SCOTTSBLUFF, Neb. -- Work is continuing near the Burlington Northern Santa Fe railroad tracks along Avenue I in Scottsbluff because of indications of dissolved benzene, reports the Scottsbluff Star-Herald.

The chemical was spilled during a train derailment Nov. 4.

Employees of Retec, a company based in Concord, Mass., are doing the work.

First, a well is drilled. Then, the hole is filled with a special compound that allows oxygen to be absorbed into the soil, said Retec Site Manager Dieter Geithner.

Scottsbluff Mayor Dave Boeckner said he was aware of the drilling.

"I know (the railroad) has gone to do some more test wells that are a little further out than what they have been doing. It's part of their process to continue to monitor any flow of the benzene through the groundwater system in that area," Boeckner said.

He added that the groundwater in the area may be spreading the contamination "somewhat" but that the railroad is continuing to monitor the situation to see how much movement has occurred.

Boeckner said he doesn't feel the public should be alarmed with the procedure.

"They're doing their job. I think this is exactly what we want them to do by being aware of what's going on with the groundwater system and with the potential here for the contamination and to keep track of it and keep removing it," he said.

Concentrations of benzene in the affected area are below drinking water standards, indicating that it can be cleaned up in a relatively short period of time, said Steve Forsberg, the railroad's general director of public affairs and corporate relations.