Setyr worked example — WP-1 Wave Pool — Caisson and Pump Vault Isolation Not approved for use. Version 1 · 2026-09-25
Worked example only — your site must author, review and approve its own
procedure under 29 CFR 1910.147(c)(4). setyr.com/procedures
WP-1 Wave Pool — Caisson and Pump Vault Isolation
Aquatic attractions
Maintenance inside a wave pool caisson and pump vault. Covers the pneumatic blowers that generate the wave, surge chamber stored pressure, entrapment at the pool interface, and the chemical dosing lines that keep running.
This is a worked example, not a procedure you can adopt. It describes equipment that does not exist, with illustrative tag numbers.
29 CFR 1910.147(c)(4) requires the employer to develop, document and
utilise energy control procedures specific to their own machines, and (c)(6)
requires the employer to inspect those procedures periodically. Neither duty
can be delegated to a vendor or discharged by this document.
Isolation points
| # | Tag (illustrative) | Type | Disposition | What it does and why | Dwell |
|---|---|---|---|---|---|
| 10 | WP-1-POOL-CL | Block | Apply & verify | Pool closure and physical barriers at the water surface above the vault. Caution: The public do not know there is a crew under the pool floor. Closure is part of the isolation, not housekeeping. Confirm the pool is closed to the public and barriers are in place. Must remain in place. | — |
| 20 | WP-1-BLOW-1 | Disconnect | Isolate & lock | Wave blower number one motor disconnect, 200 hp. Caution: The wave sequence runs unattended on a timer. A blower that is stopped is not a blower that is isolated. Open, lock, prove dead at the starter. | — |
| 30 | WP-1-BLOW-2 | Disconnect | Isolate & lock | Wave blower number two motor disconnect, 200 hp. Caution: Both blowers must be isolated. The sequencer alternates between them and will select the one that was left available. Open, lock, prove dead at the starter. | — |
| 40 | WP-1-SEQ | Breaker | Isolate & lock | Wave sequencer and programmable controller supply. Caution: Isolating blowers without the sequencer leaves a controller that will energise valves and dampers on schedule. Open and lock the controller supply. | — |
| 50 | WP-1-SURGE | Vent | Isolate & lock | Surge chamber pressure relief and vent to atmosphere. Caution: The surge chamber holds pressure after the blowers stop. Opening the hatch against residual pressure launches it. Open the vent and lock open. Confirm the chamber gauge reads zero before opening the caisson access hatch. | 240s |
| 60 | WP-1-DAMPER | Block | Apply & verify | Caisson discharge damper between the surge chamber and the pool. Caution: An unpinned damper drops under its own weight into the caisson the crew is standing in. Drive the damper closed, pin it, and confirm the pin is seated. Must be ENGAGED. | — |
| 70 | WP-1-CIRC | Disconnect | Isolate & lock | Pool circulation pump disconnect feeding the vault suction. Caution: Circulation suction at the pool floor is an entrapment hazard for anyone in the water above the vault. Open and lock. | — |
| 80 | WP-1-SUCT | Valve | Isolate & lock | Vault suction isolation valve at the pool interface. Caution: The pool is full and above the vault. This valve is what stands between the crew and the pool volume. Close and lock the suction valve. Confirm the vault will not flood from the pool side. | — |
| 90 | WP-1-CL2 | Valve | Isolate & lock | Chlorine and acid dosing lines passing through the vault. Caution: Dosing lines run at pressure through the vault. A line broken during work sprays concentrated chemical in a confined space. Close and lock both dosing valves, then bleed the injection lines at the sample port. | 120s |
| 100 | WP-1-DRAIN | Drain | KEEP ENERGISED | Vault sump drain and dewatering pump. Caution: A vault below pool level takes water in. The dewatering pump is what keeps it survivable. Do NOT isolate. Confirm the dewatering pump is running and the sump is clear before entry. | — |
| 110 | WP-1-VENT | Breaker | KEEP ENERGISED | Forced ventilation into the caisson and vault. Caution: Chlorine vapour and CO2 collect in the low point of the vault. Do NOT isolate. Confirm continuous ventilation for the duration of the entry. | — |
| 120 | WP-1-GAS | Breaker | KEEP ENERGISED | Atmospheric monitoring at the vault floor and on each entrant. Caution: This is a permit-required confined space under 1910.146. Monitoring is the entry control. Do NOT isolate. Confirm calibration is current before entry. | — |
What your site must supply
- Your own asset and isolation-point tag numbers. The tags shown are illustrative and refer to equipment that does not exist.
- The actual location of every disconnect, valve and vent on your equipment.
- Measured stored-energy magnitudes and the dwell time required to dissipate them.
- Your verification method for each point, and who is authorised to perform it.
- Any additional energy sources present on your equipment and absent here.
Authorship and validation
This example was authored by Setyr for domain validation. It is not derived from any customer's controlled documents. It illustrates the elements 29 CFR 1910.147(c)(4)(ii) requires a procedure to contain — it does not certify compliance, which is a property of an employer's programme rather than of any document.