Air Tools, Chisels & Core Drilling for Underwater Construction

Canada's infrastructure runs through water. Bridge piers cross rivers from the Fraser to the St. Lawrence. Dam structures manage watersheds from BC to Newfoundland. Wharves and marine terminals line thousands of kilometres of coastline and inland waterway. And all of it — at some point — needs to be built, maintained, repaired, or removed below the waterline.

Underwater construction is a specialized discipline where tool selection is as consequential as the engineering behind it. The wrong tool on a submerged concrete pier isn't just inefficient — it's a safety event in the making. The right combination of air tools, chisels and points, and core drilling equipment, in the hands of a properly equipped contractor, is what turns a complex underwater scope into a controlled, documented, on-schedule deliverable.

This article outlines the tools and methods that matter most for underwater construction and concrete demolition work in Canadian freshwater and marine environments, and how Madido supports commercial diving contractors and infrastructure owners across the country.

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Why Underwater Construction Demands Specialized Tooling

Surface construction is already complex. Add submersion — whether 3 metres in a turbid river or 30 metres offshore — and every variable becomes harder to manage. Visibility is limited. Diver fatigue is a real constraint. Tool changes take time that costs air and bottom time. And the consequences of equipment failure are not the same as on a dry site.

The tools used in underwater construction must be purpose-built or purpose-rated for subsea use. Standard surface tools introduce risks that cannot be mitigated by dive supervision alone: electrical hazards, lubrication leaching, seal failures under pressure, and ergonomic designs that are simply unworkable in a drysuit with gloves on. The Canadian standard CSA Z275.2 — Occupational Safety Code for Diving Operations establishes the baseline within which all commercial diving tool use must be evaluated.

Within that framework, three tool families do the heavy lifting on virtually every underwater concrete construction and demolition scope in Canada: pneumatic air tools, chisel and point attachments, and core drilling equipment.

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Pneumatic Air Tools: The Workhorse of Underwater Concrete Work

Pneumatic tools — powered by compressed air from a surface-supplied compressor — are the dominant tool class in underwater concrete demolition, scaling, and breaking. They are preferred over electric tools for two fundamental reasons: they produce no electrical hazard in a conductive marine environment, and they have no sealed hydraulic oil circuit to maintain at depth.

For shallow-water work — the majority of freshwater infrastructure jobs in Canada — pneumatic tools deliver the right combination of power, controllability, and diver familiarity. Surface diving supervisors control the air supply and can monitor output. The tools themselves are robust and service-friendly on site.

Pneumatic Chipping Hammers

The underwater chipping hammer is the equivalent of a surface-mounted breaker, scaled for diver use. These tools deliver high-frequency percussive blows — typically 1,500 to 3,500 BPM — through an interchangeable chisel or point. They are used for:

• Removing deteriorated concrete from bridge piers, pile caps, and abutments
• Breaking out spalled or delaminated sections of submerged slab and wall surfaces
• Scaling marine growth, barnacles, and bio-fouling from structural steel and concrete prior to inspection or repair
• Preparing surfaces for underwater grouting, epoxy injection, or patch concrete placement
• Fracturing and removing mass concrete in cofferdam or dam repair work

For Canadian underwater contractors, the selection between a light-duty chipping hammer (used for surface scaling and thin-section work) and a heavy-duty pneumatic hammer (for mass concrete and rock) is a project-specific decision driven by concrete strength, section thickness, and proximity to structural elements that must not be disturbed.

See here for Madido Chipping Hammer

Pneumatic Drills (Rotary and Hammer-Drill Mode)

Pneumatic rotary drills and hammer drills are used underwater for anchor installation, rebar drilling, sample boring, and preparatory drilling ahead of hydraulic splitting. Most purpose-built underwater models include pressure-equalized seals that maintain performance at working depth.

For infrastructure applications — drilling into a bridge abutment to install post-installed anchors, or boring into a dam face to install monitoring instrumentation — a pneumatic hammer drill gives the diver the control and feedback needed to maintain hole position and avoid deviating into rebar or post-tensioning.

See here for Madido Drills

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Chisels and Points: Selecting the Right Bit for Subsea Concrete

The chisel or point attached to a pneumatic chipping hammer is not a detail — it is often the variable that determines whether a scope runs efficiently or drags. Underwater concrete work demands the right bit geometry for the task, selected based on concrete strength, the removal goal, and proximity to material that must remain intact.

Moil Points

The moil point is the most aggressive bit geometry: a tapered, needle-like point that concentrates the full energy of the percussive blow onto a very small contact area. This generates extremely high localized stress — sufficient to fracture mass concrete, break out large chunks, and drive into hard substrates including rock.

Moil points are the standard choice for primary concrete demolition underwater: removing deteriorated pier caps, breaking out failed repair sections, demolishing mass concrete elements in decommissioning work. They are less suitable for work close to reinforcing steel that must be preserved, as the point's energy can damage rebar and embedded hardware if contact is made.

