Cost overruns on several multimillion-dollar building projects may have been caused by management and oversight problems at the state Department of Public Works, according to a state auditor’s report. Increased costs on 10 building projects could have been a result of inadequate monitoring of construction change orders. Auditors also found that the agency neglected reviews of subcontractors and failed to send $140 million in contracts to the state attorney general’s office for review, bypassing state regulations.