16 October 2026 Uncategorized 0

Manhole Core Drilling in Australia: No Entry Without a Permit

Manhole core drilling is high-risk construction work, so before any bit touches the wall, you need a SWMS, a confined-space permit and a documented atmospheric test. Run the rig wet with a continuous water feed, capture the slurry with a wet vacuum, and fix a hydraulic or electric rig to the structure. If any of those controls is missing, stop and call a licensed coring contractor.

TL;DR:

Keep the gas monitor running throughout drilling, record readings and test times on the permit, and assign an attendant outside the chamber.

Use continuous water delivered to the cutting face and a wet vacuum to capture slurry; a spray bottle or garden hose is inadequate.

Scan for utilities and reinforcement, verify the structure, then drill a pilot hole; stop and escalate if it reveals an obstruction or mismatch.

Confirm the boot or sleeve diameter and manufacturer’s tolerance before drilling, then measure the finished opening and test watertightness under expected pressure.

Use a licensed coring contractor for large diameter holes, confined chamber entry, complex sealing, or work requiring authority approval before crews or equipment are committed.

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For manhole penetrations and other concrete coring work, Vicsawing provides core drilling services across Melbourne and Victoria.

Explore core drilling

When side-wall coring is the right way into a manhole
What to complete before you drill
Confined-space controls that apply to manholes
Choosing the rig, bits and setup
Step-by-step side-wall coring procedure
Slurry capture and dust control
Sealing the penetration and finishing the opening
Fixing common coring problems fast
Where an in-house crew should hand over to a specialist
Hiring a coring team for manhole work
FAQ
Sources

When side-wall coring is the right way into a manhole

Side-wall coring lets you create a new opening in an existing chamber without excavating the whole structure. That is why it suits trenchless work, where the goal is to connect or pass services with minimal surface disruption. Before you commit to it, check the site against these common uses and constraints:

Service entry and exit: new incoming pipes, outlet relocations and access points for trenchless crews.
Trenchless pipe connections: a cored opening gives the pipe a clean, round, close-tolerance seat for a boot or sleeve.
Internal fittings: steps, ladders, existing inverts and benching limit where the rig can sit and how large the hole can be.
Invert level and flow: the new opening needs to sit above or clear of live flow, and the benching shape decides how the mast can be braced.
Wall thickness and reinforcement: thick or heavily reinforced walls change the bit choice, the feed rate and the time on site.

As a quick test, side-wall coring is usually the right call when the opening is round, the wall can carry the rig’s reaction load, and you can reach the cutting face with a secured mast. If the opening needs to be rectangular, the wall is structurally doubtful, or the chamber is too small to brace a rig, another access method may be safer. If the chamber is also hard to enter, our notes on concrete drilling in tight spaces cover the setup problems you will meet.

What to complete before you drill

Paperwork comes first because it decides whether the job can legally start. Work through this sequence in order:

Prepare a SWMS. Treat the coring as high-risk construction work and document it in a safe work method statement that covers the confined space, the silica hazard and the plant being used. If you are unsure which safety document your site needs, this guide to SWMS versus JSA requirements explains the difference.
Raise the confined-space permit. A manhole that looks dry is still a confined space, and the permit must be in place before anyone enters.
Locate services. Scan the wall and surrounding slab for electrical conduits, reinforcement and other utilities, then mark the position.
Verify the structure. Compare the position against drawings, or get an engineer’s sign-off for the penetration. Large contractor standards also require a permit for any penetration into concrete and a pilot drill to confirm the core location, as set out in one major contractor’s penetration standard.
Obtain authority approvals. Where the chamber belongs to a water or sewer authority, get written approval before you modify it.
Coordinate with the principal contractor. Agree the exclusion zone, the isolation of flow if any, and who signs off the finished opening.
Plan the next trade. If pipe installation or relining follows the coring, confirm the opening size with that crew. Specialists such as Priority Plus Plumbing handle relining of cracked or misaligned pipes, and agreeing tolerances early avoids a second cut.

The competency standard behind this work, unit CPCCON3057, expects the operator to select and set up the coring system, set out the hole with correct measurements and calculations, and work within WHS and environmental requirements. If your operator cannot show those skills, the job is not ready to start.

