(425) 391-8585

"Cornerstone is the best underground utilities contractor in town. I use them on all of my projects because I work on a lot of environmentally critical areas. I trust Cornerstone to deliver on my toughest jobs."

– Jon Riser

Underground Utilities

Cornerstone Construction is a Registered Side Sewer Contractor. We routinely install a wide variety of underground structures and pipes.
  • New Sewer and Storm Mains.
  • New Water Mains.
  • New Manholes and underground Vaults for all utilities.
  • Detention Tanks and Detention Ponds.
  • Sewer, Storm, and Water service lines to buildings.
  • Conduit for T.V., Phone, Power and Gas
  • Fire Sprinkler Service.
  • Storm Drain Catch Basins in the street and Curb Inlets.
  • Downspout and Footing Drain pipes around new foundations.
  • Footing Drains and Under Slab Capillary Break Drainage.
Seattle Underground Utilities Contractor