Alchatek Blog

A seawall rarely fails all at once. It starts small, a hairline crack near the waterline, a soft spot in the yard, a slight lean nobody notices until the pavers start pulling apart. The price of the fix grows every day you wait, because the damage behind the wall keeps progressing even when the surface looks stable. 

What a Failing Seawall Actually Costs

There's no single number that fits every seawall repair, but the relative cost structure is predictable, and it's worth understanding before you call anyone.

Targeted repair, filling the voids and stabilizing the soil behind the wall, is by far the least expensive path when caught early. Patch-and-repeat cosmetic fixes look cheap on any single invoice, but they don't stop the underlying erosion, so the cost adds up every time you have to call someone back. Full demolition and replacement sits well above both, often by a wide margin, because it involves permitting, heavy equipment, and rebuilding the structure from the ground up rather than restoring what's already there.

That gap between options is significant enough to change how a homeowner should think about a small crack today: fixing it now, while it's still a targeted repair, is not a close call against waiting until it becomes a replacement.

Exact costs vary by region, wall material, soil conditions, and severity. A trained contractor can give you an accurate number after a site evaluation.

The Root Cause: Why Seawalls Fail From the Inside Out

Most seawall problems don't start at the wall. They start behind it.

As water levels rise and fall against the wall, whether from tides, wave action, storm surge, or seasonal water table changes, water pushes through cracks, joints, and defects on the way in and pulls sand and soil out with it on the way out. Over time, this cycle hollows out voids behind the wall that nobody can see from the surface. Heavy rain speeds it up. Clogged weep holes and vents make it worse, trapping pressure that has nowhere to go except through the wall itself.

By the time a sinkhole appears in the yard or a section of wall visibly leans, the soil loss behind it is usually already extensive. Wall age, soil type, drainage, and storm exposure all affect how fast this moves, which is why two similar-looking walls can be at very different stages of failure.

Do Nothing, Patch It, Replace It, or Repair It Right

The instinct with a small crack or minor void is often to wait. But seawall damage compounds. A problem that starts as a localized void becomes a larger stability issue as soil continues to migrate.

The right path depends on how far the damage has progressed and whether the wall itself is still structurally sound. A proper site evaluation, not a guess from the yard, should always come first.

Why the Right Contractor and the Right Material Matter

Not every repair method is right for every wall, and this is where a lot of homeowners get burned. Some contractors default to aggressive, rigid two-component foams because they're fast and inexpensive to install. On the wrong wall, especially one with limited structural capacity or a lot of existing movement, that rigidity and expansion force can do more harm than good. In some documented cases, an overly aggressive two-component fill has blown a wall completely out rather than stabilized it.

Alchatek factory-trained contractors are taught to match the material to the wall, using flexible, hydrophobic single-component resins for void fill and soil stabilization in most residential applications, reserving higher-density two-component products for situations where they're actually appropriate. Some of these resins are certified to NSF/ANSI 61 for contact with potable water, a specific, third-party-verified standard covering leaching and health effects, though that certification speaks to potable water contact and doesn't by itself confirm performance or safety in a saltwater or marine setting. Confirm the specific certification for any product on its technical data sheet.

This is exactly why the contractor matters as much as the product. Filling a void and sealing the points of soil loss is only part of the job. Choosing a resin that fits the wall's condition, the soil, and the water environment is the rest of it, and that judgment comes from training and experience, not from a price quote.

Find a Trained Contractor Before You Have a Bigger Problem

Small cracks, soft spots in the yard, or a wall section that's slightly out of alignment are worth a professional look now, not after the next storm. An Alchatek factory-trained contractor can evaluate the site and recommend a repair matched to your wall's condition, rather than a one-size-fits-all fix.

Continue Reading

• Common Causes of Seawall Failure
• Signs a Seawall Is in Need of Repair
• Residential Seawall Repair

Seeing Signs of Trouble?

Small cracks, soft spots in the yard, or a wall section that's slightly out of alignment are worth a professional look now, not after the next storm. Talk to an Alchatek specialist at (404) 618-0438, or find a trained contractor near you.

