Designer Bugs Eat Contamination.

Bioremediation--a clean up method in which tailor-made bacteria are injected into a contaminated site to ingest a pollutant--is growing in popularity.

For years, a Florida hospital's underground piping associated with its petroleum storage tanks leaked in a tightly contained area of the facility's courtyard. When free product--the petroleum that contaminated the site-- was discovered years later during closure of the tank, the situation seemed to call for a traditional remediation solution: dig up the contaminated soil, haul the affected soil off-site, and eliminate the potential for the contamination to spread within the site. Introduce a maze of sewers, utility lines and a walkway above the contaminated area, however, and such a remediation scenario becomes infinitely more difficult and dramatically more costly.

Choosing a remediation method that can provide both a safe and cost-effective cleanup where excavation is not feasible may be a thorny process. The good news, however, is that advances in remediation methods are providing more options, especially in the case of bioremediation.

In the above-mentioned case, the hospital administration, its insurance company's claims department, and a highly qualified environmental services firm weighed a variety of remediation options to determine the safest, most cost-effective cleanup option. Soil analytical results associated with the tank closure procedures at the hospital area indicated petroleum constituents that exceeded state soil cleanup target levels.

Similarly, groundwater analytical results indicated petroleum constituents exceeded groundwater cleanup target levels and natural attenuation default source concentrations. Standard remediation methods--simply digging out the contaminated soil, hauling it off for treatment, and replacing with clean fill--were simply not possible. Because the affected area was covered by a walkway, intertwined with sewer and utility lines, and tightly confined among hospital buildings (which include the ICU), the only method available to remove impacted soil from the site would be with a hand shovel. Such a painstaking procedure would take years of manual labor and cost millions of dollars in response costs and costs associated with the disruption of critical hospital activities.

The other available option was a technique that is growing in popularity, known as bioremediation. Bioremediation is a cleanup method by which tailor-made bacteria are injected into the contaminated site literally to eat away the contamination. The bacteria are cultured to break down specific families of petroleum products as they consume the carbon component of the hydrocarbon molecules. Specifically, the best available and practical technology is enhanced bioremediation, using inert nutrients, and American Type Culture Collection Class 1 (ATCC C1) bacteria.

In the hospital situation, the bioremediation option would cost tens of thousands of dollars, as opposed to a multimillion dollar cleanup bill. Bioremediation, however, required additional special approval from the environmental officials in the county where the hospital was located and as in any cleanup, environmental service contractors with the appropriate expertise.

In various studies, aerobic bacteria have been shown to break down hydrocarbons more rapidly than anaerobic bacteria. Therefore, ample oxygen was also a requirement for successful aerobic enhanced bioremediation of this particular site. Several bioremediation vendors offer formulations that include a proprietary inert chemical, known as COGEN V, that help aerobic bacteria scavenge oxygen from surrounding water molecules for metabolic needs, instead of relying solely on dissolved oxygen. Until they are ready to be used on site, the bacteria are stored in spore form within suspension matrices, the two most common of which are bentonite clay and corn starch. A bentonite clay suspension may be used during an initial injection in anticipation of a minimal number of required treatment events. But the suspension may be supplemented with corn starch in the anticipated need for multiple applications.

The bioremediation process begins by mixing microorganisms with a liquid formula of nutrients and proprietary oxygen-scavenging chemicals to create a slurry. The slurry is then pressure-injected into subsurface soils through a steel injection tube that is advanced into the shallow soils in areas identified for treatment remediation. Petroleum-impacted groundwater is treated by injecting the slurry into injection points installed specifically for the bioremediation effort.

The hospital remediation work plan included installation of several groundwater injection points to deliver the nutrient, microbe and COGEN slurry into two areas of the contaminated site. Following initial treatment, up to two inches of free product was observed in a monitoring well in each affected area. The appearance of elevated levels of free product on the water table at first seemed to indicate a worsening of the problem, but in fact was attributed to the successful liberation of stratified petroleum impacts from the overlying soils. Monthly injection retreatments were performed to maintain the introduced nutrients, bacteria and especially the COGEN concentrations in the impact areas. Following initial treatment, the free product thickness decreased appreciably.

