A well shaft kills in three ways: the walls collapse, the air at the bottom cannot keep a person conscious, and anything dropped from the top lands on the digger. Line every metre before digging the next, force air to within half a metre of the bottom for 20-30 minutes before anyone enters and keep it running throughout, put the digger on a harness and line tied to the hoist with two people above, and if the digger collapses haul them out from above, because most well deaths are rescuers who went down.
Part of Deep Wells
A well shaft is a confined space: a deep, narrow opening with one way in and out, in which air can change faster than a person can sense. This protocol covers the working rules for digging, lining and cleaning shafts, and the Phase 0 guide Well Digging applies the same rules to a first hand-dug well.
The Bottom Of A Shaft Can Hold Air That Does Not Support Life
Air is about 21% oxygen. Below 19.5% a person is already impaired, and the usual regulatory definition of an oxygen-deficient atmosphere starts there. A flame goes out below roughly 16%. A person is therefore impaired well before a flame would show anything, which is why a flame is no test: it can read “fine” while a worker is losing judgement, and it detects nothing of the poisonous gases below.
| Gas | Weight against air | Where it collects | Notes |
|---|---|---|---|
| Carbon dioxide | about 1.5 times as heavy (44 ÷ 29) | Pools at the bottom | Odourless; from soil, rotting matter, breathing; it displaces oxygen |
| Hydrogen sulphide | about 1.2 times (34 ÷ 29) | Low spots | Smells of rotten eggs at low levels but dulls the sense of smell at high ones, so loss of the smell is not safety |
| Carbon monoxide | about the same as air (28 ÷ 29) | Mixes through the shaft | Odourless; from engines, fires, charcoal; never run an engine or fire at the mouth |
| Methane | about half as heavy (16 ÷ 29) | Rises; collects under covers and in high pockets | Flammable and explosive; no flame, spark or smoking near the shaft |
Carbon dioxide and hydrogen sulphide sink; methane rises. A shaft can hold more than one. You cannot see or reliably smell any of the dangerous cases, so the rule is to ventilate every time instead of testing. A gas meter that happens to be salvaged is useful, and you still ventilate.
Never test the air with a flame, a lamp or a candle
A flame can ignite methane in the shaft. It goes out at about 16% oxygen when a person is impaired from 19.5%, so a burning flame is not evidence the air is breathable, and it tells you nothing about hydrogen sulphide or carbon monoxide.
Ventilation: Air Fanned Across The Top Does Not Reach The Bottom
Hang a cloth chute or pipe so that its open end is within half a metre of the bottom, and drive air down it with a bellows, a hand blower or a fanned board (Bellows Building). Air fanned across the mouth of a shaft stays near the top: the bad air underneath is undisturbed. Run the air for 20-30 minutes before anyone goes down and keep it running while anyone is below.
How long is enough depends on the shaft and the blower, so work it out. A shaft 1.2 m across and 10 m deep holds π × 0.6² × 10 = 11.3 m³ of air; at 15 m it holds 17.0 m³. If your blower delivers 30 L per stroke (an assumed figure; measure yours by filling a bag) at 20 strokes a minute, that is 0.6 m³ a minute:
- 10 m shaft: 11.3 ÷ 0.6 = 19 minutes to push one shaft’s volume of air through
- 15 m shaft: 17.0 ÷ 0.6 = 28 minutes
Air does not move through a shaft as a clean plug and the duct leaks, so one shaft volume is the least that can be needed. A shallow shaft with a good blower may be cleared in 20 minutes; a deep one needs the full 30, and more if the blower is weaker. Ventilate for longer if in doubt.
Collapse: Line As You Go, And Keep Weight Off The Edge
- Line before you dig on. Never dig ahead of the lining. The exposed unlined wall below the lining should never be taller than one section.
- Walls deeper than 1.2 m need support. Any excavation deeper than 1.2 m is sloped back or shored; a shaft is lined instead, and a wide cut for a platform or ring is sloped or shored.
- Spoil at least 0.6 m back from the edge, and the tripod and windlass feet on firm ground clear of it.
- Stop at the first warning. Trickling soil, new cracks around the edge, a wall that suddenly weeps or turns to mud, a ring that creaks or tilts: stop, haul the digger out, and make the wall safe before anyone goes back. Heavy rain, a blast or vibration from nearby work is a reason to stop and inspect.
Falling Objects: A Dropped Bucket Is A Missile
A 10 L bucket of wet soil weighs about 18 kg (0.01 m³ at an assumed 1,800 kg/m³). Dropped 10 m it arrives with 18 × 9.81 × 10 = 1,766 J, roughly 1.8 kJ of energy, onto whoever is below. Tools can do the same.
- Tools on lanyards, never loose in a pocket at the edge.
- Fill the bucket about two-thirds, and use one that cannot spill its load as it is lifted.
- Run the hauling line off to one side so it never passes over the digger’s head, and wear a hard hat or a helmet of leather or wood.
- Nobody leans over the mouth while someone is below. The attendants work the line from the windlass, set back from the opening and offset to one side. Raise the lining to stand above ground so tools kicked at the edge cannot fall in.
The Crew: Two Above, A Harness On, A Line To The Hoist
| Role | Does | Never does |
|---|---|---|
| Digger | Wears a harness (seat and chest, not a loop round the waist alone) tied by a line to the tripod; signals with the line | Enters without ventilation running; unclips the line |
| Line attendant | Tends the line and keeps it clear of snags; hauls on any sign of trouble | Leaves the line or goes down |
| Second person | Runs the blower, keeps it going, fetches help | Leaves the wellhead unattended |
Agree line signals before the first entry: for example one pull for “all well”, repeated pulls for “haul now”. Rotate the digger on a schedule so no one works to exhaustion; the Phase 0 guide rotates every 30-60 minutes.
Rescue: Haul From Above, Never Go Down
Never climb in after a digger who has collapsed
A person who collapses at the bottom did so because the air there will not support them, and it will do the same to whoever follows within seconds and without warning. Haul them out on the safety line, drive air into the shaft while you do it, and do not send a second person down because the first rescuer has also stopped moving. That is how one death becomes three.
If the line is fouled, or the digger is trapped in a collapse, the answer is still not to enter. Keep the ventilation going, add people on the line, and make the shaft safe from above. If a collapse has buried the digger there may be no way to reach them; re-entering to dig is then a new dig under the full protocol (ventilation, harness, line, two above, shaft supported), not a rescue. This is why the line stays attached below 2 m depth and why lining is never skipped.
Once out, a person who is breathing is laid on their side (Recovery Position); one who is not breathing needs CPR at once (CPR Technique). They need fresh air and rest even if they seem to recover.
Six Checks Before Anyone Enters The Shaft
- Chute or pipe within half a metre of the bottom; blower running for 20-30 minutes already.
- Harness fitted; line tied to the tripod; line free of snags and tested by a pull.
- Two people at the top; one on the line, one on the blower.
- Spoil at least 0.6 m from the edge; tools on lanyards; no engine or fire at the mouth.
- Lining complete to within one section of the bottom.
- Signals agreed. Stop conditions agreed: any dizziness, headache, shortness of breath, drowsiness or confusion means haul up at once. Drowsiness and confusion are late signs, after which the digger may not be able to climb out alone.
What’s Next
- Learn next: Lining As You Go — the lining sequence that keeps the walls up
- Combine with: Hand Digging — where this protocol is applied