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A long crack running through the floor of a high-traffic medical supply warehouse in Memphis signaled a problem below the slab. With forklift traffic and heavy racked storage running daily, and the building staying operational throughout, the team needed to know what was happening underground before choosing a repair method.

Initial Assessment

Ground penetrating radar (GPR) scans identified voided areas roughly 10 to 20 inches below the slab, confirming the crack wasn't just surface wear. Soil had shifted or washed out beneath the concrete, leaving sections of the slab unsupported. Removing and replacing the affected concrete would have meant disrupting warehouse traffic, adding downtime, and extending the repair window well beyond what the facility could accommodate on a live operating schedule.

Proposed Solution

Mid-South Concrete Lifting selected AP Lift 475, a two-component, high-density structural polyurethane, to fill the voids beneath the slab without removing any concrete. The product's expansion behavior, reacting to fill irregular void shapes rather than settling flat, made it a fit for reaching uneven cavities and re-establishing contact with the underside of the slab. This approach kept the facility in service throughout the repair.

Procedures

• Located the crack and mapped suspected void zones
• Staggered injection points along both sides of the crack
• Covered approximately 450 linear feet
• Drilled injection holes through the slab
• Injected polyurethane to fill the voids
• Monitored slab response throughout injection

Results

• Completed the project in two days
• Minimized disruption to warehouse operations
• Filled voids without slab replacement
• Improved support beneath forklift traffic areas

What This Means for Similar Projects

Void fill worked here because the slab itself was in good enough condition to stay in service and the underlying issue was a void rather than a structural failure in the concrete. That won't hold true on every job. Deteriorated or delaminated concrete, active water intrusion, poor bearing soil, or a drainage source that's still feeding the erosion can all change which repair approach actually makes sense. GPR or another subsurface assessment is generally the step that determines that, not the crack itself.

As a general point of reference, industrywide, full removal and replacement of an industrial slab tends to run well above void fill injection on a cost basis once demolition, disposal, and downtime are factored in. That gap varies by region, access, traffic control requirements, and the extent of the voiding, so it's not a number to lean on without a site-specific estimate.

The Role of a Technical Partner

This job was completed by Mid-South Concrete Lifting, a contractor experienced in polyurethane slab lifting and void fill work. On projects like this, Alchatek's role is providing the product knowledge and technical backup that help a contractor match the right polyurethane system to the void size, load, and site conditions, and staying available for tech support once the crew is on-site.

If you're weighing void fill, slab lift, or another repair method for a project you're looking at, Alchatek's tech support team can walk through the site conditions with you before you commit to an approach.

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Water infiltrated beneath spillway slabs at a campground, eroding soil and creating voids that cracked concrete. Leaks surfaced through cracks, threatening structural integrity. SiteMix Pressure Grouting, LLC was called in to repair the damage.

Initial Assessment

Probing revealed extensive voids beneath spillway slabs where water removed supporting soil and destabilized the structure. Traditional tear-out and replacement demanded extended closure, heavy equipment access, and prohibitive costs for this operational facility.

Proposed Solution

AP Lift 440 proved the perfect solution, featuring an 18x expansion ratio, 11,520 psf compressive strength for slab stabilization, and hydrophobic properties to prevent water infiltration.

Procedures

1. Established 4-foot grid pattern at lowest spillway area.
2. Drilled injection points through slabs.
3. Injected AP Lift 440 systematically across grid.
4. Monitored foam spread between injection points.
5. Completed both spillway sides plus access ramps.

Results

Completed repair in two days with zero downtime.
Stabilized slabs and eliminated all water intrusion with visible concrete drying confirming effectiveness.
Achieved approximately 65% cost savings compared to traditional concrete replacement while avoiding weeks of disruptive demolition.

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An Atlanta contractor contacted Alchatek for assistance with a void filling job in the parking garage at Brookhaven City Hall. The bottom floor of the garage exhibited significant voids beneath the concrete slab, posing risks of settlement and structural instability.