Confined-space controls that apply to manholes

A dry-looking manhole is not a safe one. Hydrogen sulfide and methane can be present without any visible sign, so WorkSafe guidance requires atmospheric testing and a documented entry permit before entry. Apply these controls on every job:

Test the atmosphere: check oxygen, hydrogen sulfide, methane and other toxic gases before entry, and keep monitoring while work is under way.
Record the results: the permit should show the readings, the time and who took them.
Ventilate: use forced ventilation to keep air moving, and keep intakes clear of vehicle and generator exhaust at street level.
Choose the power source carefully: hydraulic and electric rigs avoid the exhaust that a petrol engine puts into an enclosed chamber.
Control silica: silica-containing materials such as concrete release hazardous dust when cut, so follow Safe Work Australia’s silica guide, which prescribes wet cutting and local exhaust ventilation as engineering controls.
Select respiratory protection: wear RPE suited to the exposure, fit-tested to the person wearing it.
Keep records: retain the permit, test readings, exposure controls and equipment checks with the SWMS.

Where enclosed-space work and silica exposure overlap, as they do inside a chamber, controls at the source matter more than protective equipment worn afterward. Our own guidance on wet versus dry cutting explains why wet methods come first.

Pro Tip: Leave the gas monitor running for the whole drilling period and assign one person outside the chamber to watch it. A clean reading at one point says nothing about how the air may change later.

Choosing the rig, bits and setup

In a confined chamber, hydraulic and electric rigs are the working choice, and internal-combustion engines are avoided because their exhaust can quickly deplete oxygen. Set up the rig in this order and check each point before you start:

Mounting: use a drill stand or mast with anchor bolts into sound concrete, and follow the manufacturer’s instructions for fixing. The industry standard for safe concrete cutting and drilling requires secured drill stands with anchor bolts.
Bit selection: match diamond core bit diameter and length to the hole and the wall depth. Manufacturers publish the diameter ranges commonly available for manhole work, as in this diamond core drill range, and they reference the close tolerances that seal installation depends on. Our note on how deep you can core drill concrete helps when wall depth is in question.
Couplings and fitment: quick-change couplings speed up bit changes, but confirm the bit seats true before every start.
Water feed: supply continuous, multi-feed water to the cutting face. The industry standard also calls for feeding tap water into the hole to flush slurry.
Electrical safety: use IP-rated equipment, check safety tags, and confirm RCD protection on every lead.
Slurry extraction: connect a wet vacuum to the water feed so slurry is removed as it forms, and fit overfill protection to the vacuum pump.

Heavy in-plant machines are a different category. Production machines such as the Core-Matic and the Hydrokor III are built for factory throughput with multiple spindles and heavy hydraulic power, so they do not represent what you will carry down a shaft. On site, the field rig is the one you can brace, power and extract from safely.

Step-by-step side-wall coring procedure

Follow this sequence for each opening, and stop at any step where the result does not match the plan:

Mark the hole. Set out the centerline and diameter from the approved position, checking measurements twice.
Drill a pilot. A pilot hole confirms alignment and can reveal hidden reinforcement or services. If something unexpected appears, stop and escalate.
Secure the mast. Install the anchors, tighten the stand and check for movement by hand before connecting power.
Barricade and prepare water. Set up barricades, connect the water feed and confirm the wet vacuum is working.
Start in low gear. Begin slowly so the bit seats without wandering, with water already flowing.
Increase feed gradually. Raise feed pressure as the bit takes hold, keeping the cutting face cool with continuous water.
Manage torque. If the motor labors or the rig shudders, ease the feed and check for binding before continuing.
Release the core safely. Support the plug before it frees, since it can drop or jam, and remove it with proper handling.
Cover the opening. Protect any open penetration temporarily so no one can fall or drop material through it.
Check and document. Measure the hole against tolerance, prepare it for the boot or sleeve, and record the work against the SWMS.

Pro Tip: Count on the core plug being heavy. Rig a sling or catch plate before the bit breaks through, so the plug is controlled the moment it releases.

One more rule from the industry standard deserves repeating: do not drill inverted holes with electric drills unless they are fitted with a water-collection ring. Water running back toward the tool is an electrical hazard as well as a mess. Our overview of core drilling techniques adds detail on feed control and bit behavior.

