Costs of remediating underground storage tank leaks exceed benefits

The U.S. Environmental Protection Agency implemented a regulation requiring all underground storage tanks (USTs) in the U.S. to meet new specifications by December 1998.

By the time the rule took effect, gas station owners had come a long way toward compliance. According to EPA`s Sept. 30, 1998, tally, 1,236,007 underground storage tanks had been closed by the time the rule took effect-a larger number than the 891,686 still active tanks that had been equipped to comply with EPA`s new requirements.

Many tanks were found to have been leaking (leaking underground storage tanks are called LUSTs). EPA reports 371,387 confirmed releases from LUSTs. As of early this year, a total of 314,965 cleanups had been initiated, and 203,247 of those had been completed.

These compliance efforts have been costly. The average tank upgrade has cost about $100,000, and EPA estimates that the average cleanup has cost $125,000 recently. Indeed, the cleanup cost seems conceivably equal to the life savings of a gas station owner if one visualizes a sole proprietorship with an owner-operator.

The idea was to make such a person responsible for damage to the groundwater on the rationale that the groundwater is public drinking water. If an underground fuel tank leaks, lawmakers thought, the groundwater might be permanently contaminated and forever unfit for drinking. A thorough cleanup seemed a worthy use for a gas station owner`s retirement nest egg.

While public sympathy took the form of taxpayer dollars contributed to cleanup programs, nearly all corrective actions were undertaken by LUST owners and operators.

EPA tried to leave state governments some latitude in enforcing UST standards. The agency broadly required that USTs must have, among other things, overflow prevention, leak detection, and corrosion protection systems of various kinds.

Where leaks had occurred, EPA mandated "free product removal." This meant that dirt was excavated and, if affected, groundwater was pumped from specially drilled cleanup wells in order to remove free product "to the maximum extent practicable."

If only a small amount of dirt was contaminated, the cost was as low as $10,000. More extensive soil contamination cost up to $125,000. If groundwater was involved, costs ranged from $100,000 to over $1 million for drilling wells, pumping and treating water, monitoring, and so forth.

It was especially hard to eliminate spilled petroleum products from substrata and groundwater by pump-and-treat methods. It was like trying to get gasoline or oil out of a rag by gently rinsing the rag with tap water.

Leak studies

It wasn`t until November 1992 that EPA began a policy of condoning taking risk into account when implementing corrective action under UST corrective-action requirements.

EPA regulations have generally given state governments latitude in regulating LUST cleanups. The EPA required state or local authorities to protect human health and the environment, leaving state governments to mandate the exact particulars of cleanup programs.

Subsequently, more facts specifically relating to LUSTs and groundwater have come to light. In 1995, the California State Water Resources Control Board received a stunning conclusion from a study conducted by Lawrence Livermore National Laboratory in conjunction with the University of California (UC) at Los Angeles, UC Santa Barbara, UC Berkeley, and UC Davis: Microbes eat spilled petroleum products underground, and pump-and-treat remediation is unnecessary. Likewise, excavation of contaminated dirt proves only marginally helpful, since nature readily eliminates free product in a reasonable length of time. Leaving free product buried where it spills is the best method of disposal in most cases, the report concludes.

The Lawrence Livermore team reviewed California`s database of 28,051 fuel tank LUST cases extending over 10 years. It found that only 136 of the leaks had reportedly affected drinking-water wells.

The team incorporated a recent review of 36 LUST case files involving 55 reportedly contaminated water supply wells. Only 25 of the wells had contamination that could be attributed to the LUST releases. Most of the wells were shallow, private, domestic wells near the LUST sites; 11 were on-site wells.

In another recent California review-a review of Napa County`s 57 cases of groundwater pollution-51 cases were examined. In 90% of these, plumes did not extend beyond 200 ft from the leaking tank.

Likewise, the California State Water Resources Control Board examined "perhaps the largest (data set) ever compiled that deals with the impact of fuel hydrocarbon releases over an extended geographic area," according to Rice, Grose, et al. Lawrence Livermore reports that this study found that plumes extended no more than about 250 ft in 90% of these cases. Bacteria multiply along a plume`s boundary and drive it backward like a huge army driving a battle front.

The Lawrence Livermore study found pump-and-treat remediation ineffective. Hundreds of volumes of water may be required to flush spilled fuel off of soil particles. The success of pump and treat is largely due to the coincidental action of bacteria.

