Timelapse of large ammonium nitrate storage inflated in Elkhart, Texas

Timelapse of the Airform membrane inflation for a 20,000 ton ammonium nitrate storage in Elkhart, Texas.

Mike South

Wayne Norsworthy

Wayne Norsworthy with El Dorado Agricultural Products turning on the inflator fans.

Mike South

It’s Monday morning, January 6, and Wayne Norsworthy with El Dorado Agricultural Products flipped the switch to the inflator fans. A 115-foot diameter by 92.5-foot tall Airform began to inflate. Soon the tallest building in Elkhart, Texas is a Monolithic Dome Airform.

Work began in late 2019 to replace an older, wood structure with a Monolithic Dome to store 20,000 tons of granular ammonium nitrate fertilizer. The dome increased storage capacity at the retail fertilizer facility, but — more importantly — it increased safety.

In 2013, an ammonium nitrate storage exploded in West, Texas, killing 15 people, injuring 200 more, and damaging — or destroying — nearby homes and businesses. In 2015, Texas passed increased regulations for storing ammonium nitrate. Since then, municipalities are working with fertilizer companies — who employee people from these communities — to better store this vital fertilizer.

In Elkhart, the silo shaped Monolithic Dome enabled the fertilizer company to store more ammonium nitrate while meeting and exceeding the safety requirements by Texas and the City of Elkhart.

Inflated membrane

The newly inflated Airform membrane towers over the neighboring buildings at the retail fertilizer plant in Elkhart. A wood structure was razed to make room for the dome.

Mike South

“Scheduled to be completed in March, the giant igloo looks a bit out of place among the ‘old-timey’ aesthetic for which Elkhart is known,” reported William Patrick for the Palestine Herald-Press. “Elkhart Mayor Jennifer McCoy told the Herald-Press the location of the dome keeps it from breaking with the look of the town — and regardless, safety trumps all else.”

“I applaud El Dorado’s commitment to public safety,” McCoy said. “That is so much more important than if it looks modern.”

Conveyor augment and 3D x-ray illustration

The foam and concrete construction of the dome will extend into the small, protruding augment. When complete, the inflated end is cut off and the finished, reinforced opening will be used for the loading conveyor. This x-ray illustration of the finished structure shows how the product nearly fills the entire structure. AC equipment on the tunnel actively maintains a cool, dry climate inside the dome, reducing caking and corrosion.

Javier Figueroa photo and Mike South illustration.

The completed facility will load ammonium nitrate from railcars through an elevator and conveyor system into the dome. The product will pour — inside at the top — into a pile that is easily contained by the steel-reinforced concrete structure. The storage volume of the domed silo is significantly larger than the wood building it replaced without using any additional land.

A strong, steel door at the dome opening will allow nitrate to flow out into the tunnel where front-end loaders can retrieve material to be mixed with other fertilizer components and sold to area farms.

The finished structure will open in the Spring.

Aerial view of fully inflated membrane

Aerial view of the fully inflated membrane near the railcar siding in Elkhart, Texas.

Mike South