Initial Assessment

An Alchatek support technician worked with the contractor to conduct a thorough assessment and implemented a targeted void-filling solution to restore stability.

Proposed Solution

Alchatek recommended using AP Lift 430 Fast, a high-performance polyurethane foam designed for rapid void filling and stabilization. This material was selected for its quick-setting properties, high compressive strength, and ability to effectively fill voids while providing robust support for the concrete slab. The approach ensured minimal disruption to the parking garage operations, as it required no extensive excavation.

Procedures

1. Established a grid pattern to guide the placement of injection points on the bottom floor of the parking garage.
2. Drilled holes through the concrete slab at strategically determined injection points to access the voids beneath.
3. Injected AP Lift 430 Fast polyurethane foam into the drilled holes, ensuring comprehensive void coverage from bottom to top.
4. Patched drilled holes to restore the surface integrity of the concrete slab.

Results

The void-filling project at the Brookhaven City Hall parking garage was a success. The application of AP Lift 430 Fast effectively filled all identified voids, eliminating the risk of further settlement. The stabilized concrete slab restored the structural integrity of the garage floor, ensuring a safe and functional environment for vehicles and pedestrians. The solution minimized operational downtime and avoided costly excavation, preserving the facility’s functionality.

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After the removal of a wooden deck, dangerous voids under the brick pavers were revealed in a luxury apartment pool deck, threatening its integrity and safety. The property owner contacted Helicon, a trusted foundation repair company.

Initial Assessment

Subsurface investigation confirmed extensive voiding with no practical access for excavation during occupancy. Demolition/replacement would take weeks, cost tens of thousands, and the pool would need to be closed during peak season.

Proposed Solution

The contractor selected AP Lift 440 for its hydro‑insensitivity, ~15‑minute cure, and ~80 psi compressive strength. This material was ideal for increasing the soil's bearing capacity and restoring the pool to its correct state.

Procedures

1. Map the void locations using ground-penetrating radar and probing.
2. Establish an injection grid targeting the largest voids first.
3. Drill strategic injection ports through pavers to void spaces.
4. Inject AP Lift 440 to refusal using calibrated pressure monitoring.
5. Allow 15-minute cure
6. Seal injection ports and restore surface aesthetics.

Results

• Structural integrity fully restored with 1,200 lbs of AP Lift 440, filling all voids.
• Zero operational downtime; pool deck remained accessible throughout repair.
• Approximately 70-90% cost savings compared to demolition/replacement alternatives.

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A Tennessee state correctional facility had a significant infrastructure failure when newly installed plumbing beneath a concrete slab malfunctioned. In an attempt to address the issue, the original contractor backfilled the entire plumbing system with concrete. When this approach proved unsuccessful, a second contractor was brought in to demolish the concrete and properly repair the plumbing systems. This process left a substantial void beneath the slab that required immediate filling to restore structural integrity and minimize facility downtime.

Initial Assessment

Following the plumbing repairs, engineers assessed a void measuring approximately 200 square feet in area and 4-5 feet in depth, totaling roughly 800-1,000 cubic feet of empty space beneath the concrete slab. The prison's security restrictions severely limited access to equipment, making traditional concrete replacement a challenging and time-consuming process. The facility required a solution that would minimize disruption to operations while providing structural support equivalent to the original concrete base.

Proposed Solution

Working with Alchatek, Mid-South Concrete Lifting recommended using  AP Fill 420, a two-component structural polyurethane foam, to fill the substantial void. This approach offered several critical advantages for the correctional facility environment. The material could be applied through a simple hose system, eliminating the need for heavy concrete trucks and mixing equipment that would be difficult to maneuver through security checkpoints. The foam's rapid curing time would significantly reduce the project timeline, and its structural properties would provide adequate load-bearing capacity for the slab above.

