What are they blowing up at the Crane base in southern Indiana?

In early November, a dozen people called 911 to report explosions that rattled their dishes and shook the earth beneath their feet. The source of the disturbance: explosions from the Naval Support Activity Crane that were heard and felt miles away.

The noises arose from regular activities that take place on the base most weekdays during the summer and fall. Military munitions, in one form or another, have been part of the base’s mission since its founding.

In 1941, 64,000 acres in Martin, Greene and Lawrence counties intended for a park were diverted for the war effort. The federal Bureau of Ordnance dedicated the area as a Naval Ammunition Depot, where military equipment such as weapons, ammunition, combat vehicles and other equipment would be produced, tested and stored.

Since then, surplus military ammunition has been moved to what is now called Naval Support Activity Crane, the third largest naval base in the world.

How big is NSA Crane? How many people work there?

The 300-square-mile military installation, 30 miles southwest of Bloomington, employs about 6,000 people, most of whom are civilians.

The base also houses 700 Army personnel and the Crane Army Ammunition Activity (CAAA), which is responsible for removing surplus, outdated and unserviceable ammunition ranging from bullets to bombs.

The base does not handle non-conventional weapons such as chemical, biological or nuclear devices, said CAAA Public Affairs Officer Randy Tisor.

Why does Crane blow up ammo instead of another disposal method?

In December 2018, the National Academies of Sciences, Engineering, and Medicine published a comprehensive report commissioned by the Department of Defense. The goal was to summarize the current state of ordnance disposal and find alternative ways, other than burning and exploding, to better dispose of unused and obsolete items.

The 100-page study looked at the Defense Department’s demilitarization program for conventional munitions. It evaluated alternative technologies for destroying the items instead of open combustion (OB) and open detonation (OD), the current processes.

Although alternative and more modern technologies are available, one obstacle is blocking implementation: the high cost of changing the way war equipment is destroyed.

From the report: “The committee believes that there is only one barrier to the full deployment of alternative technologies in place of OB/OD – namely financing. Without a clear directive from Congress, accompanied by adequate funding, it will not be possible for the military to implement the full deployment of alternative technologies.”

How much does demilitarization cost?

Funding for the Army’s conventional munitions demilitarization program increased from $134 million in fiscal year 2008 to $251 million a decade later. The military expects that the nation’s demilitarization stockpile will continue to grow as additions exceed the amount that can be demilitarized with the funds provided.

During the five years leading up to the 2018 report, the average number of missiles added to the stockpile was about 86,600 per year. The average amount of conventional ammunition added was 53,700 tons per year.

Where does the Ministry of Defense store and destroy old ammunition?

There are seven military base depots spread across the country where the stock of conventional ammunition is stored. The Defense Department’s Joint Military Command oversees the demilitarization of “conventional” munitions such as bombs, mines and artillery projectiles, which account for 90% of the stockpile’s weight. The Army’s Aviation and Missile Command manages the remaining 10%, consisting of missiles and rockets. The agencies cooperate in determining which combination will be demilitarized in any given year.

How much no longer needed military ammunition is in the US arsenal waiting to be destroyed?

A lot of. In 2018, there were approximately 410,000 tons, or 820 million pounds, of military munitions waste waiting to be demilitarized. Some stocks are now much reduced due to ongoing removal efforts, while others may have grown in recent years.

Crane had the most in 2018: 132,800 tons of conventional munitions stored on the base, ready to be blown up or burned. The base has a capacity of 650,000 tons. According to the Crane Army spokesman, the base has reduced its stockpile in the six years since the report and now has 85,000 tons of conventional weapons material at its disposal.

There are six other military depots with supplies. The amounts stated are from the 2018 report.

• Hawthorne Army Depot, Hawthorne, Nevada: 94,900 tons

• McAlester Army Ammunition Plant, McAlester, Oklahoma: 82,800 tons

• Tooele Army Depot, Tooele, Utah: 48,640 tons

• Anniston Defense Munitions Center, Anniston, Alabama: 24,800 tons

• Blue Grass Army Depot, Richmond, Kentucky: 14,200

• Letterkenny Munitions Center, Chambersburg, Pennsylvania: 11,140 tons

What types of munitions are destroyed by open blast at Crane and other locations?

The government report lists examples of objects suitable for open detonation, including ammunition filled with explosives designed to detonate, such as projectiles, bombs, grenades and nuclear warheads, and motors of missiles and rockets. Other non-exploding objects are ignited and destroyed in giant above-ground fire pans.

Where does the open detonation take place at NSA Crane?

The 2018 report states that there are six primary demolition pits at Crane’s Army Ammunition Activity site. The weight limit for each well is 500 pounds per explosion, with a maximum of 70,000 pounds allowed on the range. Crane also has one scrap area for rocket engine disposal and a secondary range with a maximum weight limit of 1,000 pounds, the report said.

In an update this month, Tisor said Crane’s current open detonation range has 70 wells: 30 in the front and 40 in the rear. Each is capable of a net explosive weight of 500 pounds. “The front range and back range are fired on opposite days,” Tisor said.

What is the process for open blasting?

Ammunition is placed in a trench or pit with explosive charges, which is then covered with dirt. This process reduces the noise, shock and debris ejected during the explosion, which is initiated from a safe distance. The added explosives cause the ammunition to detonate underground.

The process leaves more solid residue, such as metal bomb and projectile casings, than open burning of non-explosive material. “The inert components are shattered into fragments of different sizes by the blast, and the fragmented metal components remain in the disposal trench and surrounding area,” the report said. “This makes cleaning up solid residues from open explosions more time-consuming and expensive than cleaning up residues from open combustion, which is usually limited to a combustion pan.”

How often does Crane detonate munitions on the base?

Tisor routinely confirmed. The underground explosions occur most weekdays during the summer and fall, he said, and then taper off as trees lose their leaves and winter atmospheric conditions occur, eliminating nature’s dampening of the loud booms. Local residents have probably noticed this delay.

The explosions, which often shake the earth and can be felt as far south as Monroe County, have been part of Crane’s mission for decades. Tisor said the Army has been clearing munitions there since 1977 and that the Navy was in charge of the work for 30 years before that.

Contact HT reporter Laura Lane at llane@heraldt.com or 812-318-5967.

This article originally appeared in The Herald-Times: What are they blowing up at Crane Military Base in Indiana?