Fairfax County has sold $311 million in bonds that will pay for improvements at schools, parks and recreational facilities, public safety buildings and commercial and redevelopment areas, officials said. The proceeds will also be used to refinance previously issued bonds.

The bonds, rated Aaa/AAA/AAA, were tax-free general obligation bonds for public improvements and "refunding" bonds used for the refinancing. They were sold last Thursday at the second-lowest interest rate achieved by the county since the AAA rating was first awarded by Moody's Investor Services in 1975.

The bonds were sold to Lehman Brothers at an interest rate of 3.56 percent. The previous lowest rate the county received for 20-year bonds was 3.54 percent in March. The total net interest cost on the new public improvement bonds will be approximately $139.7 million.

Officials said the county received six bids for the bonds with a high bid of 3.589 percent. The closeness of the bids indicates the highly competitive nature of the sale, county officials said in a news release.

Voters approved the bond sales in referendums held from 1988 to 2002. The proceeds from the most recent sale will provide about $200 million, to be split among schools ($125.59 million); parks and park facilities ($13.92 million); public safety facilities ($54.75); and commercial and redevelopment area improvements ($4.5 million).

The balance of the proceeds will be used to refinance previously issued bonds, officials said. The refunding will result in savings of approximately $8.18 million of the bonds refunded. The refunding bonds were sold to take advantage of current market conditions and low interest rates, officials said.