Flat Chisels

Flat chisels spread percussive energy across a wider blade edge — better suited for splitting along a defined plane, removing thin layers of spalled or delaminated concrete, and working close to edges that need to remain undamaged. In underwater concrete repair preparation, a flat chisel is used to square off a repair boundary, creating a clean perpendicular edge that will bond effectively with the patch material.

Scaling Chisels

Scaling chisels are wide, flat blades designed specifically for surface-layer removal: stripping marine growth, removing laitance from a concrete surface, and scaling away the carbonated or chloride-contaminated outer layer ahead of assessment or repair. On wharves, jetties, and sea walls where tidal action has degraded the surface concrete, a scaling chisel gives the diver control to remove exactly what needs to go without over-excavating into sound material.

Bull Points and Cape Chisels

Bull points are heavy, robust versions of the moil point used where maximum breaking force is needed — thick-walled structures, rock-adjacent concrete, and mass demolition work. Cape chisels have a narrow rectangular cross-section and are used for cutting grooves and chasing lines — for example, when a diver needs to cut a defined slot for a seal or joint installation in a dam face or intake structure.

Quick Reference: Chisel and Point Selection

Chisel / Point Type	Best Application Underwater	Use With Caution When
Moil Point	Mass concrete removal, fracturing, primary breaking	Working close to preserved rebar or embedded hardware
Flat Chisel	Splitting along planes, repair boundary prep, delaminated layer removal	Wide-area demolition — slow on mass concrete
Scaling Chisel	Marine growth removal, surface laitance, chloride-damaged layer removal	Thick or reinforced concrete — insufficient energy
Bull Point	Heavy-duty breaking in thick or high-strength concrete	Tight areas or near services — hard to control direction
Cape Chisel	Groove cutting, joint preparation, seal installation slots	General demolition — too narrow for efficient bulk removal

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Core Drilling Underwater: Precision Penetrations Below the Waterline

Core drilling — using a rotating diamond-tipped bit to cut a cylindrical hole through concrete, masonry, or rock — is as essential below the waterline as above it. In many underwater infrastructure scopes, it is the only method capable of delivering the accuracy and low vibration that the work demands.

Applications for Underwater Core Drilling in Canada

Bridge Piers and Abutments

Installing post-installed anchors, tie rods, and instrumentation cables in submerged concrete requires accurately located bores. Bridge rehabilitation projects on Canada's highway and rail network routinely include underwater core drilling as part of the repair scope.

Dam Structures

Dam repair, rehabilitation, and monitoring installation frequently require core drilling into submerged dam faces, aprons, and spillway structures. Bore location tolerances are tight — often ±10mm — and the structural sensitivity of a dam means that vibration control is not optional. Diamond core drilling delivers both.

Marine Terminals and Wharves

Pile cap repair, deck slab penetrations for drainage and utility routing, and anchor installation in submerged concrete cap beams all require underwater core drilling. Marine terminals across Canada's Pacific, Atlantic, and Great Lakes ports require ongoing maintenance drilling as their infrastructure ages.

Water Intake and Outfall Structures

Municipal and industrial water infrastructure — intake structures, outfall pipes, pump station wet wells — often requires drilling for sensor installation, pipe penetrations, and grout injection ports.

Material Testing (Core Extraction)

Extracting intact structural cores from submerged concrete for compressive strength testing, chloride profiling, and carbonation depth assessment. Test cores from submerged structures provide engineers with the condition data needed to assess remaining service life and prioritize repair spending.

How Core Drilling Works Underwater

The mechanics of core drilling do not fundamentally change underwater — a rotating diamond-tipped bit is pressed against the concrete face and advanced through it. What changes is the setup, flushing method, and operational constraints.

Surface water replaces the active water cooling used in above-water wet drilling, so bit cooling is generally not a limiting factor at normal depths. Slurry flushing, however, must be managed: cuttings generated during drilling will cloud the bore and reduce visibility unless the drill is equipped with an internal flushing port or a vacuum extraction system is used.

Drill rigs for underwater use are typically mounted on purpose-built frames that can be set against a vertical or horizontal concrete surface and secured — either by vacuum pad, mechanical anchor, or diver-held pressure. Stability is essential: an unstable drill produces oval bores, overheats the bit, and in worst cases walks off position and damages the surrounding structure.

Diamond Tooling Specification for Underwater Core Drilling

Not all diamond core bits perform equally in the subsea environment. The right bit specification depends on the concrete compressive strength (typically 25–50 MPa for Canadian civil infrastructure), rebar density, bore depth, and whether the work is in freshwater or saltwater.

• Segment type: Harder bond matrix for softer concrete; softer bond for hard, high-strength concrete. Getting this wrong dramatically shortens bit life.
• Barrel length: Standard 300–450mm barrels cover most wall and pier penetrations. Deeper bores require extension rod systems.
• Diameter: 50mm for instrumentation ports, 100–150mm for anchor and rebar bores, 200mm+ for large penetrations and sampling cores.
• Saltwater compatibility: Bits intended for marine use should have corrosion-resistant segments and barrel coatings. Standard freshwater tooling will corrode in extended saltwater use.

