Diesel spill’s threat to aquifer is unclear

The good news is that a northeast Spokane diesel spill will probably not contaminate drinking water wells.

The bad news is that the fuel at an Avista-owned facility at Market Street and Magnesium Road leaked through its containment area and into the ground over the Spokane-Rathdrum Aquifer.

Officials estimate 28,000-31,000 gallons leaked into the ground – enough to fill the Silverwood water park’s dumping bucket 50 times.

“We don’t know yet what the impact to groundwater is,” said Department of Ecology spokeswoman Jani Gilbert.

The aquifer is located about 100 to 125 feet below the site, but the closest wells are either upstream from the spill site or miles downstream, said Reanette Boese, Spokane County’s groundwater coordinator.

The water in the aquifer travels 50 feet a day on average, Boese said.

North Spokane Irrigation District Manager Gary Lowe said that the large leak occurred in his district, but is not endangering its wells.

“I think if they were going to have a spill, they found a pretty good place to have it,” Lowe said.

The problem started Sunday night when a tanker driver delivering fuel for Cenex, which leases the facility, pumped diesel into a tank already partially full.

“There was some sort of mix-up over whether they were delivering or taking fuel. They delivered, and we thought they were taking fuel,” said Avista spokesman Hugh Imhof.

Imhof said that Avista switches valves to send or take fuel to and from the tanks inside a closed building. The person delivering the fuel would have been outside the structure and unable to see the fuel spilling out of the tank.

Avista discovered the spill Monday morning and reported it to the Washington Department of Ecology that afternoon, said Gilbert. Initial estimates were that just 1,000 gallons spilled, but they were later revised upwards.

The tanks are located within a containment area, but that didn’t prevent the leak.

“For some reason, some of the fuel found a crack and seeped down under it,” Imhof said.

Although Ecology, county and local water district officials agreed the leak happened over the aquifer, Imhof said it was just outside the aquifer zone.

“We’re pretty confident it hasn’t reached any groundwater yet, and it hasn’t reached the aquifer,” he said.

Avista has already taken some test samples and is in the process of cleaning up the site.