Several factors to consider before deciding to remove an underground storage tank

As part of a buyer's due diligence, a phase one environmental site assessment (ESA) was commissioned on an office building. The results indicate an old heating oil tank is buried under the rear parking lot. The building converted to natural gas many years ago and the building has been sold several times since the conversion. There is no documentation on the tank and although the phase one ESA recommended further evaluation, the deal had to close quickly. The seller would not make any representation of the tank including the size of the vessel (if they purchased the building without a phase one or the report missed the tank they may not know it even exists). Nor would they allow the ability to conduct further investigation prior to closing. Other business factors require you to close on the transaction and take possession of the building as is. Obtaining financing is something you are interested in, but understand the bank will want this buried tank situation brought to a conclusion. The decision now is whether to remove the UST or abandoned in place. In order to make the best decision, there are several factors to consider. The first question is the size of the tank vessel? If the tank is greater then 1,100 gallons, any work will need to follow the New York State Department of Environmental Conservation (NYSDEC) protocols. If below 1,100 gallons, the tank is considered a non-regulated tank, and therefore the process will not require their approval. However, many local environmental agencies may have a set of protocols to adhere to that may impact the final decision as well. Typically regulatory bodies prefer a buried tank that is not in use be removed and properly disposed of. There are some advantages to this strategy. For instance, if the tank is going to be removed, soil borings are not typically required in advance. Upon excavating the old vessel, soil samples can be obtained at the bottom of the excavation by placing the soil into mason jars that are sealed and delivered to a laboratory for analysis. This process eliminates the cost of hiring a firm to advance soil boring prior to the removal process. A good remediation firm can get a feel for the quality of the soil before sending them to a laboratory. Discolored soil with petroleum odors usually can be considered "hot or impacted." The excavator will stockpile this soil on-site for proper disposal at a later date. Since the pit is open, it will be easier to see the impacted soil and remove it immediately. When the remediation firm or consultant hired by the client determines that the impacted soil has all been removed, the endpoint sampling can be conducted. Upon receipt of acceptable soil quality, clean fill can be placed back in the excavation and a final sign off from the regulatory body supervising the work can be achieved. Should the owner decide to conduct sampling prior to the tank removal, the results may recommend additional sampling in order to determine how much soil is impacted which will add to the cost of the project. Abandoning a tank in place is also acceptable but there may be a few more hurdles to clear. The main issue will be convincing the regulatory body that there is a structural integrity issue to the building adjacent to the location of the tank. In addition, there may be access issues that prevent the appropriate equipment from getting to the location of the tank. If a new building at the adjacent property was constructed after the buried oil tank was installed at the subject site, this can impact the ability to remove the old buried tank vessel. In a tank abandonment, soil borings will need to be advanced as outlined above including at the bottom of the tank. In order to achieve this goal, the tank will need to be cut open; all products (oil, sludge, etc.) will need to be removed and properly disposed of. The tank will then need to be de-vaporized for explosive gases and then a soil sample can be obtained by drilling through the bottom of the tank to obtain the last sample required. Upon receipt of the acceptable laboratory results, the tank will be filled with an inert material typically an approved foam, sand or concrete slurry. Once again final sign off from the supervising agency is important to demonstrate to the lender as well as a future purchaser that the tank issue was properly addressed. Chuck Merritt is the president of Merritt Environmental Consulting Corp., Hauppauge, N.Y.