Underpinning of the adjacent chapel and hospital was accomplished using auger installed bracket piles and a tangent pile grout wall.  Tangent piles were installed in a sequence of altering soldier piles (primary piles) and grout piles (secondary piles) ultimately forming a continuous grout pile wall eliminating the need for lagging as the excavation progresses.

    Soldier piles were installed by first augering a hole and pumping a slurry to hold the hole open.   A soldier pile was lowered into the slurried hole.  A high-strength cement grout was tremie pumped to displace the slurry and encase the soldier pile.  Secondary grout piles having minimal reinforcing were installed tangentially to the previously installed soldier piles.  Earth tie-backs were installed to support the lateral loads as the excavation progressed.​

Drilling second level of tiebacks:

Completed Excavation:

Slurry Mixing:​


St. Francis Hospital, Roslyn N.Y.

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Macro Enterprises completed the design and installation of a sheeting and underpinning system for a 50 foot deep excavation for a new parking garage. 

 The Sheeting system consisted of steel soldier piles, timber lagging and earth tiebacks.  Soldier piles were installed without impact noise or vibrations by advancing a continuous flight hollow shaft auger into the ground for the full length of the soldier pile.  A self-hardening slurry was pumped through the hollow shaft to hold the hole open while the auger was being withdrawn.  The soldier pile was lowered into the slurried hole.  After the slurry hardened, timber lagging and grouted earth tie-backs were installed to resist the lateral earth pressures as the excavation proceeded. 

Installing Tangent Grout piles at Casey Pavilion:

Chapel, first row of tie-backs

Conventional concrete underpinning with steel wedges and drypack were used to support building loads were the excavation depths were not as great.​

Pile Foundations - Shoring Engineers | Established 1977