Mark D. Thayer, CPD, is an associate and senior plumbing systems designer with HSMM AECOM in Roanoke, VA. Thayer has 23 years experience in plumbing systems design and presently serves as president of the ASPE Virginia Blue Ridge Chapter. Thayer serves as Work Group Chairman for the development of a Design Standard on Vacuum Plumbing Systems under the ASPE Design Standards Committee. Thayer can be reached at (540) 857 3299 or mthayer@hsmm.com.