Project Details

Client: Weis Builders Inc
Location: Rochester, MN
Services: Earthwork, Utilities


The Berkman Apartments, located directly across from Mayo Clinic’s Saint Mary’s Hospital, is constructed over one of the most geotechnically challenging sites in Minnesota. Bolander worked hand-in-hand with Alatus, Weis Builders and Braun Intertec to develop and implement adaptable deep foundation methods to support the 14-story concrete structure.

Braun, relying on their extensive experience in this region, recommended alternating between cased micropiles and drilled piers.  Micropiles were used in areas of weak soils and/or voids and drilled piers could be utilized on competent bedrock. To bring order to highly unpredictable karst subsurface conditions, Bolander developed a flow chart that accelerated the team decision making process when soft soils or voids were encountered.  Further, Bolander provided schedule and cost saving solutions by fabricating a custom drill rig to quickly discover and evaluate voids before foundations were drilled.

Micropile drilling was challenging and unpredictable with depths as shallow as 50-ft and as deep as 120-ft.  Drill pier foundations were drilled through 35-ft of competent bedrock.

Foundations By the Numbers:

  • DTH Micropile: 256-Each (13,879-LF)
  • Drilled Piers: 130-Each (3-ft to 8-ft Diameter)