When workers dug up two rusting steel storage tanks from beneath the parking lot of 111 Santa Rosa Ave. in 2006, Joan Fleck noticed something curious.
The experienced regulator for the North Coast Water Quality Control Board observed that the tanks appeared to have been "tucked in" with a bed of gravel and covered by a layer of sand.
It was as if someone had uncovered the tanks and piping while grading the site, covered them back up and built a parking lot on top of them.
"They were exposed at one point," Fleck said. "Someone had to have seen them to drape this gravel blanket over the top of them."
Whether anyone knew about those two tanks at the time of the development of the office building in 1989 may never be known.
Hal Musco, the managing partner of the group that developed the property, died in 1993. Richard Colombini, a partner in the group and local commercial builder who built the four-story office building, said he never knew about the tanks back then.
"Had we known they were there, we would have dealt with it," Colombini said this week. "We had no idea in hell that all these tanks were in the ground."
But he and others did know about a third tank, one that regulators believe wasn't dealt with properly and continues to contribute to the contamination on the property.
Colombini recalls that during the excavation work for the parking lot, workers reported running into a long steel tank on the southern portion of the site, very close to a high-pressure gas line.
Records show that in February 1989, David Lampi, a son-in-law of Musco, requested a hazardous-waste permit from the Santa Rosa Fire Department to allow the tank to be abandoned in place.