Va. Code § 15.2-3531
The voters of any locality whose governing body has not taken the initiative under § 15.2-3529, may require it to do so by filing a petition with the governing body. The petition shall be signed by not less than fifteen percent of the voters of the locality registered to vote as of January 1 of the year in which the petition is filed, which number in no case shall be less than 100, and shall ask the governing body in accordance with § 15.2-3529 to effect a consolidation agreement with the localities named in the petition and to petition the judge for a referendum on the question. All of the signatures on the petition must have been made within twelve months. A copy of the petition of the voters shall also be filed with the judge of each circuit court having jurisdiction in the county or town or the judge of the circuit court in the city. If the governing body within one year is unable, or for any reason fails, to perfect such consolidation agreement, then the judge of the circuit court having jurisdiction in the county or town or the judge of the circuit court of the city shall appoint a committee of five representative citizens of the locality to act for and in lieu of the governing body in perfecting the consolidation agreement and in petitioning for a referendum.
When a consolidation agreement adopted under the provisions of this section proposes the creation of a consolidated city which will include at least one existing county, the petition shall ask for proceedings pursuant to §§ 15.2-3521 through 15.2-3528 prior to such referendum.
Va. Code § 15.2-3531