Carlos Bustamante is charged with assaulting the women while on the job with Orange County's Public Works Department, between 2003 and last year.
Bustamante's attorneys argued prosecutors violated state rules of professional conduct by making "scurrilous comments" about him.
The judge rejected that and also denied a motion to have the Orange County District Attorney's Office taken off the case.
Bustamante is charged with six counts of false imprisonment, three counts of assault with the intent to commit a sexual offense and one count each of stalking, attempted sexual battery by restraint and grand theft by false pretense. The grand theft charge stems from expense reports he submitted after attending a 2 1/2-week program in Boston, prosecutors said.
Bustamante also faces one misdemeanor count each of battery, assault, sexual battery and attempted sexual battery. He could face up to about 28 years in prison if convicted.
City News Service contributed to this report.