Subject to subsection (b) of this section and §§ 21–205 and 21–206(a) of this subtitle, the Commission may enter on and take possession of remaining land or interest in land described in item (2) of this subsection and proceed with the extension or construction of a water supply, sanitary sewer, or stormwater management project if the Commission: has acquired or is acquiring by purchase or other procedure, including the condemnation procedures provided for in the Real Property Article and Subtitle 1 of this title, at least one–half of the takings of land or interest in land required for the extension or construction of the project; and determines that the remaining takings of land or interest in land are needed for the extension or construction of the project. A building may not be taken under this subtitle.