While the property was on the New York State Department of Environmental Conservation (NYSDEC) priority list for several years, and preliminary site testing and assessment had been performed previously, the full extent of the contamination was unknown.
Aztech started the project by removing the entire petroleum infrastructure; which included nine large tanks, four sets of piping runs, eight pumps and a canopy. When the equipment was removed, it became obvious that there was a large scale petroleum release at the site. (Field screening observed odors and staining erased any doubt as to the severity of the spill.)
The project included removing the most obvious material and disposing of it at an approved municipal landfill. The team discovered that the contamination had spread under the building. It was determined that this structure would need to be razed to access the soil below.
Aztech removed most of the soil from the spill core, a total of approximately 2,000 cubic yards of gasoline-impacted soil was removed and transported to municipal landfills.
With the spill assessed at 17,000 cubic yards of impacted soil, total offsite removal of all soil was rejected due to the prohibitive cost. After a sustainability study, it was determined that soil farming was the most economical choice.
An on-site treatment strategy that included a bio-remedial approach similar to the approaches presented in NYSDEC’s STARS Memo #2 was selected to address the remaining impacted soil. Soil farming allows the volatile organic compounds (VOCs) found in petroleum spills to disperse through evaporation. The affected soil is dug out and aerated, screened, and spread out in thin layers, or lifts, allowing the VOCs to vent openly. Fertilizer is then added to encourage biological growth, and then it is seeded with grass and hay for erosion control.
Post excavation analytical data indicated that the remedial excavation was successful in completely removing the soil impacted by petroleum above regulatory standards. In fact, in most cases, the soil exhibited non-detectable (ND) concentrations.
The site was situated in a low-lying, swampy area. As such Aztech engineers had reasonable expectation of groundwater infiltration. As the digging commenced, groundwater began to seep into the excavation as expected. Infiltrated groundwater was intercepted and transferred to holding tanks. After the solids settled out of the captured water, the water was treated via Aztech’s portable 4,000 pound activated charcoal filtration system, which was 100 percent efficient for removing dissolved contaminants from the water. The treated water was later discharged into a drainage feature located on the site.
Currently the site is remediated; field screening of the soil treated indicated ND to minor PID readings. As such, the spill file for the site has been closed.