Sasol has raised by nearly $1 billion the estimated cost of its chemical project under construction near Lake Charles to a range of between $12.6 billion and $12.9 billion.

The estimate includes a $300 million contingency. In February, the South Africa-based company estimated the cost at $11.6 billion to $11.8 billion, up from $10.9 billion estimated at the end of December and an original estimated in 2014 of $8.9 billion.

The company also had reported that the first of seven production facilities at the Lake Charles project had achieved beneficial operations, meaning the linear low-density polyethylene unit sustained production at set specifications for at least 72 hours. The remaining Lake Charles manufacturing units are expected to reach beneficial operations throughout 2019 and early 2020 as projected, the company said Wednesday, though one unit was pushed back by one month to February 2020.

Sasol said a review of cost estimates followed a number of changes to the management of the Lake Charles project. The review confirmed the $10.9 billion estimate made on Dec. 31 was accurate and complete, but resulted in concerns related to the forecasting process and the increase in the projected total cost. Weaknesses in the project's controls were identified and are being remedied to strengthen the oversight, leadership for the project and frequency of reporting, the company said.

Sasol's stock dropped nearly 15 percent in trading Wednesday.

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