Monthly groundwater sampling monitored progress of the bioremediation, as did monthly organic vapor field screenings of the area's soils. During the first six months of enhanced bioremedial treatment, the stratified soil impacts were reduced and free product was reduced to less than a measurable thickness. A total of seven to eight treatments are anticipated necessary to finish the remediation at the health care facilities, followed by one year of post-treatment monitoring. The end result though is a two-year cleanup acceptable to the state regulatory authority that will be accomplished at a reasonable cost with minimal disturbance to the hospital and its critical care unit.

Great Potential

At first, bioremediation posed an option whose results were uncertain at best, which was not easily tailored to individual sites, and which posed significant regulatory hurdles. Great strides have been made in biosciences and the end result for this remediation method has been the creation of tailored organisms designed to ingest a particular kind of pollutant.

The U.S. Geological Survey (USGS) conducted studies on microorganisms naturally found in soil and found that some were actively consuming fuel-derived toxic compounds and transforming them into harmless carbon dioxide. The studies showed that the rate at which these microorganisms can consume the toxic compounds is increased if the microorganisms are given certain nutrients. By providing nutrients, the natural microbes increase their rate of biodegradation of the pollutants. By 1992, USGS scientists were testing this natural method of remediation by introducing nutrients to contaminated soils, which resulted in a 75 percent overall contaminant reduction within one year. Along with technical advances has come greater acceptance and approval of bioremediation technology from the regulatory community.

In controlling costs of remediation, bioremediation has proven effective in certain circumstances. First, bioremediation treats contamination in-place. Most of the costs associated with traditional remediation methods involve the physical removal and disposal of contaminated soils. Clearly, the elimination of removal and disposal costs can result in substantial savings. Additionally, bioremediation uses natural processes that do not rely upon invasive or intensive manual labor. The processes involved in bioremediation reduce labor costs, although they do require that qualified professionals oversee and monitor the process. Another significant benefit of this process, particularly in the above case, is that it reduces environmental stress to the surrounding areas, especially in and around areas of limited access.

Risks Nonetheless

Bioremediation offers promising remediation opportunities. The process appears especially conducive to areas sensitive to excavation, such as wetlands, and tightly confined properties, such as in urban settings, where access to impacted soils is restricted, and where such attempts can be disruptive to adjacent operations, tenants or businesses.

With the success of bioremediation comes the need for a precautionary note, however. The growing acceptance of the process has spurred a new growth area of "fly-by-night" bio-contractors. As a result, companies contemplating the retention of such remediation specialists need to be especially aware of their qualifications, reputation, and employee credentials. For example, having a licensed geologist on staff may be advisable to ensure proper oversight of this complex procedure. In addition, it may also be advisable to work with professionals, such as insurance claims experts, legal counsel, and remediation contractors that have the regulatory knowledge in this growing area.

Finally, when employing an emerging cleanup method such as bioremediation, the importance of a thorough and appropriate work order contract cannot be stressed enough. To control costs and future liability, a contract for a bioremediation project should determine a guaranteed closure for the site. In other words, the contract should require the remediation contractor to provide a provision limiting payments for additional treatments or bacteria injects should the process take longer than the contractor determined at the onset.

To control costs, minimize a company's liabilities, and maximize the use of the best available technologies, it is important to know what remediation options are available and what will work best in the situation at hand. While bioremediation is not the answer for every environmental cleanup, it is proving to be a very viable, cost-effective alternative for some.

Matthew Ford is an environmental claims counsel for ECS Claims in the Atlanta regional office. Headquartered in Exton, Pa., ECS, an XL Capital Co., is an underwriting manager providing integrated environmental risk management solutions worldwide.