Harry J. Phillips Jr., a Houston investor...

Harry J. Phillips Jr., a Houston investor who effectively owns control of American Ecology Corp., was elected chief executive of the Agoura Hills-based operator of hazardous-waste sites, the company said Monday.

Phillips succeeds William E. Prachar, who remains chairman. However, Prachar also has agreed to relinquish that post to Phillips early next year after Phillips obtains actual majority control of American Ecology’s stock.

The executive changes were expected after Phillips’ investor group, Ecol Partners Ltd., bought preferred stock and other securities from Browning-Ferris Industries Inc. for $16.6 million last July. The securities, upon full conversion into American Ecology’s common stock, will give Phillips a 52% stake in the company.

Prachar also has agreed to remain a director of American Ecology through next year.