Va. Code § 21-305
Whenever a supplementary petition signed by the owner or owners of any tract of land in the proposed district, be subsequently filed with the clerk of the court, requesting that tile be used to drain the tract, the clerk shall immediately notify the engineer of the district of such petition. The engineer shall thereupon design and lay out a system of tile drainage upon the tract, and the board of viewers appointed to classify the lands in the district, as hereinafter provided for, shall, in the schedule of classification, place a special assessment upon the tract and also classify the tract in a class which will result in the total assessment being equal to the cost of the tile drainage of the tract, in addition to the proportional part of the liability for other benefits derived from the drainage canals of the district.
The tile drainage system shall become part of the proposed drainage district, and shall be governed by all the provisions of this chapter, insofar as the same may be applicable.
Va. Code § 21-305