Problem

The homeowner in Flushing noticed a sinkhole beginning to form near a concrete walkway where a downspout discharged rainwater into an underground PVC drain pipe. They believed the drainage system had already been inspected and was working properly.

Our senior project managers visited the property to perform a detailed inspection.

After examining the area, we discovered that the underground PVC pipe was likely cracked beneath the concrete slab. Instead of carrying rainwater away from the home, the damaged pipe was allowing water to leak directly into the soil.

Over time, the leaking water washed away soil surrounding the concrete. This created underground voids that caused the ground to settle. If left untreated, the voids would continue to grow and could eventually lead to a much larger sinkhole, cracked concrete, and possible damage to nearby structures.

Our Solution

After identifying the source of the problem, our team developed a repair plan that fixed the damaged drainage system while minimizing demolition.

Our work included:

• Carefully saw cutting the concrete around the affected downspout.
• Excavating only the necessary area to reach the damaged pipe.
• Using a tunneling method beneath the existing concrete whenever possible. This reduced unnecessary concrete removal and helped preserve the surrounding surface.
• Removing the damaged PVC drain line where repairs were not practical.
• Installing a new underground PVC drain pipe.
• Connecting the new pipe securely to the existing drainage system.
• Testing the drainage system to ensure water flowed away from the foundation correctly.
• Backfilling and compacting the soil to reduce future settlement.
• Pouring new reinforced 4,000 PSI concrete to restore the surface.

This approach allowed us to repair the drainage system while keeping disruption to the homeowner’s property to a minimum.

Why This Repair Was Important?

Repairing the damaged underground downspout pipe early helped prevent a much larger and more expensive problem. As water leaked from the cracked pipe, it slowly washed away the soil supporting the concrete slab, creating underground voids that led to settlement and sinkhole formation. 

By replacing the damaged pipe and restoring proper drainage, our team stopped further soil erosion, prevented the sinkhole from growing, and protected the concrete from additional settling. Most importantly, the repair helped keep excess water away from the home’s foundation, reducing the risk of future structural damage and moisture-related issues. 

Why Homeowners Should Not Ignore Sinkholes?

Even a small depression near a downspout can be a warning sign that water is washing away soil beneath the surface.

As soil disappears, the concrete above loses support and begins to crack or settle. In some cases, water can also migrate toward the home’s foundation, increasing the risk of basement leaks and structural movement.

Finding and repairing the source of the leak is much more effective than simply filling the hole with soil or replacing the concrete.

Need Professional Drainage Repairs in Flushing, NY?

If you notice sinking concrete, soft spots in your yard, or water collecting around your downspouts, Zavza Seal can identify the cause and provide long-lasting repairs that are code-compliant. Our team specializes in underground drainage repairs, concrete restoration, and foundation protection throughout Flushing and the surrounding areas.