The board may adopt an ordinance which establishes a civil penalty for the wrongful demolition, razing or moving of part or all of a building or structure when such building or structure has been designated as an historic structure or landmark or is part of an historic district. The civil penalty shall be imposed on the party deemed by the court to be responsible for the violation and shall not exceed twice the fair market value of the property, as determined by the county real estate tax assessment at the time of the demolition, razing or moving. An action seeking the imposition of such a penalty shall be instituted by petition filed by the county in circuit court, which shall be tried in the same manner as any action at law. It shall be the burden of the county to show the liability of the violator by a preponderance of the evidence. An admission of liability or finding of liability shall not be a criminal conviction for any purpose. The filing of any action pursuant to this section shall preclude a criminal prosecution for the same offense. The defendant, within twenty-one days after the filing of the petition, shall file an answer and may, without admitting liability, agree to restore the building or structure as it existed prior to demolition, razing or moving. If the restoration is completed within the time agreed upon by the parties, or as established by the court, the petition may be dismissed from the court’s docket upon a finding by the court that the building or structure has been restored as it existed prior to demolition, razing or moving. Nothing in this section shall preclude action by the zoning administrator under subdivision A 4 of § 15.2-2286 or by the county under § 15.2-2208, either by separate action or as a part of the petition seeking a civil penalty.