The Loudoun County Board of Supervisors has voted down a proposed amendment to the vicious dog ordinance that would have allowed dogs "one free bite."

An amendment proposed by Broad Run Supervisor Steven Stockman would order the destruction of any dog not kept under restraint that bites a human without provocation for a second time.

Stockman's proposal had come before the board previously but had been referred to the supervisors' public services committee for study. In a meeting last week, the committee voted unanimously, with Guilford Supervisor Betty Tatum absent, to "pass by indefinitely" any action on the matter.

As it stands, the county ordinance specifies that dogs confirmed as livestock killers can be ordered destroyed, but the code does not address dog attacks on people.

The board also voted last week to readopt 60-day emergency legislation regulating the application of Class A sludge on farmland. In August, the supervisors adopted the emergency legislation because at least one county farmer had an application pending with the state to have sludge applied to his land. That ordinance required only that sludge haulers obtain a permit from the county before transporting sludge from the Blue Plains Wastewater Treatment Plant and applying it to Loudoun farmland.

With their action last week, the supervisors added two new requirements. The first is that any company in the business of hauling sludge for application in Loudoun County must furnish to the county a performance bond of $100,000 to be used in case of spillage or other damage that the county determines has occurred and has not been corrected within 24 hours.

According to the second amendment, a sludge hauler must, each time he seeks a permit to apply the material, show the county proof that he has liability insurance amounting to $1 million, and must maintain that insurance throughout the time covered by the permit.

In other action, the board voted 5 to 3 against a plan to pro-rate personal property taxes beginning in 1987. County staff members had said that the program, through which residents and former residents would be taxed for the period of time they owned personal property, such as a car, rather than for the entire year, would bring in approximately $200,000 in additional revenue. However, the staff also said the program would require additional office space, equipment, and up to nine new employes, all of which could cost about $150,000.

In another matter, the board decided to have the county health department conduct a survey of the sewage systems in Aldie, to check for possible drainage problems and offer solutions.