WEST (CBS 11 NEWS) – State investigators visited the West Fertilizer plant twice in the weeks leading up to a deadly explosion. Records from the Texas State Chemist show the plant manager wanted them there on the most recent visit, to investigate a product that didn’t look right.

The recent visits were noted in nearly 200 pages of documents pertaining to West, at the state chemist office. Records show officials from the office were at the plant as many as 10 times a year over the past decade. There are several violations noted, usually for fertilizers that did not contain exactly the right chemical mixture.

State chemist Dr. Tim Hermann said West’s violations were about average for a company that size, and possibly a little bit better.

It was West general manager Ted Uptmore who reached out to investigators in the most recent contact, asking them to look at a shipment of diammonium phosphate that didn’t look right. In a letter, written the day before the explosion, the state said a sample showed the mixture was “off.”

Material safety data sheets show that combination however does not have the flammable properties of the ammonium nitrate that was stored on the site. Chemical inventory sheets filed with the state Department of Health Services show there was as much as 270 tons of the material on the property, 135-times more than was used in the Oklahoma City bombing.

The inventory sheet was filed as required this year with the state, and local emergency management and fire departments are also supposed to have it. The company would be required to report the information to federal authorities.

Despite the reporting requirements, and the large amount of ammonium nitrate on site, the plant was not the first thing that came to mind for some residents when the explosion happened.

“I knew the fertilizer plant was on fire, but then I knew we’ve got all this construction going on on the highway,” said West resident Krystal Vanek. “So then I wasn’t sure if something blew up at the construction, or if it was the fertilizer plant that actually blew up.”

Investigators said they were excavating a crate left at the site of the explosion. They are also doing 3-D imaging to obtain an accurate measurement of the crater. They described the work as similar to an archaeological dig, going layer by layer through the ground.

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