Complex sentence: It was then sold to Valeroin 2004, and it was open for a number of years, and closed in 2009; in December 2010, Valero announced plans to reopen the refinery.
Split into simpler sentences: It was then sold to Valeroin 2004, and it was open for a number of years, and closed in 2009. In December 2010, Valero announced plans to reopen the refinery.