The hard part of an emergency is that the decisions with the largest consequences get made first, when you know least.
This is an ordered sequence for the first two days. It will not fit every site. What it does is keep the options open and stop the common second failure, which is a hurried repair that has to be removed and done again.
Hour zero to two: safety and closure
Decide about the asset before anything else. Is the structure safe to carry load? A bridge with a scoured foundation, a road with a void beneath the lane, an embankment that has lost its toe — these are structural decisions and they belong to the engineer of record, not to the person with the excavator.
If in doubt, close it. Reopening a road is easy. The other outcome is not.
Make the site safe. Fast water, unstable ground, undercut banks, and voids you cannot see are the conditions in which people get hurt. See safety during emergency placement.
Notify. The asset owner, the engineer of record, and the agencies. That last one matters for permitting later — see emergency permitting.
Hour two to eight: find out what is actually happening
The most common expensive mistake is treating the visible damage rather than the mechanism.
Establish the mechanism. Is this scour at a structure, general bank erosion, a headcut arriving from downstream, or a slope stability failure that happens to be next to water? They look similar in the middle of an event and they need different responses. What is scour? covers the distinction, and contraction, local, and degradation scour covers which component you are dealing with.
Find out whether it is still going. Rising, peaked, or falling? Work placed into an active, rising event may not stay. Work placed on the falling limb has a better chance.
Probe rather than look. Water is opaque, the hole is underwater, and the bed may already be partly refilled with loose material. A rod tells you more than eyes do. See post-flood scour inspection.
Get the baseline if one exists. As-built elevations, previous soundings, the last inspection report. Knowing what changed is worth more than knowing what is there.
Photograph everything now. Debris lines, high-water marks, the extent of the damage. Perishable evidence, and it does double duty for the permitting follow-up and any reimbursement claim.
Hour eight to twenty-four: decide the intervention
Three questions in order.
Does anything need to go in now?
Sometimes the answer is no. If the structure is closed, the event is receding, and nothing is getting worse, the best move can be to wait for conditions that allow a proper repair. Emergency intervention has costs — it is expensive, it is done with poor information, and it may have to be redone.
Intervene now when: the damage is progressing, a further event is forecast, the asset cannot be taken out of service, or the next stage of failure is much worse than this one.
What is the minimum that arrests it?
Emergency authorisation covers what the emergency requires, and work beyond that is unauthorised work. It is also usually the work most likely to be wrong, because it was designed in a hurry.
Aim at stopping the progression, not at building the permanent solution — unless the permanent solution is achievable now, which is the next question.
Can what goes in now stay?
Worth asking early, because it changes what you place.
Armor installed to a standard a permanent design would accept is often the same work at the same cost. The difference is whether it was sized, extended past the affected area, and keyed at the toe and flanks the way a permanent design would be — the details in why scour protection fails.
If it can be done properly now, do it properly now. See can emergency work become permanent?.
Hour twenty-four to forty-eight: place it
Work from the outside in. Establish the edges of the protection first where you can, so the flow is not working at an unprotected boundary while you fill the middle.
Extend past the damage. The single most common defect in emergency armor is stopping at the visible hole. Flow then attacks the new edge, and you are back in three weeks. The affected footprint is larger than the hole.
Key the toe. If the bed is going to keep lowering, protection that sits on the surface will be undermined.
Do not narrow the waterway more than you must, particularly at a bridge, where contraction was part of the problem. The answer bank covers protecting an abutment toe without unnecessarily narrowing the opening.
Record as you go. Quantities, locations, what was placed where, who authorised it, and when. See documenting emergency work for claims.
What makes this go quickly
Almost all of it is done before the event:
- Knowing which sites fail, because most agencies do
- Materials pre-positioned, so response is a mobilisation rather than a procurement — see pre-positioning emergency stock
- Knowing who to call at each agency for emergency authorisation
- A baseline record for vulnerable sites
- Internal authority to commit, agreed in advance
An agency with those in place responds in hours. One without spends the first day finding out who to ask.
Where to go next
- Stabilizing a scoured abutment fast
- Repairing a washed-out road embankment
- Placing armor at flood stage
- What to send with an emergency request
- Emergency permitting
- The emergency hub for the rest
For an active emergency, call rather than use a form. The number is on the contact page.