Case Study 98-49: A Case of Night Dumping?

A client conducting a cleanup of fuel oil in soil noted that the fuel content of the soils increased dramatically one summer. They contacted Investigative Science to conduct a forensic investigation to determine the source of the fuel. The client believed that someone was dumping fuel on their site.

We conducted our investigation by interviewing the staff working at the site (other consultants) and collecting our own samples for analysis at our own lab. Our analysis showed that the levels of fuel in the soil were in line with those collected in previous years and did not show the huge increases detected by the client.

We next reviewed the procedure used by the other consultants to take samples and perform the analysis. We found some interesting anomalies. First the consultants who were used to pulling fuel tanks, were deliberately selecting the dark bits of soil rather than attempting to collect representative samples. Second, the samples were analyzed by a local lab by flame ionization GC without any cleanup of the sample to remove interferences. 

We found that the dark chunks of soil selected by the consultants were enriched in peat moss. This material gave a positive interference in the GC assay of about 10,000 parts per million in the diesel fuel organics range. This material was duly reported by the lab as diesel range organics. These two confounding factors accounted for all of the increase in the "fuel" levels.