Va. Code § 21-381
No bid at any sale shall be received unless sufficient in amount to discharge all the drainage assessments and other charges due by the delinquent lands or owner thereof, together with all costs and expenses of sale. If no sufficient bid be received, the board of viewers shall be deemed the purchaser at a sum sufficient to pay all assessments which are due, and costs, as above stated, and shall be entitled to receive a certificate of purchase and deed in the manner provided by law for purchases at tax sales. The board of viewers shall only be required to pay the costs and expenses of sale before receiving a certificate of purchase, and no lands shall be subsequently sold for drainage assessments while the board of viewers holds a certificate of purchase or deed therefor.
Va. Code § 21-381