Anne Arundel County elections officials have certified a petition drive to try to halt a proposed slot machine site at a popular shopping mall in a referendum. The Anne Arundel County Board of Elections certified Thursday that 22,967 signatures gathered by foes of a casino at Arundel Mills mall are valid. Opponents of the site needed 18,790 signatures to put the proposal on the ballot in November. Baltimore-based Cordish Cos. has sued the board, contending that it overlooked fraud in the petition drive. Anne Arundel County Executive John Leopold said he has asked the county's Department of Planning and Zoning to halt consideration of plans filed to build a slots facility, pending a decision by the court or the voters.