Procedures

1. Security clearance and equipment inspection were completed to bring polyurethane application equipment into the facility.
2. The void was accessed through existing openings created during the concrete removal process.
3. AP Fill 420 was applied using a free-shooting technique.
4. Material application was monitored to ensure complete filling and proper expansion throughout the space.

Results

The void filling was completed in 3 hours versus an estimated week for concrete replacement. AP Fill 420 polyurethane foam successfully filled the entire void space and provided adequate structural support. Prison officials expressed satisfaction with the efficiency and minimal operational disruption, leading the contractor to look at another similar project at a different state facility.

The polyurethane approach delivered 65-75% cost savings compared to traditional concrete replacement when accounting for materials, equipment, labor, and reduced facility disruption. The accelerated timeline also eliminated the extended security coordination costs typically associated with longer construction projects.

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A fire station access roadway developed cracking from subsurface voids caused by storm drain seam gaps that washed out soil during heavy rain, threatening daily emergency operations and pavement integrity. Geotech specialists from Helicon were brought in to assess the situation.

Initial Assessment

CCTV and probing identified voids up to several inches beneath the asphalt and open joints along the drain, allowing soil migration. Excavation replacement was rejected due to weeks-long closure risk, higher cost, and potential future seam misalignment, making trenchless permeation grouting the viable path.

Proposed Solution

AP Fill 700 was chosen for hydrophobic, single‑component injection with very low viscosity, and adjustable cure, enabling soil permeation, joint sealing, and formation of a water‑tight bearing layer for traffic.

Procedures

1. Map defects and mark the injection grid along the pipe and pavement.
2. Drill ports; set packers to target joints and halo around pipe.
3. Inject AP Fill 700 to refusal, prioritizing seam sealing.
4. Permeate surrounding soils to fill voids and densify subgrade.
5. Monitor pressures/returns; adjust set times for water presence.
6. Verify with sounding/CCTV and traffic proof-load.

Results

• Restored structural support and sealed joints with zero operational downtime.
• Completion in days vs weeks.
• Approximately 95% cost savings compared to full excavation and pipe replacement.

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A property in Atlanta featured a multi-level parking structure with a split-level design. The upper-level parking area began showing signs of significant distress, with visible cracking and pavement deterioration. Investigation revealed that soil was actively migrating through a lower retaining wall of the parking structure, creating voids behind the wall and compromising support for the pavement above. The color change in the asphalt surface clearly marked the affected area, and the problem was getting progressively worse, posing both functional and safety concerns for vehicles using the facility.

Initial Assessment

Engineers determined that soil was passing through the precast concrete retaining wall that separated the lower parking level from the surrounding earth. Testing revealed substantial voids had formed behind the wall, primarily involving clay soils that had become soft and unstable. While the wall itself remained structurally sound, the continued migration of soil threatened to create more significant issues if left untreated. Traditional repair methods would have required extensive excavation and potential wall replacement, a prohibitively disruptive and expensive approach for an active parking facility. The challenge was stabilizing the soil and filling the voids without impeding parking operations.

Proposed Solution

Alchatek recommended using two-component polyurethane foam (AP Lift 475) to stabilize the soil and fill the voids behind the wall. This material was selected specifically because of its high compressive strength and ability to effectively fill large voids in clay soil conditions. Since the wall was precast concrete and structurally sound, there was no concern about the polyurethane's strength pushing or damaging the wall. The expansive properties of the material would ensure complete penetration into irregular void spaces, while its closed-cell structure would prevent future water migration that could cause additional soil loss. This approach would stabilize the subsurface conditions without requiring excavation or disrupting the facility's operations.

Procedures

1. Established a precise injection grid with tighter three-foot spacing in the first row close to the wall and slightly wider spacing in the second row.
2. Drove injection pipes through the soil to reach the void areas behind the wall.
3. Injected approximately 15 pounds of two-component polyurethane every 1.5 feet vertically, ensuring complete filling from bottom to top.
4. A hydraulic pipe puller was used to extract injection pipes during material placement for controlled distribution.
5. Monitored for any structural movement throughout the process using zip levels and dial indicators to prevent over-pressurization.
6. Injected material systematically across the affected area, adjusting quantities based on observed soil conditions.

