MACHINERYPADSTABILIZATION

Addressing Problem #1: Structural Support With Push Piers

 

Foundation Tech determined that ECP PPB-400 push piers with PPB-350-IP inertia sleeves would be the most economical way to lift and permanently support the machine pedestal — without disassembling the shear as the 2004 repair had required.

But sizing the pier system required more than just calculating the static weight of the pedestal. A typical foundation repair uses a safety load factor of 2 to 2.5 times the static weight. That standard is adequate for buildings, where loads are relatively constant. It is not adequate for a 70-ton rebar shear.

Consider what this machine actually does in a single day of operation:

• 500 cycles per day, on average
• 100 pieces of rebar cut per cycle — meaning 50,000 individual cuts daily
• Every cut delivers a downward shock that momentarily multiplies the effective load far beyond the pedestal’s 140,000 lb static weight

 

Over thousands of cycles per week, hundreds of thousands per year, that dynamic loading is what caused the 2004 repair to fail. The reinforcements were engineered for the weight of the machine, not the impact of the machine working.

Foundation Tech engineered the pier system to two levels of assurance: an 8× ultimate safety factor based on the PPB-400’s rated ultimate capacity, and a working-load safety factor greater than 4× based on the pier system’s continuous operating capacity — both well above industry standards for foundation repair.

The Engineering Behind the Pier Specification:

• Total pedestal weight (static load): 140,000 lbs
• Piers installed: 12 total
• Ultimate capacity per pier: 99,000 lbs (ECP PPB-400 rated)
• Total ultimate capacity: 1,188,000 lbs (~8.5× static load)
• Working load per pier: 49,500 lbs
• Total working load capacity: 594,000 lbs (~4.2× static load)
• Inertia sleeves (PPB-350-IP) installed in every pier section
• 14,000 psi high-strength grout filling every pier, top to bottom
• Hydraulic installation pressure: 8,600 psi per pier
• Average installation depth: 65 feet

 

Each pier was driven to an average depth of 65 feet at an installation pressure of 8,600 psi — independent, site-specific confirmation that every pier had reached competent load-bearing strata before the machine was set back down.

Triple-Reinforced for Dynamic Shock: Pipe, Sleeve, and Grout

A standard push pier is an unfilled steel pipe. It carries load vertically extremely well, but under severe dynamic shock and lateral forces — exactly the conditions at Gerdau — a hollow pipe can flex, buckle, or fatigue over time, especially at the depths involved here. And in loose sandy soils like those at the Fontana site, a standard pier can actually lose working capacity because the surrounding soil doesn’t provide enough lateral support to keep the pipe from deflecting under load.

For an application this demanding, Foundation Tech engineered each pier with three layers of structural reinforcement, working together as one composite column:

Layer 1: The ECP PPB-400 steel pier pipe itself — a 4-inch outer-diameter pipe driven to 65 feet at 8,600 psi hydraulic pressure, with an ultimate mechanical capacity of 99,000 lbs.

Layer 2: ECP PPB-350-IP inertia sleeves installed inside every pier section — 3-1/8-inch diameter reinforcing tubes with a 0.180-inch wall thickness, nested inside the main pier pipe. The sleeves do two critical things that matter enormously in Fontana’s alluvial soil:

• They reinforce the couplings between pier sections, which are the most common failure points under lateral or eccentric loads
• They prevent the pier from “snaking” or buckling through weak, loose, or water-saturated soil strata — restoring the pier’s ability to actually deliver its full 49,500 lb working capacity in soil conditions that would otherwise force a significant capacity down-rating

 

Without the inertia sleeves, a standard PPB-400 installed in Fontana’s sandy loam would have to be de-rated for insufficient lateral confinement. With the sleeves, each pier can reach and hold its full rated working load — even in the low-blow-count zones where water migration had previously washed the fine particles away.

Layer 3: 14,000 psi high-strength grout, filling every pier top to bottom — transforming the steel-and-sleeve assembly into a fully composite structural column. The grout fills every internal void, locks the sleeve and pipe together as a unified structure, and delivers the final layer of rigidity and long-term durability.

The result is a pier system that is categorically different from a standard installation. A hollow-tube pier with no sleeve and no grout is what you might see under a typical residential foundation. A sleeved, grout-filled PPB-400 pier, installed 12 times at 65-foot depth with 8× ultimate capacity and matched to the specific soil mechanics of the Fontana alluvial fan, is an industrial-grade support system engineered specifically for machinery that never stops hitting the ground.

Proof-Tested In Place, Built to Last

The significance of every one of these numbers is this: push piers are proof-tested as they’re installed. It is not a hope. It is a measurement.

• Twelve piers, driven to 65 feet, each confirmed at 8,600 psi installation pressure
• Every pier reinforced with an ECP PPB-350-IP inertia sleeve to guarantee full rated capacity in weak soil
• Every pier filled with 14,000 psi grout for composite-column rigidity
• Combined system capacity exceeding 8× the static pedestal load at ultimate rating, and over 4× at continuous working load

 

Unlike the 2004 approach — which added weight and reinforcement to the machine while leaving the failing soil untouched — the push piers transfer the load of the pedestal past the unstable soil entirely, bearing the weight of the machine on competent strata far below. And because the system was engineered with inertia-sleeved, grout-filled composite construction and verified at installation, it doesn’t just support the pedestal at rest — it supports it through every one of the 500 daily shear cycles, every hour of every production shift, for decades to come.