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Underwater Construction Project Types in Canada

Canadian infrastructure spans some of the most demanding aquatic environments on earth: fast-moving glacial rivers, tidal marine environments with significant fouling and corrosion, ice-affected freshwater lakes, and remote northern sites with short seasonal access windows. The tools described in this article are deployed across all of them.

Bridge Rehabilitation

Canada's bridge inventory is aging. The rehabilitation of concrete bridge piers, pile caps, and abutments below the water line is one of the most common underwater construction scopes in Canada. Pneumatic chipping hammers with moil points remove deteriorated concrete; flat chisels prepare repair boundaries; core drills install post-installed anchors for structural reinforcement.

Dam Repair and Inspection

Hydroelectric and water management dams require regular inspection and repair of submerged faces, aprons, and gates. Underwater concrete demolition using air tools and chisels removes failed sections; core drilling installs monitoring instruments and injection ports; pneumatic drills install grout tube arrays for void filling.

Wharf and Marine Terminal Maintenance

Tidal action, biological attack, and chloride-induced corrosion degrade submerged concrete at marine terminals faster than almost any other environment. Ongoing maintenance programs for Canada's port infrastructure include annual diving programs using the full range of air tools, chisels, and drills described here.

Water Intake and Outfall Structures

Municipal and industrial water infrastructure includes intake structures, outfall diffusers, and pump station wet wells — all of which require periodic maintenance and repair by commercial diving teams equipped with pneumatic tools and core drills.

Cofferdam and Dewatering Construction

Where underwater work requires a dry working environment, cofferdams are installed to isolate the work area. The installation of cofferdam sheeting, walers, and bracing — along with anchor drilling into the riverbed or harbour floor — involves all three tool categories.

Salvage and Underwater Demolition

The removal of submerged structures — failed sheet piling, sunken vessels, abandoned infrastructure, and collapsed culverts — requires underwater demolition using breaking tools and cutting equipment. For precision subsea demolition without explosives, pneumatic tools and diamond cutting are the methods of choice.

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Safety and Canadian Standards for Underwater Tool Use

All underwater tool use in Canada falls under the requirements of CSA Z275.2 — Occupational Safety Code for Diving Operations and the applicable provincial OHS legislation. For commercial diving operations, this means:

• All tools used underwater must be appropriate for the pressure conditions at working depth
• Pneumatic and hydraulic tools must not create a hazardous condition for the diver — including kickback, tool slip, or uncontrolled movement
• Air supply to pneumatic tools is managed from the surface and must not be interrupted without diver notification
• Electrical tools are prohibited in most underwater construction contexts due to electrocution hazard in conductive water
• Tool operation must be covered in the dive plan and pre-dive hazard assessment
• All diving operations must be supervised by a Diving Supervisor certified to the requirements of CSA Z275.4

For general contractors and infrastructure owners, the practical implication is simple: verify that your underwater construction contractor operates under a current, CSA-compliant diving safety management system and that tool selection is documented in the dive plan — not improvised on site.

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How Madido Supports Underwater Construction Contractors Across Canada

Madido is a full-service demolition and drilling contractor with the equipment, tooling, and technical expertise to support underwater construction scopes across Canada — directly and through supply partnerships with commercial diving contractors.

Equipment Supply

We supply pneumatic air tools, chipping hammers, core drill rigs, diamond tooling, and accessories to commercial diving teams who bring their own operators. We can configure a tool package to the specific requirements of your dive program.

Diamond Tooling

Madido stocks diamond core bits in the diameters and bond specifications required for underwater concrete — from small-diameter instrumentation bores to large sampling and penetration cores. We advise on the right spec for your substrate and can turn around orders Canada-wide.

Technical Consultation

Specifying the right tool for an underwater concrete scope is not always obvious. Our technical team has experience with the tool selection challenges specific to submerged infrastructure — high-strength marine concrete, heavily reinforced pile caps, silty or turbid water conditions. We can help you get the spec right before mobilization.

Nationwide Logistics

We operate across Canada. Whether your diving program is on the BC coast, a Prairie river crossing, or Atlantic offshore infrastructure, Madido can deliver equipment and tooling to your project location.

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The Bottom Line

Underwater construction in Canada demands the same technical rigour as any surface scope — and more. The tools are harder to use, the conditions are less forgiving, and the margin for error is narrower. Air tools, chisels and points, and core drilling equipment, when correctly specified and properly maintained, are what make complex underwater scopes executable.

Madido brings the tooling, the technical depth, and the national logistics capability to support your underwater construction program — whether you are a commercial diving contractor equipping a long-term infrastructure maintenance contract or an infrastructure owner managing a one-off bridge or dam repair.