Va. Code § 33.2-2604
A majority of the Commission, which majority shall include at least a majority of the total of chief elected officers and elected officials who represent the counties and cities embraced by the Commission, or their designees pursuant to § 33.2-2602, shall constitute a quorum. Decisions of the Commission shall require a quorum and shall be in accordance with voting procedures established by the Commission. In all cases, decisions of the Commission shall require the affirmative vote of two-thirds of the members of the Commission, or their designees, present and voting, and two-thirds of the total of chief elected officers and elected officials who represent the counties and cities embraced by Planning District 23, or their designees, who are present and voting and whose counties and cities include at least two-thirds of the population embraced by the Commission; however, no motion to fund a specific facility or service shall fail because of this population criterion if such facility or service is not located or to be located or provided or to be provided within the county or city whose chief elected officer's or elected official's, or its respective designee's, sole negative vote caused the facility or service to fail to meet the population criterion. The population of counties and cities embraced by the Commission shall be the population as determined by the most recently preceding decennial census, except that on July 1 of the fifth year following such census, the population of each county and city shall be adjusted, based on population estimates made by the Weldon Cooper Center for Public Service of the University of Virginia.
Va. Code § 33.2-2604