One of the most contentious areas of environmental management
relates to USTs and ASTs. Although some industrial tanks contain hazardous
materials, the vast majority of storage tanks (approximately 96% of USTs)
contain petroleum products. Federally, UST systems 110 gallons or greater
are regulated under Subtitle I of RCRA with a few exceptions. State and local
regulations vary around the country, but usually mirror the federal regulations.
Underground storage systems have been particularly problematic in contaminating the environment. Leaks tend to be below grade, out of sight, and are not detected for many years, thereby, causing wide scale soil and groundwater concerns. There are over a million active USTs in the United States and most of those installed prior to 1988 have had releases. Obviously, this is a large concern for UST owners, especially when considering the average UST remediation costs more than $50,000.
Our staff has worked on hundreds of UST sites throughout the United States conducting preliminary site evaluations, tank removals, soil and groundwater characterization studies, plume delineation, and groundwater modeling. When necessary, we have also designed remedial systems and made suggestions to revise the existing systems already in place. Due to the complexity of the fate and transport of contaminants, multiple technologies and combination of technologies are typically reviewed. Remedial technologies reviewed include; air sparging, soil vapor extraction, granular activated carbon, dual phase extraction (DPE), monitored natural attenuation (MNA), and overexcavation along with free product recovery. If requested, we have also prepared assurance fund reimbursement claims in numerous states.
Historically, ASTs have not caused the wide spread contamination
that USTs have, but several high profile ASTs have had catastrophic releases
over the years. Also, ASTs tend to be more of a safety concern since they
typically contain flammable and combustible liquids and have vehicular traffic
nearby. Since leaks can be detected rather quickly for aboveground tank systems,
the long-term impact is usually less than that encountered for UST systems.
The strategy for EPA’s
enforcement program for USTs seems to be replacement and continual monitoring
versus for ASTs which seems to be geared more for periodic monitoring and
contingency planning. Therefore, most of our services related to ASTs have
revolved around spill prevention with only occasional remedial investigations.
Services typically provided for ASTs are related to compliance with the Oil
Pollution Act (OPA) such as secondary containment design, tank integrity testing,
spill prevention control and countermeasure plan preparation, and spill contingency
plan preparation.
The types of materials that we have encountered in USTs and ASTs include; chlorinated solvents, mineral spirits, acetic acid, waste oil, gasoline, diesel fuel, fuel oil, vegetable oils, propane, PCBs, and various other forms of LNAPL/DNAPL. The wide variety of materials, geologic settings, and regulatory frameworks encountered by our staff has prepared us for virtually any situation that may arise relating to USTs or ASTs. Typical UST/AST services provided include:
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