U.S. Army Corps of Engineers is testing equipment at Salt Plains National Wildlife Refuge near Jet in Alfalfa County to determine what will be most effective in its on-going safety assessment and evaluation of the salt crystal beds.

The salt crystal digging area, which was closed in April after chemicals found in World War II training kits were unearthed, likely will remain closed through the summer, said refuge manager Jon Brock.

“Last week, the Corps of Engineers tested some equipment to see what would work in locating any more potential unexploded chemicals stored in glass vials,” Brock said.

The equipment utilizes ground penetrating radar and metal detectors, he said.

Approximately 134 vials of blistering solutions used in World War II chemical warfare training kits have been unearthed about a mile from the public entrance to the crystal digging site since a Bartlesville Boy Scout accidentally unearthed a single vial on April 21.

The vial broke, exposing the boy to a yellowish liquid inside. He started coughing, and the material made his eyes burn and his nose run. He has suffered no lingering ill effects, federal officials said.

An Army chemical unit from Aberdeen, Md., was ordered to the site and found more vials nearby and incendiary devices apparently used in an attempt to destroy them.

U.S. Department of Fish and Wildlife officials ordered the 300-acre digging area closed until the Army Corps of Engineers completes a thorough assessment of the area.

In addition to testing equipment for detection purposes, Corps of Engineers has hired a contractor to re-evaluate the area where the vials were found. That work is expected to begin in July, Brock said.

Engineers also have checked records and aerial photographs to determine what may have been recorded when the military used part of the Salt Plains area as a bombing range between 1942 and 1946. What has baffled officials is records show while much of the northern half of the salt flat was used as a bombing range, the area where the vials and incendiary devices were found was not.

Salt Plains National Wildlife Refuge had approximately 150,000 visitors in 2006, with a fifth — or 30,000 — digging for crystals.

Brock said in a conversation he had with Great Salt Plains State Park Manager Russell Nickel that camping visitation at Salt Plains is down 20 percent so far this season and likely is attributable to the closing of the crystal digging area.

Crystal digging is allowed April 1 through mid-October each year.

“As soon as we reopen, we’ll put the word out to everyone,” Brock said.