Today we responded to a sinkhole that formed at an industrial warehouse in Cranbury, NJ, part of the busy 8A industrial corridor known for heavy tractor-trailer traffic and massive stormwater loads.
At first, the facility manager feared the worst:
“I think the 18-inch concrete pipe for the roof drains has a hole inside it.”
Because that pipe handles all the roof drainage, a failure would be severe — potentially impacting the building structure itself.
Before touching anything, we requested a full utility markout to ensure no electrical, telecom, gas, or private utilities were in the excavation zone.
We carefully opened the sinkhole and traced the void down through the pavement and stone base.
When we exposed the 18” reinforced concrete pipe, it was in perfect shape — no cracks, no separation, no joint movement.
The sinkhole was caused by something most facility managers never think about:
A piece of underdrain had been installed in the subbase
The soil separation fabric had deteriorated
Soil washed down into the ¾” clean stone
Voids formed
The pavement above eventually collapsed
This type of failure is incredibly common in older industrial parks across Cranbury, Dayton, Monroe, South Brunswick, and Robbinsville because:
Heavy truck traffic stresses the subgrade
Large roof drainage systems expel tremendous water volume
Many properties were built quickly during expansion cycles
Underdrain fabrics from the early 2000s/2010s degrade over time
Even a small sinkhole can lead to:
Tractor trailer tire blowouts
Yard logistics disruptions
OSHA trip hazards
Water infiltration that expands the void
Structural settlement if water migrates toward footings
Our repair process includes:
Removing all compromised stone
Installing new geotextile fabric
Rebuilding the subbase with compacted DGA
Reinstalling the underdrain correctly
Re-paving the surface course
When a sinkhole forms on an industrial property, guessing is the most expensive mistake a facility manager can make. That’s why we use a structured, forensic-style approach to determine the actual cause before any repairs begin. First, we initiate a full utility markout to protect underground services. Once the site is cleared, we excavate a controlled area to expose the layers beneath the pavement — the asphalt, the stone base, the geotextile fabric, any underdrain components, and finally the storm pipe itself if one is present. By examining each layer in sequence, we can immediately see whether the failure came from soil migrating through deteriorated fabric, voids forming in clean stone, a separated pipe joint, improper backfill, or long-term water infiltration. This systematic process eliminates assumptions, prevents unnecessary pipe replacement, and ensures the repair is engineered to address the true root cause — not just the visible surface damage.
There is almost no online education for logistics property managers about:
How underdrains actually work
Why soil migration happens
What causes sinkholes beneath asphalt
How to differentiate pipe failure from subbase failure
How to avoid unnecessary excavation or camera work
Most contractors don’t understand drainage systems — and that leads to bad advice, misdiagnosis, and wasted money.
This article and video exist to provide real-world transparency for the 8A corridor.
If your warehouse, trucking yard, or industrial property has:
Sinkholes
Sinkholes around catch basins
Ponding areas
Drainage failures
You can upload photos for a quick assessment.
📍 FixAsphalt.com — Industrial & Commercial Pavement Experts
Serving: Cranbury, Dayton, South Brunswick, Monroe, Robbinsville, Hamilton, Hightstown, East Windsor & the entire NJ 8A corridor. In addition, we service all of NJ for sinkhole diagnosis and repairs.
Most sinkholes in the 8A industrial corridor are caused by:
Underdrain failures (deteriorated geotextile fabric → soil migration)
Voids in subgrade from poor compaction or water intrusion
Aging storm drainage systems (pipes from the 1980s–2000s beginning to separate)
Roof drain discharge volumes that overload the subbase
Heavy tractor-trailer traffic stressing already weakened soil
Construction shortcuts taken during boom years of warehouse development
This region has tens of millions of square feet of logistics buildings built fast — meaning many drainage failures are starting to show up now.
No.
In fact, most sinkholes are not caused by broken pipes.
Common non-pipe causes:
Failed underdrains
Geotextile fabric deterioration
Washed-out subbase
Old trenches backfilled with clean stone instead of DGA
Long-term roof runoff in one concentrated area
Pipe failures do occur, but they’re not the #1 cause.
