the site.
If the samples do not meet MOE standards, remediation must occur (in some cases it may be deferred). Remediation options include the excavation and removal of soil (ex situ remediation), or in situ remediation where an agent is injected or applied to remediate the soil of EPH and PAH contamination.
The number of samples that are taken initially may be limited if contamination is obvious. In this case, more excavation of contaminated soils will occur before the cost of sampling the entire tank nest is incurred.
When remediation is complete, further samples are taken to demonstrate the UST meets all environmental standards established by the Ministry of the Environment.
5. Reporting: A closure report is written to document the project and site status. The report includes a narrative of the removal process, sampling procedures and data, a site map depicting the UST and sample locations, copies of laboratory analysis, chain of custodies, disposal documentation, and a UST destruction certificate. The report is delivered to the client and the municipality, and the work is reported to the Ministry of Environment.
Ventus reports include a professional stamp administered by the Applied Science Technologists and Technicians of BC required for approval of UST removal reports within the City of Vancouver.
In Situ Remediation
Underground Storage Tank
In situ remediation may enable commercial properties to operate during the remediation process, and, in some cases, may be less expensive than ex situ remediation.
Stage 1, Stage 2, Detailed Site Investigations, and Screening Level Risk Assessments: Real estate transactions may require environmental information about a site. A Stage 1 Preliminary Site Investigation, a Stage 1 PSI, may be required to provide historical environmental information about a site. If a site has been used for purposes that could cause contamination a Stage 2 PSI is then completed to ascertain if the site has, indeed, been contaminated. A Detailed Site Investigation, a DSI, is completed to fully outline onsite contamination. A Screening Level Risk Assessment or SLRA may be required to ascertain concentrations of soil vapours for volatile contaminants and to access the exposure scenario of these vapours. Ventus Consulting can complete these projects in accordance with Ministry of Environment standards.
Groundwater Flow (Hydrogeology) and Contaminant Sourcing: Groundwater flow analysis can be used to determine the direction from which contamination has originated. Groundwater flow maps can demonstrate groundwater flow direction, velocity, water table gradient, and other parameters.
Soil Vapours: Soil vapours work is part of Screening Level Risk Assessment (SLRA) as vapours containing hydrocarbons or other harmful substances can migrate into buildings through utility corridors and other pathways. Soil vapour wells are installed after soils and groundwater concentrations are determined. A sample pump is used to pump soil vapour through a thermodesorption tube (TD) which is analysed at a certified lab. If soil vapour concentrations are above the applicable concentrations Ventus Consulting can remediate through passive venting, active vapour extraction or by remediating the source of the contamination.
The process relies on a combination of chemical oxidation and bio-remediation: the chemical oxidization is fast-acting, which the bioremediation process works over 2 years and fully remediates the soil after the chemical oxidization is complete.
Chemical oxidization uses a half-redox reaction that results in a loss of electrons to change contaminants into harmless compounds through the introduction of strong chemical oxidizers directly into the contamination. The chemical oxidizers quickly remediate numerous organic compounds some of which are resistant to natural degradation.
Bioremediation uses organisms to destroy contaminants in soil and water by adding microorganisms or nutrients to accelerate the natural biodegradation process. The bioremediation process used most often by Ventus Consulting introduces a bacterial oxidant that provides an oxygen source that continues to remediate soils over 2 years.
In-situ remediation is usually applied through a liquid injection method, where nutrients and chemical oxidizers are fed into contaminated soil via wells to reduce the concentrations of targeted contaminants to applicable standards. The number of wells and the volume of product that are required is calculated based on levels of contamination, volume of soils, and distribution.
Ventus Consulting Inc. is a full-service soils, groundwater, and soil-vapor environmental consulting firm
specializing in Underground Storage Tank ('UST') removal projects, and in situ remediation.
Underground storage tank projects typically involve the removal of an underground oil storage tank and the testing of soil from the tank nest from which it was removed. Increasingly this work is required by municipalities in order for development permits to be issued, by banks to eliminate risks, and in real estate transactions as well.
UST removal projects are subject to provincial regulations issued by the Ministry of Environment as well as by municipal regulations. While projects vary due to individual site circumstances, all must conform to provincial and municipal requirements.
The excavation and removal of contaminated soils, ex situ remediation, is the most common approach to remediation but it is not always the most cost-effective solution. When contaminated soils are inaccessible, or when minimal disruption of the surface is required, in situ remediation may be used. Examples of in situ remediation scenarios include:
- contamination under a building, road, or other permanent structure
- contamination that has migrated offsite
- contamination under or around valued trees
The in-situ remediation process used by Ventus Consulting remediates soils to applicable standards in 6-8 weeks.
Ventus Consulting has the in-house expertise and experience to deliver a services related to ground water, soils, and soil vapour.
Call us to discuss your project requirements.
Other services include:
Dry Cleaner, Gas Station, or Industrial Site Remediation: Dry cleaning fluid, tetrachloroethylene (perchloroethylene), contamination can occur on dry cleaners, and other types of industrial sites. Gas stations may experience gasoline, oil, or diesel fuel spills and leaks. Ventus Consulting can remediate sites using ex situ methods, removal for offsite disposal and remediation, or in situ methods, onsite remediation using chemical oxidants and bacterial agents.