HERMISTON -- Both a brush fire and an unrelated leak of mustard chemical agent vapor inside a storage igloo were reported at the Umatilla Chemical Depot Monday.
At no time did the public appear to be in danger.
The fire burned along the south end of the depot near Interstate 84 Monday afternoon, which is not close to the area where chemical weapons are stored.
It was reported about 1 p.m. and firefighters were mopping up hot spots Monday evening. Firefighters from the Boardman and Hermiston fire departments helped the depot fire department.
Earlier in the day trace amounts of mustard chemical agent vapor were detected for the sixth time this year inside an igloo.
"These aging relics of the Cold War tend to leak in the hotter months," said Bruce Henrickson, depot spokesman.
But the Umatilla Chemical Agent Disposal Facility is making progress in incinerating the mustard, a blister agent developed as a weapon, and its containers.
It has incinerated 37 of the ton-containers that hold the mustard agent and has about 2,600 left. Each container holds about 1,400 to 1,800 pounds of mustard agent and 45,415 pounds of it have been destroyed so far.
Processing has begun slowly as planned since the first containers were moved June 4 from depot storage to the disposal plant. The plant should be operating at full speed about November.
That will put the plant on schedule to complete incineration of the last mustard agent from summer 2010 to mid-2011, Henrickson said. Then about two years will be required to disassemble the incineration plant.
Incineration of the containers was halted for a little over a week after mercury readings were detected June 30 in the Metal Parts Furnace Pollution Abatement System. A container expected to include mercury was being processed.
An Environmental Protection Agency lab confirmed low levels of mercury. However, the release was within emission limits, Henrickson said.
An investigation concluded that a valve had not closed in the Pollution Abatement System and processing resumed after the valve and carbon filters were replaced.
The leak detected Monday was within a storage igloo and posed no danger to the public or environment, said depot officials. It was the third leak of a mustard container within a storage igloo this month, following two leaks in May and one in June.
The mustard freezes below 59 degrees and as the weather warms, the mustard containers thaw and are more likely to leak.
The igloos have a passive filtration system that prevents chemical agent vapor from escaping the structures. When a leak is discovered, a powered filtration system also is installed.
w Annette Cary: 582-1533; email@example.com.