FixAsphalt.com uses a multi-step diagnostic:
Utility markout (811 + private utilities)
Small controlled excavation
Inspection of subbase, stone, geotextile fabric, and underdrain
Inspection of concrete/HDPE pipes for signs of mud being carried through the pipe
Moisture tracing and soil compaction checks
Most “mystery sinkholes” reveal themselves within the first 12–24 inches.
No — and this is the #1 reason failures reoccur.
If you do not:
Identify the source of the void and repair it
Backfill properly
Restore drainage
…the sinkhole will return, often within weeks or months.
Most industrial sinkholes take:
1 day for diagnosis and excavation
1 day for repair
1 day for asphalt, concrete or landscape restoration
Complex issues where pipes need to be replaced may require 3–5 days, depending on inspections, pipe replacement, and compaction requirements.
Sinkholes near structures require more caution, including:
Camera inspection of pipes
Verifying settlement has not traveled under footings
Checking that roof drain lines haven’t separated
These locations may require engineered backfill, grouting or controlled-density fill.
Yes — but only in certain situations.
Grouting is used when:
The void extends deeper than safe excavation allows
There are cavities beneath a slab or behind walls
Soil loss needs to be halted quickly
In logistics yards, grout is often used under:
Aprons
Dock slabs
Trailer staging areas
Prevention includes:
Ensuring underdrains have intact fabric
Yearly drainage inspections
Keeping roof drains free of debris
Re-routing concentrated roof runoff
Sealing cracks to reduce water infiltration
Pavement management planning every 2–3 years
(Based on typical pricing for Cranbury, Dayton, Monroe, South Brunswick, Robbinsville, Hamilton & the greater Exit 8A industrial corridor)
Most reputable commercial asphalt contractors require a minimum mobilization charge due to:
Bringing equipment to a secure industrial yard
Utility markout coordination
Crew time
Excavator/skidsteer transport
Expertise of the individual diagnosing the problem
$3,500 – $7,500
👉 If the sinkhole repair is small and straightforward, this mobilization fee often covers the entire repair.
Examples of repairs often covered under mobilization:
Small voids (1–2 ft deep)
Surface-level soil migration
Minor underdrain repairs
Minor pipe repairs
If the sinkhole is caused by:
A broken storm pipe
A separated joint
A collapsed section
Root intrusion
Joint displacement
…the repair cost increases significantly if the pipe can not be repaired/patched and has to be replaced.
$2,500 – $25,000+
(depending on pipe size, depth, access, and replacement length)
Factors influencing cost:
8", 12", 15", 18", or 24"+ pipe
Concrete vs HDPE
Depth (3 ft vs 10 ft+)
Working near building foundations
Heavy truck traffic zones
Need for trench boxes or shoring
If excavation is unsafe or voids extend too deep, grout is used to fill the cavity.
$2,500 – $5,000
(Depending on cubic yards required)
Used especially when:
The sinkhole is under a dock approach
There are voids under concrete slabs
Subgrade migration extends beyond the visible collapse
Typical subbase reconstruction costs depend on:
Depth of excavation
Soil removal
Bringing in new aggregate
Installing new fabric
Compacting in lifts
This is often included within mobilization unless the excavation is large.
After repairing the subbase or pipe, you must restore surface materials.
$8–$15 per sq ft
(Depending on depth and location)
$12–$20 per sq ft
$18–$28 per sq ft
$500–$3,000
(Topsoil, seed, grading restoration)
$85–$125 per linear foot
Often clients forget to budget for these post-repair restorations—but they are critical to leaving the site safe and usable.
| Repair Category | Typical Cost Range | Notes |
|---|---|---|
| Mobilization | $3,500–$7,500 | Covers simple sinkhole repairs |
| Pipe Replacement | $2,500–$25,000+ | Depends on material, size, depth, access |
| Grouting (Void Injection) | $2,500–$5,000 | Used when voids too deep or under concrete slabs |
| Subbase Rebuild | Included or $1,500–$6,500 | Depends on excavation size |
| Asphalt Restoration | $8–$15/sq ft | Deeper repairs cost more |
| Concrete Restoration | $12–$28/sq ft | Depends on thickness & load rating |
| Landscaping/Topsoil/Seed | $500–$3,000 | Final grading & restoration |
| Curb/Gutter Repair | $85–$125/ft | Common on truck aprons |