BRH (hydraulic rock breaker): what the project manager needs to know about this earthworks equipment to avoid letting a geotechnical contingency go by with no contractual trace
The contractor informs you they are “required to use the BRH.” You hear a technical constraint. The right reflex: also hear a potential 2-week delay, an extra cost of tens of thousands of euros, and an immediate question — was this anticipated in the G2PRO geotechnical study, and if not, who pays for it?
Type | Phase | Actors | Impact | Stakes | Where |
|---|---|---|---|---|---|
Technical | Execution | Contractor, MOE (project manager), Client (MO), BET (structural/technical engineer) | High | contractual | earthworks / studies section of the CR |
1. Operational definition + common mistake
The Brise Roche Hydraulique (BRH, “hydraulic rock breaker”) is a demolition/excavation tool mounted on an excavator, used to break up rock, hard clay-marl, or buried concrete too hard to excavate with a standard bucket. Its use during earthworks indicates soil resistance greater than the contract’s baseline assumptions.
In this CR, the earthworks contractor (JME) discovered zones of very compact marl requiring the BRH. The G2PRO geotechnical study had anticipated its use, but the actual volumes exceed what was planned. Result: an estimated 2-week delay on the trade, and a knock-on halt for the special-foundations contractor.
Many assume the BRH is just another piece of site equipment like any other — in reality, as soon as a contractor announces they’re required to use the BRH on a volume not anticipated in the contract, it’s a signal of a potential TS / TSU (additional-works claim: equipment surcharge, slower pace, schedule impact) that must be documented, quantified, and processed through the quote → formal instruction (TS / TSU) procedure.
2. Where it appears
In a site meeting report — in the Studies or Site Tracking section of the Earthworks trade, when a geotechnical contingency is discovered. Typical wording: “The contractor flags the obligation to use the BRH,” “Use of BRH due to very compact marl.” Examples from this CR:
“The contractor alerts us that they are required to use the BRH. The volume is greater than anticipated in the G2PRO.”
“The contractor has commissioned a surveyor to measure these volumes.”
“Supply a detailed volume survey of materials requiring the BRH (cross-sections and plans)” — Obs.: PI, follow-up required
“The contractor has halted work due to difficulties encountered by the earthworks trade (Use of BRH due to very compact marl)”
3. How to read this entry in the CR
If you read “obligation to use the BRH” for the first time → immediately trigger two actions: request a survey of the volumes concerned (cross-sections and plans) and check whether the G2PRO anticipated this type of material and to what extent.
If the BRH volume exceeds the G2PRO’s forecasts → this is a contingency that can justify a TS / TSU. Request the cost estimate for the extra work, forward it to the client, and issue a formal instruction if approved.
If the BRH impacts the schedule → factor the delay into the master schedule, alert the client, and document the cause to preserve the delay’s non-attributability.
4. Who does what
Actor | What BRH means to them | Concrete action |
|---|---|---|
Earthworks contractor | A technical contingency to flag and quantify | Alert the MOE as soon as it’s discovered; commission a surveyor to measure the volumes; supply cross-sections and plans |
MOE / OPC | A contingency to assess, document, and process contractually | Check the G2PRO; request the detailed survey; trigger the TS / TSU procedure if needed; update the schedule |
Geotechnical engineer (BET Sol) | Assessment of the contingency against the studies | Confirm whether the contingency was foreseeable or is a genuine unforeseen event — affects the parties’ liability |
Client (MO) | Decision-maker on funding the extra cost | Approve or reject the TS / TSU; decide whether to accept the delay or compensate with acceleration |
5. What this changes in practice
A project manager who handles the BRH alert correctly can precisely quantify the extra cost, protect the schedule, and secure the TS / TSU process before the contractor invoices without a contractual basis. A project manager who lets a BRH go undocumented risks a late claim from the contractor with no way to verify the actual volumes.
Failure scenario: the contractor uses the BRH for 3 weeks with no survey or TS / TSU process triggered by the MOE. At the end of the project, the contractor invoices €80,000 in extra BRH costs. The MOE can neither confirm nor deny the volumes: a dispute is inevitable.
6. Example of real wording
“The contractor alerts us that they are required to use the BRH to carry out their works. The volume of earthworks requiring this equipment is greater than anticipated in the G2PRO.”
“The contractor has been halted since last Thursday due to difficulties encountered by the earthworks trade (Use of BRH due to very compact marl)”
7. Points of caution
The BRH isn’t automatically a TS / TSU: if the G2PRO anticipated it for the actual volumes, the contractor has no right to extra payment.
A BRH announced with no surveyor’s report can’t be quantified: require the volume measurements before approving any TS / TSU.
A BRH-related delay can trigger knock-on delays for downstream trades (special foundations, shell-and-structure) — document them all.
The G2PRO is the contractual reference: any gap between planned and actual volumes must be justified against this study.
Don’t confuse the BRH (hydraulic tool on an excavator) with a jackhammer (manual tool): the pace and cost implications are very different.
8. Not to be confused with
Related term | Key difference |
|---|---|
G2PRO | Geotechnical design study that anticipates contingencies — the BRH is often the consequence of a contingency not, or poorly, anticipated |
Additional works (TS / TSU) | The contractual framework for the BRH extra cost — the BRH is the technical cause, the TS / TSU is how it’s processed |
Jackhammer | Manual fragmentation tool — the BRH is a hydraulic, excavator-mounted version for much larger volumes |
Rocky ground | Nature of the soil — the BRH is the tool used to handle this ground, not a description of it |
9. Related terms
Same phase (earthworks/foundations): G2PRO · Additional works · BSD · Soil pollution · Special foundations
Same actor (contractor/MOE): Volume surveys · Intervention schedule · Delay in days · Geotechnical contingency
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