The William S. Hart Union High School District is asking Los Angeles County officials to consent to a second series of school construction bonds authorized by Santa Clarita Valley voters under Measure SA.

Approved at the ballot box in November 2008, Measure SA authorized the school district to issue up to $300 million in bonds to pay for a future high school in Castaic and other school construction projects. Bonds are repayed by property owners through the property tax – but property owners aren’t assessed until the district incurs the debt.

The Hart District issued a first series of Measure SA bonds for $75.2 million in June 2009 – its first debt under the measure – leaving $224.8 million available. Now it’s asking the Board of Supervisors to consent to the issuance of a new series of Measure SA bonds for $70 million, leaving about $154.8 million available for future draws.

Supervisors are scheduled to consider the request Tuesday. At that time they would also levy sufficient taxes to repay the principal and interest, and instruct the county auditor-controller to add the taxes to the property tax rolls.

The Hart District school board authorized the issuance of the bonds Sept. 7.