Bacteria even eat benzene. Excavation combined with pump and treat doesn`t increase the probability of reducing plume average benzene concentration by more than 30% over a no-action alternative. Where no action is taken, beyond stopping the leak, bioremediation (petroleum product consumption by bacteria already native to the soil) will generally reduce plume mass by a factor of 10 in 1-3 years time.

The Lawrence Livermore report finds that, to recover a perceived property-value loss of a few tens of thousands of dollars, cleanup efforts can cost millions of dollars at a site with groundwater that poses a minimal risk or has limited beneficial use.

The average cost of pump-and-treat groundwater cleanups has been $637,000/acre-ft of California water. New water supply sources can normally be developed at a cost of $700-900/acre-ft in California. The water that is affected by leaking underground fuel tanks is almost always shallow groundwater that was originally not recommended for use due to susceptibility to contamination from sewers, septic fields, etc. The total volume of California groundwater affected by leaking underground fuel tanks is less than 0.0005% of California`s groundwater resources.

In response to the findings presented in the Lawrence Livermore report, Walt Pettit, the executive director of California`s State Water Resources Control Board, instructed his subordinates to hasten closure of LUST sites where only soil was affected. He also ordered them to cease active remediation of most groundwater involving LUST sites.

Efforts disproportionate

Bioremediation makes its alternatives look truly ridiculous. Microbial processes can be easily enhanced, moreover.

Ann Hasbach reported in 1998 strikingly successful bioremediation results at a gas station in southern New Jersey, where the installation of new underground storage tanks proved a barrier to treatment methods involving excavation.

Significant soil and water contamination were found to have been left from the previous tanks when the new ones were installed. Microorganisms were injected into bore holes. Samples taken 60 days later showed contaminant concentrations to have decreased by more than 99%! Rapid improvement of the groundwater was also demonstrated. The remediation was completed in just 90 days.

There have been hundreds of thousands of very costly excavation and pump-and-treat cleanups. Over a million underground storage tank closures and hundreds of thousands of costly upgrades have now been completed. Ironically, as more information became available, most of this exorbitant effort appears to have been unnecessary and unjustifiable based on the actual benefits obtained.

Bibliography

• Emond, Mark, "With the Clock Ticking, Marketers Push Harder for UST Compliance," National Petroleum News, Vol. 89, No. 6, June 1997, p. S3-S11.
• Hasbach, Ann, "In Situ Bioremediation Selected for Brownfield Site," Pollution Engineering, Vol. 30, No. 9, September 1998, p. 66.
• Marxsen, Craig S., "Why Stagnation?" B>Quest (www.westga.edu/~bquest/1999/stagabs.html), Feb. 8, 1999.
• Pettit, Walt, "Letter to All Officers of the California State Water Resources Board," Dec. 8, 1995.
• Rice, David W., Dooher, Brendan P., Cullen, Stephen J., Everett, Lorne G., Kastenberg, William E., Grose, Randolph D., and Marino, Miguel A., "Recommendations To Improve the Cleanup Process for California`s Leaking Underground Fuel Tanks," Lawrence Livermore National Laboratory Report, UCRL-AR-121762 (www.llnl.gov/environment/ erd/rice/), Oct. 16, 1995.
• Rice, David W., Grose, Randolph D., Michaelsen, Joel C., Dooher, Brendan P., MacQueen, Donald H., Cullen, Stephen J., Kastenberg, William E., Everett, Lorne G., and Marino, Miguel A., "California Leaking Underground Fuel Tank (LUFT) Historical Case Analyses," UCRL-AR-122207, Nov. 16, 1995.
• U.S. Environmental Protection Agency, "Corrective Action Measures for First Half of Fiscal Year 1998 (www.epa.gov/OUST/cat/camnow.htm), June 2, 1998.
• U.S. Environmental Protection Agency, "Underground Storage Tanks; Technical Requirements and State Program Approval; Final Rules, Part 280, Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks," Agency 53 FR 37082-37247, FR Doc. 88-21153 (www.epa.gov/OUST/fedlaws/techrule.htm), Sept. 23, 1988.
• U.S. Environmental Protection Agency, "Use of Risk-Based Decision-Making in UST Corrective Action Programs," Oswer Directive 9610.17 (www.epa.gov/OUST/directiv/ od961017.htm), Mar. 1, 1996.