508-347-9101 info@sterling-eng.com

Design – Case Study 4


Client Need


This institutional client located in downtown Boston, MA required a new campus wide, phased design to update existing underground steam piping infrastructure including redesign of underground structures, rerouting of steam and condensate (gravity and pumped) piping through existing buildings and underground throughout campus. Design included expansion compensation for all piping to prevent damage to insulation and carrier pipe. New piping interfaced with existing steam and condensate piping systems within buildings across campus.

Design Features

  • Provided three methods of non-invasive underground survey of existing utilities in the proposed path of piping which included ground penetrating radar (GPR), electromagnetic induction (EMI), and precision utility location (PUL).
  • A fourth method of invasive exploratory excavation was used to accurately survey critical points where necessary. This invasive approach was limited to discreet areas to minimize impact to the campus environment.
  • Field survey information was converted to a 3D Revit model which was utilized to minimize impact of existing underground systems outside the scope of the project.
  • New design was integrated into 3D Revit model to better understand overall geometry and limitations underground.
  • Every section of pipe was analyzed for expansion including resolution of forces and allowance for expansion and contraction within reasonable limits to prevent damage to insulation and carrier pipe.
  • Mechanical expansion joints were utilized within underground structures and expansion loops were utilized whenever it was advantageous to do so.
  • Details included bedding, backfill, anchoring, supports, saddles, guides, field joints, penetrations, gland seals, manholes, installation of isolation valves, and connections to existing services.
  • Field inspection of every critical component including every welded field joint and every jacket penetration prior to backfilling.
  • Minimized or eliminated shut down of services to individual buildings through coordination of work with owner and contractors.

Design Benefits

  • Provided client with a new, reliable underground steam and condensate system with minimal or no impact or interruption of services to campus wide buildings, many of which support ongoing experimental laboratories that require tight temperature and humidification tolerances.
  • Reduction in energy loss due to old and damaged underground steam and condensate piping insulation and overall increase in central steam plant efficiency.
  • Upfront underground survey minimized impact to outdoor campus environment and landscaping areas during construction. Also minimized unforeseen underground conditions.