Now that the $5.2 billion merger of Westlake Village home builder Ryland Group Inc. with Irvine’s home builder Standard Pacific Corp. has been completed, the combined company plans to lay off about 10 percent of its total workforce, the Los Angeles Times reports. It could result in about 280 employees losing their jobs. The combined company, CalAtlantic Group Inc., is now the fourth-largest residential home developer in the nation.