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PierTech Systems Engineer Value Engineers a Matt Slab Project in Tennessee Specifying (16) 3.50” to 8.625” Transitional Helical Piles

by Rachel Everett

February, 2024

PierTech Systems, with headquarters in Chesterfield, MO (,was recently approached by a customer in Tennessee seeking help from PierTech Engineer, Bret Anderson, for an opportunity to value engineer and convert a micro pile matt slab foundation design to a helical pile alternative design. The initial design included (16) - 5” cased micropile to 50 ft. An alternative was explored due to the relatively costly and labor-intensive process of installing the (16) cased micropiles.

The soils encountered within the upper 38 ft. were considered low to medium strength. Beyond this layer the bearing strata was a very dense Clayey Sand (SC) with Gravel. Maximum loads at the head of the pile were 45 kips compression, 11 kips tension, and 4 kips lateral.  The lower axial load, and higher lateral load allowed for a transition pile design from a slender shaft section (3.5” OD) from 0 to 30 ft. and a large diameter shaft section (8-5/8” OD) from 30 to 40 ft.

The design was accepted by the customer as an approved alternative. All piles were successfully installed over a couple days using a PierTech SD95 drive head outfitted with a digital torque monitor.

Pier Tech Systems Pier Tech Systems

For more information:

PierTech Systems

17813 Edison Ave.

Suite 100

Chesterfield, MO 63005


Number of Piles : 16

Pile Size: 3-1/2” first 30 ft, Transition to 8-5/8” for 10ft

Average Installation Depth: 439ft

Average Final Installation Torque: 20,000 ft-lbs.

Lead Project Engineer: Bret Anderson, P.E.

Loads: 45 kips compression, 11 kips tension, and 4 kips lateral