The freeze plan

The one thing, if you read nothing else

48 hours out

1. Walk the site and mark each container IN or OUT with tape or chalk. Write it on the container, not on a list.
2. OUT: open the valve, drain fully, leave the valve open and the lid loose.
3. IN: fill to the moulded line. Not above it — you still need expansion headspace.
4. Disconnect every hose, drain it and coil it indoors.
5. Remove, drain and store every pump. This is the single most expensive item you will lose.
6. Check that heat trace circuits actually energise. Test them now, not at 2am.

The night before

1. Insulate every valve body. A jacket, a wrap, a bucket of straw taped over it — anything that traps air.
2. Lag any pipe run you could not drain, and lag it at the low points first.
3. Move anything portable indoors or into the lee of a building.
4. Close the array's isolation valves so a single failure cannot drain the whole system.
5. Photograph the setup. If you do have damage, you will want the before picture.

During the event

• Do not run a pump against a frozen line.
• Do not apply flame, heat gun or boiling water to HDPE. It softens near 175 °F.
• Do not stand on or lean a ladder against a container. Cold HDPE is markedly more brittle.
• If a valve must be thawed, wrap it and pour warm water over the wrapping. Patience, not temperature.
• Leave it alone otherwise. Most freeze damage happens during well-intentioned intervention.

On the thaw

1. Inspect every valve before opening it. A cracked body will look fine until it is under head.
2. Open valves slowly, with a bucket underneath, the first time.
3. Walk the sidewalls with a torch in raking light. You are looking for bright white lines — stress-whitening from ice load. Those containers come out of service permanently.
4. Check the top radius of anything that was full. That is where a surface skin pushes against the lid.
5. Re-prime pumps only after confirming the line is clear end to end.

If you find damage, photograph it before you touch it. We are happy to look at pictures and tell you whether a container is recoverable, whether or not you bought it from us — that offer is open to anyone and it costs us nothing but ten minutes.