Micropiles below Groundwater at the South Auditorium Block Site, Buffalo, NY-Paper

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The former Buffalo Memorial Auditorium site in Buffalo, New York, was redeveloped as Canalside, including a four-story children’s museum built above the auditorium’s surviving subbasement. The subbasement floor lies about 10 feet below groundwater and Lake Erie’s water level. Its approximately 4-foot-thick waffle slab and original piles could not support the new building, so micropiles were installed through the floor into bedrock.<br /><br />Because drilling through the slab’s waterproofing system risked uncontrolled water infiltration and damage to the permanent seal, the team used standpipes bolted to the floor with neoprene gaskets. The water inside each standpipe balanced groundwater pressure during drilling. After installation, the micropile casing and surrounding annulus were tremie-grouted to displace water and seal the system.<br /><br />A mock-up installation revealed leakage before grouting, prompting revisions to the procedures. Production work presented further challenges: the 75-year-old slab varied in condition, and renovation features—including utility trenches, soil-filled areas, and water infiltration—sometimes made the specified standpipe connection impractical. The team adapted the installation details to suit local conditions.<br /><br />Leakage also occurred when grout was lost from the annulus and failed to hold after standpipes were cut off. The team found that cement-bentonite grout performed better than cement grout alone; fast-setting polyurethane pressure grout was used where rapid leak control was needed. With these changes, the remaining micropiles were installed successfully.<br /><br />The 9⅝-inch-diameter micropiles had steel casing seated in bedrock, 3- to 10-foot rock sockets, and full-length center bars. They were designed for compression loads up to 334 kips and tension loads up to 261 kips. Tight constraints around existing structures and slab grade beams required unusual pile layouts, large pile caps, and accommodation of eccentric loading.

Keywords

Buffalo Memorial Auditorium

Canalside

children’s museum

micropiles

bedrock

subbasement

waterproofing

tremie grouting

groundwater infiltration

steel casing