A mobile detector system designed to warn soldiers if they are under invisible chemical, biological or radiological arms attack is about to face some tough tests.

That includes measuring how well it can respond to such attacks if delivered by Scud missiles, artillery barrages or now-infamous "improvised explosive devices" hidden along roadways. Up to 30,000 pounds of explosives will be used, along with tens of thousands of liters of chemicals and biological agents.

The tests won't come in Iraq with real weapons. They will come in the Utah desert, with what the Army says are relatively safe materials designed to simulate characteristics of real, deadly chemical and germ weapons.

Dugway Proving Ground this week published a legal notice in Utah newspapers saying it performed a required environmental assessment of the planned tests, and found they will have "no significant impact" on people or the environment.

It will accept public comments on that report and its findings until March 20 — and then tests are scheduled for April on the detector system with a long name: the Joint Services Lightweight Nuclear Biological Chemical Reconnaissance System.

Documents say the tests — which worry at least one local watchdog group — are designed to challenge the detector "with real-world threat scenarios using realistically delivered chemical warfare agent simulants and agent of biological origin simulants."

Last July, the Deseret Morning News reported that Pentagon inspectors were complaining that several similar detection systems now in use might not actually work or survive in contaminated areas that they are designed to detect.

The Morning News obtained reports by the U.S. Army Audit Agency complaining that several such detection systems either had not been rigorously tested in tough battlefield conditions, or had failed such tests earlier conducted at Dugway.

In this new round of tests, Dugway documents say the exercises will be "under intense, realistic threat conditions."

Three-man crews riding either in specially equipped Air Force Humvees or eight-wheel Marines Light Armored Vehicles are scheduled to traverse 14,000 acres of test areas within the Rhode Island-sized base to determine how well the system can detect and handle simulated chemical and germ attacks — and map boundaries of their contamination.

Some attacks are designed to be smaller, as if detonated and spread by an improvised explosive device along a road.

Some larger attacks are planned, as if they were delivered by an artillery barrage. (Some preset explosive detonations will simulate that).