Slurry capture and dust control

Water delivered to the cutting face is the first line of defense, and it has to be continuous. Safe Work Australia is clear that dry cutting without extraction or water suppression produces very high exposures, and a handheld spray bottle or a garden hose does not meet that need. Use these practices on every job:

Multi-feed water: deliver water directly to the cutting face for the whole run, not intermittently.
Source extraction: a wet vacuum removes slurry before it dries, which prevents respirable silica becoming airborne again.
Pump placement: position the pump where it stays accessible and cannot be flooded, and check intake screens during the job.
Pump maintenance: keep spare filters on hand and empty the tank before it reaches capacity.
Clean-up: wash down and vacuum residue at the end of each session so dried slurry does not become dust underfoot.
Disposal: collect and dispose of slurry in line with environmental requirements, never into stormwater or the open sewer.

Silica warning: Safe Work Australia states that dry cutting, grinding or polishing silica-containing materials without appropriate extraction or water suppression generates very high exposures. Wet methods are the baseline, not an upgrade.

For extra detail on reducing airborne dust, see our tips on minimizing dust when sawing concrete and how we capture dust at the source.

Sealing the penetration and finishing the opening

A cored opening is only finished when it holds water out. Trenchless connections need design verification that the seal will stay watertight under the expected hydrostatic pressure, as trenchless installation guidelines emphasize. Work through these checks:

Match boot to core: choose a boot or sleeve sized to the cored diameter, and confirm the seal manufacturer’s tolerance before you drill.
Check the hole: measure the opening and clear any chips or slurry film from the wall so the seal bears on clean concrete.
Grout correctly: where grout is part of the design, fill the annulus fully and let it cure as specified.
Test the result: confirm watertightness with a pressure or leakage check suited to the hydrostatic conditions on that line.
Protect and reinstate: guard the opening until the pipe is placed, then restore benching, step access and the surrounding surface.

If the finished opening misses tolerance, fix it before the pipe goes in. A boot forced into an oversize hole will not seal, and the repair costs far more than a careful measurement.

Fixing common coring problems fast

Most problems on a manhole job trace back to water, anchoring or surprises in the wall. Use these corrective steps:

Vacuum loss or clogging: isolate the pump, clear the lines, and swap filters. Keep spares and an overflow plan so slurry never reaches the chamber floor unchecked.
Excessive vibration or binding bit: stop and check anchors and alignment first. Then reduce the feed rate or change to a different bit profile.
Obstruction after the pilot: stop work, notify the principal contractor or utility owner, and have an engineer assess before cutting further.
Water in the wrong place: if water or slurry tracks toward electrical equipment, cut power and reposition leads and collection before resuming.

Do not push through any of these. An unexplained change in how the rig behaves is information, and the pilot hole exists precisely to deliver it early.

Where an in-house crew should hand over to a specialist

Our team works from a safety-first approach to manhole coring, and our view is blunt: the line between in-house capability and specialist work is drawn by risk, not pride. Call a licensed coring contractor for large-diameter holes, any entry into a confined chamber, complex sealing, or any job that needs authority approval. We are glad to assess the complexity of your site and provide a quote before you commit crews and plant.

— MYBMC

Hiring a coring team for manhole work

When the permits, the confined space and the sealing all sit on one job, handing it to a specialist removes most of the compliance load from your site. Our core drilling service is built around that:

Licensed operators: qualified crews who work to OH&S safety standards on commercial and industrial sites.
Wet slurry containment: we focus on safe, quality outcomes.
Confined-space discipline: we work with safety in mind.
Core drilling: we provide core drilling for your project.

We focus on safe, quality outcomes for your project. To request a site visit or a quote, contact us through our concrete drilling page.

FAQ

What does it mean to core a hole?

Coring a hole means cutting a cylindrical opening with a hollow diamond bit, which leaves a solid plug of material called the core. It produces a clean, round, accurate hole, which is why it suits manhole walls where a boot or sleeve must seal tightly.

What is the best way to drill a hole in a cement block?

Use a diamond core bit or a masonry bit on a rotary drill, and suppress dust with water where the material contains silica. For a manhole wall, secure the rig to the structure first, because a loose rig will bind and wander.

What are three types of drilling methods?

Three common concrete drilling methods are rotary hammer drilling for small holes, diamond core drilling for clean round openings, and rock drilling for harder ground. For manhole side walls, wet diamond core drilling is the standard choice because it controls dust and holds tolerance.

What are the available sizes for core drilling?

Diamond core bits come in a wide range of diameters, and manufacturers publish the ranges used for manhole coring. Pick the size from the pipe and the boot or sleeve specification, then confirm that the rig and wall depth can handle it.