In the middle of a severe winter with several feet of snow on the ground, a heating oil truck inadvertently pumped 2,000 gallons of oil into a sump that was part of a large buried septic leach field. The school was operating and now had no place for their septage.
HOW COULD THIS HAPPEN?
The fuel oil truck driver who had no experience delivering to the school’s Underground Storage Tanks (UST), was sent to make an emergency delivery due a low-level alarm on their electronic monitoring system. Because he was unfamiliar with their site, he connected the hoses to the school septic pump stations clean out pipe (which looked like a larger version of the fill/vent pipes on the side of your house) and delivered #2 fuel to the pump station which immediately discharged most of the fuel to the school’s two leach fields.
The spill was not discovered for a couple of days, until the school called to confirm the oil delivery, as the low-level alarm was still active, and the UST was manually measured confirming that no product was delivered to that tank.
St.Germain Collins (St.Germain) met with the Maine Department of Environmental Protection (DEP) and school officials to develop a game plan to quickly get the leach fields back online.
The team decide that the septage would be pumped temporarily from the sump on a daily basis and discharged at a nearby municipal wastewater treatment plan. St.Germain selected a contractor to excavate the two leach fields that were about 100 feet by 50 feet in size, and oversaw the excavation of 5,000 +/- cubic yards of contaminated soil. All contaminated soil was shipped offsite for later disposal.
Once the majority of soil was removed, St.Germain gridded the excavations and used oleophilic dye testing in the field to determine which portions of the excavation required additional soil removal. The oil penetrated the soil beneath the leach field in an irregular manner with some areas as deep as 9 feet while other areas were clean at a depth of 4 feet.
SUCCESSFUL REGULATORY CLOSURE
After replacement of the leach fields, the Maine DEP required the installation and sampling of monitoring wells around the new leach fields. St.Germain also sampled the school water supply. After several rounds of groundwater sampling with no contamination evident, the Maine DEP issued a regulatory closure letter.