Officials with the Department of Ecology are continuing to investigate the extent of contamination from Thursday's diesel spill when two semi-trucks collided near Wallula Junction.
About 200 gallons of diesel spilled onto Highway 730 and into a ditch, but it did not reach any surface water, said Jani Gilbert, an Ecology spokeswoman.
Burns Oil of Oregon has been hired as the cleanup contractor and workers were back at the spill site Friday to see where the diesel ended up, she said.
"After the weekend, they will likely be digging to find the extent of the contamination," Gilbert said.
There still is no concern that any diesel made it into the waterways, she said, noting that it would have had to tra-vel about 75 feet horizontally to get to the Columbia River.
"We're not worried about that, but we want to make sure we get all the diesel out of the soil," she said.
Officials with the state Department of Transportation and Union Pacific Railroad also were investigating. The ditch runs along the railroad tracks, so the agencies will work together to develop a cleanup plan, Gilbert said.
Thursday's crash occurred when the driver of an unloaded semi-truck tried to make a U-turn on the two-lane highway about five miles west of Wallula Junction and struck a semi carrying potatoes, causing it to spill its load.