Addressing Problem #2: Soil Stabilization Against Liquefaction

 

During excavation for the pier installation, Foundation Tech confirmed exactly what the geology had predicted: the soil directly beneath the pedestal was a high-sand mixture with significant liquefaction potential.

But understanding why that liquefaction risk was so pronounced at this specific site requires zooming out beyond the property line.

The Water Story Starts a Mile Away

The Gerdau foundry sits less than a mile from the base of the San Gabriel Mountains — and roughly five miles uphill from the river valley below. That elevation differential is significant, and it drives a hydro-geological reality most surface-level soil reports never capture.

During rain events, water doesn’t just fall on the foundry site and drain away. It moves through the foundry site — traveling underground from the mountain range toward the river valley, following the natural gradient through the porous alluvial soil. Every major storm pushes substantial volumes of water through the subsurface beneath Gerdau’s operations.

Each pass of that underground flow does two things:

• It carries fine soil particles away, creating voids and undermining what was previously dense ground
• It temporarily saturates the sandy loam, bringing it to the edge of liquefaction right at the moment the 70-ton shear is still delivering 500 daily shock cycles above

 

The combination is what makes this site genuinely dangerous from a soil mechanics standpoint. Vibration alone will slowly settle loose sandy soil. Saturation alone will slowly erode it. But saturated sandy soil under constant vibration is the textbook definition of a liquefaction scenario — where soil briefly loses its ability to support load entirely.

Why Excavation and Replacement Wasn’t an Option

A complete removal and replacement of the soil bedding would have required shutting the machine down, excavating underneath it, hauling material offsite, and recompacting engineered fill over the course of weeks. That was precisely the kind of extended downtime Gerdau could not afford — and it would have left the underlying hydro-geology unchanged anyway. New compacted fill, placed back into the same water-migration pathway, would have eventually faced the same problems.

The Solution: Gradient-Depth Polyurethane Injection

Foundation Tech engineered a solution designed specifically to address both the loose soil structure and the water migration threat: HMI 401 polyurethane deep injection, installed in a gradient pattern at six separate depths around the pedestal.

Injection depths: 3 ft, 5 ft, 7 ft, 9 ft, 12 ft, and 15 ft.

This staggered-depth pattern is a deliberate engineering choice, not a blanket application. Each layer of injection has a specific job:

• Shallow injections (3–5 ft) fill the voids created by years of water migration and settle-induced compaction directly beneath and around the pedestal footings.
• Mid-depth injections (7–9 ft) stabilize the zone where the loamy sand transitions into the underlying alluvial matrix — the layer most vulnerable to cyclic disturbance from the shear’s vibration.
• Deep injections (12–15 ft) create a stabilized zone well below the active vibration envelope of the machine, locking up the soil structure at depths where water migration can no longer reach the pedestal from below.

 

The Root System That Locks the Soil Together

Here is what makes gradient-depth HMI 401 injection uniquely suited to this kind of subsurface damage: the polyurethane doesn’t just fill a single void and stop. It follows the soil’s existing weaknesses.

As the polyurethane expands outward from each injection point, it seeks out every void, crevice, and seepage channel left behind by decades of water migrating downhill through the soil profile. The expanding foam follows those natural pathways, branching into them, filling them, and binding them together — ultimately creating a continuous, interconnected root-like structure throughout the treated zone.

That root system does two things at once:

• It stabilizes every void simultaneously. Each branch of the foam network locks up a pathway that was previously open to water flow or soil movement. Where the soil was once riddled with scattered weaknesses, it becomes a single integrated mass.
• It pressurizes and compacts the surrounding soil. As the foam expands, it doesn’t just fill empty space — it actively pushes outward against the soil around it, compressing loose sand and gravel into a denser, stronger matrix. The result is a treated zone that is stronger than the original engineered soil would have been, let alone the degraded version the machine was sitting on.

 

This is the critical advantage of injection-based stabilization over traditional methods. Excavation and replacement can only give you as much density as the fill material arrives with. Polyurethane injection creates density in place, by force, throughout every layer of the soil profile — including the layers that are physically impossible to reach from above without demolishing the structure first.

What the Polyurethane Accomplishes

Across all six depths, as the root system develops, the HMI 401 polyurethane:

• Fills voids left behind by decades of water migration and fine particle loss
• Compresses and densifies the surrounding sandy soil, dramatically increasing its bearing capacity
• Locks soil particles in place so they can no longer be reorganized by vibration
• Creates a hydrophobic barrier that redirects subsurface water flow around the treated zone rather than through it — protecting against future erosion from the San Gabriel runoff
• Cures within minutes, allowing installation to proceed without the days-long wait required by traditional grouts

 

The gradient depth pattern is what makes the repair comprehensive rather than superficial. A single-depth injection would have stabilized one layer of soil and left the others vulnerable. By injecting at six progressive depths — and letting the polyurethane network together across every depth — Foundation Tech built a treated soil zone that functions as an integrated, multi-layer support system. From just below the pedestal all the way down to a depth where underground water flow is no longer a factor, the soil is no longer a collection of loose particles waiting to be moved. It’s a single, stabilized, load-bearing matrix.

The complete project we complete in ten days, and there hasn’t been a shutdown due to misalignment of the shear in eight years.