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MADISON – Agriculture officials are reminding farmers to routinely inspect polyethylene tanks used to store fertilizer and pesticides. There have been several recent failures leading to chemical spills.

“Last year four out of 39 reported agri-chemical spills were caused by poly-tank failures, and so far this year that number is four out of 35 spills,” said Rick Graham, spills-response coordinator for the Wisconsin Department of Agriculture, Trade and Consumer Protection. “These tanks do have a ‘shelf life.’ You need to inspect them at the beginning and end of the season.”

Cleanup is costly, requiring removal of the contaminated soil and either land-spreading or land-filling it. The farmer is responsible for cleaning any contaminated soil, although some cleanup costs may be reimbursed through the Agricultural Chemical Cleanup Program.

Polyethylene tanks may be placed in fields for the growing season or they may be mobile -- pulled on carts or placed in truck beds. They are common because they are readily available, relatively inexpensive and resistant to corrosion. But they are susceptible to weathering, especially if they are always outdoors in sunlight. Ultraviolet radiation from the sun affects the material. The tanks become brittle and may split open, spilling the contents.

Estimates for shelf life vary from 12 to 18 years, depending on where the tank is kept and how it was designed. But tanks may start showing signs of ultraviolet-ray damage after five to eight years.

Graham said farmers should check the tanks for any obvious signs of weakness -- such as cracks or straps cutting deeply when used to hold mobile tanks in place. A less-obvious sign of a problem is “crazing” – a network of fine cracks that may not be visible to the eye or noticeable to the touch. Producers can test for crazing by rubbing a water-soluble marker over small sections of the tank and then wiping it off with a dry cloth. If crazing has occurred, ink will have soaked in and made the crazing visible.

Another test is to simply hit the empty tank with a baseball bat, he said. It sounds extreme but a tank that is sound will not be harmed. One that cracks was already unsafe.

Any agri-chemical spill must be reported as soon as it's discovered by calling 800-943-0003. The number is answered 24 hours per day. Visit datcp.wi.gov and search for “spills” for more information.