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Introduction To Site Closure




Site closure is a milestone achieved when the remaining contamination in the soil, surface water, groundwater, or air meets a risk or cleanup threshold determined not to pose a threat to human health or the environment. Determining the end point of a corrective action at a leaking underground storage tank (LUST) site may involve reaching a targeted concentration for certain contaminants or reducing the risk of contamination to a specific threshold. Risk-based decision-making (RBDM) criteria are applied more and more frequently to enable tank owners and operators to achieve a quicker and more cost-effective site closure. RBDM allows cleanup to be performed to a risk level that reflects the future use of the site rather than a generic, potentially more stringent cleanup level that is difficult to justify in the context of certain site uses.

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Risk Characterization And Closure

Depending on the jurisdiction overseeing the remedial activity, completion of corrective action at a LUST site may be based on the remaining and foreseeable risk to human health and the environment. Risk assessors or toxicologists are often engaged to evaluate human risks based on the potential inhalation, skin, or ingestion exposures from the contamination. These risk characterizations often analyze the potential carcinogenic threats of petroleum constituents to pregnant women and small children. Environmental risks are evaluated based on the impact to vertebrates and invertebrates, plants, and their respective habitats. Once a characterization adequately evaluates the risk of all contaminants of concern and their potential exposures, a risk-based decision can be made regarding closure of a LUST site.

In cases when site closure is not based on risk, there are conservative thresholds established by government agencies that must be met for site closure. These thresholds are calculated levels based on generally accepted safety standards.

More On Risk Characterization And Closure [Show/Hide]

UST Technical Compendium Category 5: Closure
EPA UST Technical Compendium that includes clarifications of notifications and requirements on UST closure.

Exit Strategy–Seeing the Forest Beyond The Trees - Second in a Series of Remediation Process Optimization Advanced Topics (18 pp, 533K, About PDF) Exit EPA disclaimer
Interstate Technology & Regulatory Council (ITRC) technology overview on the basics and advantages of a performance-based exit strategy as a component of performance-based management of the environmental remediation process.

API Recommended Practice 1604, "Closure of Underground Petroleum Storage Tanks" Exit EPA disclaimer
American Petroleum Institute recommended procedures for the closure in place, removal, storage, and off-site disposal of underground storage tank systems that have contained flammable or combustible fluids.

How Do You Close Tanks?
EPA site that discusses the basics of UST tank closure, including temporary and permanent closure.

Closing Underground Storage Tanks: Brief Facts (2 pp, 28K, About PDF)
EPA brochure on the basics of UST closure.

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Maintenance And Abandonment Of Sampling Points

Groundwater and vapor intrusion sampling points are often maintained after site closure to allow owners, operators, or government entities an opportunity to confirm and re-evaluate the decision to close a LUST site. Groundwater monitoring wells must be properly maintained at the ground surface to ensure that surface petroleum releases or contaminated stormwater do not flow into the well boring and contaminate a clean groundwater resource.

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Maintenance and Decommissioning Requirements for Monitoring Wells Associated With Hydrogeologic Investigations (3 pp, 126K, About PDF) Exit EPA disclaimer
New Hampshire Department of Environmental Services fact sheet on monitoring well maintenance requirements, decommissioning a well, and monitoring well abandonment procedure.

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Documentation And Reporting

Site closure requirements vary significantly among implementing agencies. Final closure actions generally must be documented and filed with the appropriate government agency. Documentation typically includes narrative descriptions of the release, a full summary of assessment, and corrective actions, maps, plans, summaries of field and laboratory data, a data quality assessment, and a risk characterization. Closure reports are public records that remain open for inspection. Some jurisdictions require legal notices in the local newspaper or certified notifications to adjoining property owners when the cleanup process has been completed.

Many governmental agencies are now allowing documents and reports to be filed electronically through Web-based systems. In addition to saving time and paper, these systems allow interested parties to quickly review and download documentation to their personal electronic devices or computers.

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Closure and Corrective Action Exit EPA disclaimer
Michigan Department of Natural Resources and Environment Waste and Hazardous Materials Division (WHMD) home page on closure and corrective action with information on how to comply with relevant Michigan requirements.

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Certification Of Closure

Once the reviewing agency approves the final documentation and reporting from a cleanup, a final approval may be certified in writing. This written approval documents a liability endpoint that can be used for lending or conveyancing purposes.

Increasingly, many implementing agencies are relying on qualified professionals to certify that a permanent closure has been achieved. These individuals are usually licensed, and their certification of closure states that the cleanup endpoints, which are either established by the implementing agency or carefully evaluated based upon risk to public health or the environment (i.e., RBDM), have been met. This certification may be subject to screening and audit at the discretion of the government agency.

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Ecological Revitalization: Turning Contaminated Properties Into Community Assets (83 pp, 4.4M, About PDF) Exit EPA disclaimer
EPA CLU-IN overview of ecological revitalization that includes technical considerations, planning and process considerations, and case studies.

Reusing Cleaned Up Petroleum Sites
EPA page with examples of how petroleum brownfield sites can be reused, reuse success stories, and information on the redevelopment process.

Regulations Pertaining To Underground Storage Tanks (40 CFR Part 280): Subpart G – Out-of-Service UST Systems and Closure
Federal regulations on UST closure; 280.74 pertains to closure records.

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