Freedom Industries, the West Virginia company whose chemical spill last week tainted the drinking water of more than 300,000 residents in and around Charleston, filed for Chapter 11 bankruptcy on Friday.

In documents filed in federal bankruptcy court in Charleston, a lawyer for the company stated that the spill apparently occurred after a broken water line caused the ground to freeze beneath an aging chemical storage tank, pushing an unidentified object into the bottom of the tank.

The resulting puncture allowed 7,500 gallons of 4-methylcyclohexane methanol, a chemical that washes impurities from coal, to escape the tank on Jan. 9 and leach into the Elk River, the source of drinking water for Charleston and surrounding communities.

The area’s main water intake is about one and a half miles downstream from the cluster of 13 tanks where the leak occurred. Residents were warned not to use the water for the next five days, and 14 were hospitalized for exposure to the chemical.