The San Francisco Airport Commission refunds $110 million in fixed-rate revenue bonds with new variable-rate bonds to lower its overall interest cost.  •  The San Dieguito Union High School District responds to the turbulent auction-rate market by converting $90 million in ARS bonds to fixed-rate securities.  •  De La Rosa & Co. generates $41 million of retail orders to reduce yields and save the L.A. County Metropolitan Transportation Authority significant interest costs on a $25-million Sales Tax Revenue Bond issue.  •  The L.A. Community Redevelopment Agency obtains a strong investment-grade rating on a $12.5-million Taxable Tax-Allocation Bond issue for the Westlake Recovery Project.  •  Despite a tough market, Beverly Hills successfully refunds $31 million in water revenue bonds and $17 million in wastewater revenue bonds for economic savings.  •  The Gridley Redevelopment Agency clears various hurdles caused by tightening credit in the municipal market to successfully execute its first tax-allocation bond financing.  •  Riverside issues unenhanced Bond Anticipation Notes to mute the effects of the collapse of auction-rate securities and prudently control interest costs.  •  The Sacramento Regional County Sanitation District restructures $50 million in auction rate securities with better performing, direct pay variable-rate bonds backed by letters of credit.  •