Results

The project successfully halted soil migration through the retaining wall and stabilized the pavement above. The two-component polyurethane effectively filled all voids while creating a waterproof barrier to prevent future erosion. Most importantly, the solution eliminated the need for disruptive and costly excavation, allowing the parking structure to remain operational throughout the repair process. Post-treatment monitoring showed complete stabilization with no further signs of settlement or cracking in the pavement. The property owner avoided significant reconstruction costs that would have been incurred with traditional methods, while also preventing potential revenue loss from parking facility closure. This case demonstrates how polymer injection technology can provide effective structural solutions with minimal operational impact, a key consideration for commercial property remediation.

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The US Army Corps of Engineers (USACE) required a solution to fill the annular spaces between eight 84-inch ductile iron pipes and the concrete bulkhead at a new pump station along the Mississippi River in Port Sulphur, Louisiana. Traditional methods, such as pouring non-expanding resin, were cost-prohibitive (approximately $50,000 per void) and lacked the necessary performance characteristics. The voids posed a risk of instability and water infiltration, demanding a material that combined strength, adhesion, and environmental safety.

Initial Assessment

Inspections revealed significant annular gaps around the pipes, necessitating a material that can bond to both ductile iron and concrete while forming a waterproof seal. The USACE prioritized a solution that avoided excavation, minimized downtime, and provided long-term durability. Based on the scale of the pipes and typical annular space requirements, the voids were estimated to range from 6 to 12 inches in width around each pipe, although exact dimensions would depend on site-specific conditions.

Proposed Solution

Alchatek’s AP Lift 430, a high-density, two-component polyurethane foam, was selected for its compressive strength of 7,200 psf, ensuring structural support while adhering tightly to both ductile iron and concrete. Its hydrophobic nature prevents water infiltration,  and its expansion capability allows for complete void filling without precise volume calculations. AP Lift 430 provided a balanced solution for strength, durability, and cost efficiency.

Procedures

1. Material Application: AP Lift 430 was free-sprayed into the annular spaces using a Graco Fusion spray foam gun, ensuring deep penetration and adhesion to both the ductile iron pipes and the concrete bulkhead.
2. Curing and Expansion: The foam expanded to fill the voids, creating a seamless and waterproof barrier.
3. Surface Finishing: Excess foam was ground flush with the concrete surface to allow secure installation of flanges and gaskets.

Results

The project was completed in two days, with no disruptions to ongoing site operations. AP Lift 430 formed a durable, watertight seal, meeting all USACE requirements for strength and longevity. Total material costs were approximately $30,000, representing a 90% cost savings compared to other resin-based alternatives. The USACE supervisor conducted daily inspections and praised the efficiency and quality of the repair.

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A Utah-based geotech specialist partnered with a general contractor to address a critical DOT infrastructure challenge involving the replacement of an existing culvert on a major roadway in Utah. The project involved the installation of precast concrete slabs on both sides of the box culvert, designed to create a seamless transition from the culvert to the compacted road base.

Site Investigation and Challenge

During the design phase, engineers identified that constructing a compacted road base beneath the slab would inevitably leave voids underneath. These voids posed a risk of uneven support and potential rocking of the slab when subjected to heavy traffic load.

Proposed Solution

To address this, ¾” holes were drilled four feet apart to allow for injection rods to be inserted through the slab. The foam selected for this slab was AP Lift 440 structural foam due to its rapid expansion and high strength needed for DOT projects. This foam expands 17-19 times its original volume within 8-10 seconds of injection, ensuring comprehensive void filling. Dial indicators were used to ensure that there was no vertical movement of the slab during the injection process.  

Results and Conclusion

The entire operation was executed in approximately three hours, utilizing about 400 lbs of structural foam. This successful application filled all of the voids, providing uniform support for the precast slabs and enhancing overall road stability. The rapid curing properties of the foam allowed for swift project completion with minimal disruption to traffic.

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