Excavate a spring by digging gently round and behind the eye until you expose where the water leaves the rock or soil, about 1 m back and 0.5 m below the emergence point, working with hand tools, from below upward, with the flow kept running in a channel. Wet ground is weak, so a cut deeper than 1.2 m must be sloped back at about 1.5 horizontal to 1 vertical or shored, and the spoil kept at least 0.6 m from the edge and never uphill of the spring.
Part of Spring Capture
Spring excavation is the hand digging that exposes the eye and makes room for the box. It is delicate, because digging too hard damages the spring, and risky, because the ground is wet and on a slope.
Dig To Expose The Eye, Not To Chase The Water
The aim is to see exactly where the water comes out of the rock or soil, and to clear enough room behind and below it for the box and its gravel. The Spring Capture guide gives the size as about 1 m behind the emergence point and about 0.5 m below it. Dig gently with a spade and by hand near the eye: a spring can be damaged by digging too aggressively, as the water finds a new path and the original eye dries or moves. Stop deepening when you find the impermeable layer the water is flowing on; cutting through it lets the water drain away.
Wet Banks Must Be Sloped Or Shored
The soil above a spring is usually wet and weak. Any excavation deeper than 1.2 m, the figure this guide uses (British Columbia occupational safety rules and Ontario guidance; US OSHA and Alberta use 1.5 m, and some others give no figure), needs sloped or shored walls. As a slope, soil that is saturated or has water seeping from it is classed as the weakest type, which US OSHA rules (29 CFR 1926 Subpart P, Appendix B, recalled here) cut back at 1½ horizontal to 1 vertical, about 34° from the horizontal.
| Face height | Horizontal setback at 1.5:1 | Working |
|---|---|---|
| Up to 1.2 m | None required | The threshold; below it a face may stand |
| 1.5 m | 1.5 × 1.5 = 2.25 m | Slope back or shore |
| 2.0 m | 2.0 × 1.5 = 3.0 m | Slope back, or bench and shore |
For a 2 m face, the wide cut is 3 m back from the foot on each unsupported side. Where there is no room, support the face with boards and props in place of a slope, setting the boards before anyone works below them. Check any wall after rain and stop work if it creeps, cracks at the top or runs muddy.
What You Need
- Hand tools — spade, trowel, small pick, bucket
- A temporary channel or pipe — to carry the flow past the work
- Boards and props — for shoring a face
- A diversion ditch dug first (Uphill Diversion)
- A tape and a level — to mark the eye and the planned floor
- A partner — nobody digs a deep cut alone
Method: Divert, Expose, Clear, Mark
Step 1: Divert surface water with the uphill ditch before you start.
Step 2: Expose the eye. Start downhill of it and work uphill, removing soil in thin layers. Use hands and trowel at the eye.
Step 3: Keep the flow running through a channel or pipe out of the work area, so the pit does not fill.
Step 4: Find the base. Dig until you see the impermeable layer the water flows on. Stop there.
Step 5: Mark the eye level with a stake and a level line. The overflow height will be fixed from it (Box Design).
Step 6: Put spoil away. Heap it downhill and to the side, at least 0.6 m from the edge, never above the spring, where rain washes it back into the water.
Step 7: Slope or shore any face over 1.2 m, and check it every morning.
Common Mistakes
- Spoil on the uphill side. It slides into the work and into the spring.
- Digging at the eye with a pick. The water moves.
- Working in the rain without a ditch. Runoff floods the pit and brings the bank down.
- Digging alone. Wet ground gives no warning.
Safety
Cave-in is the main killer in excavation
A wet face deeper than 1.2 m must be sloped back or shored; keep spoil at least 0.6 m from the edge; never work alone or below an overhang; and get out of the cut as soon as the wall cracks, creeps or runs muddy. Tools and rocks dropped into a cut injure the person in it. Cold water and long periods standing in it chill workers: rotate and warm up.
What’s Next
- Learn next: Box Design — choosing the box size and the overflow level
- Combine with: Uphill Diversion — keeping the pit dry