Underground cold storage · Operator notes
Notes from inside a freezer
built in a limestone mine.
I run an underground freezer in an old limestone mine. This blog is where I write down what I learn: freezer operations, temperature records, maintenance, and what underground storage is actually like day to day.
*From my own operation. Your site will differ.
Who this is for
Cold storage operators
People running freezers, coolers, or dry warehouses who want practical notes on logs, maintenance, and keeping temperatures under control.
Businesses shopping for storage
Food producers, distributors, and brands comparing cold or underground storage and trying to figure out what to ask.
The underground-curious
Anyone wondering how a 120-year-old limestone mine ends up holding freezers, and why the rock helps.
Latest posts
Installing Racking in a Running Freezer: The Contractor Rules I Learned the Hard WayIn summer 2025 a crew installed drive-in racking in our new freezer room while the refrigeration was running. It took longer than planned, a door got left cracked to the outside, and half the units got switched off. Here are the rules I'd set before the next crew walks in.
Free Water Isn't Free: Our Underground Lake Is Hard WaterWe have an underground lake right on site, so why not feed the cooling towers with it? The lab results said hard and alkaline, and our water treater still prefers city water. Here's the trade-off, explained with cycles of concentration.
Phantom Shutdowns: The Level Probe That Read 38% on a Column Well Past Half FullOur compressor room kept shutting down and the graphs showed nothing. The cause was a high-level safety: a probe reading low, a float doing its job, and an alarm that wasn't set up right. Here's how we found it and what to check first.
Retro-Commissioning an Ammonia Plant: The Rules of Thumb Worth StealingOur refrigeration plant went through a utility retro-commissioning study. Here are the rule-of-thumb savings it used for head pressure, suction, staging and defrost, how the study actually ran, and what to check before you touch a setpoint.
Brine Valves That Cycle 20+ Times a Day: Why Ours Leaked at the PackingOur actuated brine valves flip between cold and warm brine all day. About a year in, they started leaking at the stem. Here's what we learned about specifying and spare-stocking them.
Myth: Caves Are Naturally Freezing. What the Rock Does (and Doesn't Do) for an Underground FreezerUnderground rock sits around 58 °F, not below zero. An operator explains where the cold in an underground freezer really comes from, what the rock gives you, and what it doesn't.
What's coming
- Underground vs. above-ground cold storage: where the costs differ
- What to do when a freezer goes down at 2 a.m.
- FSMA rules for storage-only warehouses, in plain English
- Freezer evaporator icing: causes and fixes
- Humidity and condensation in underground storage
- Questions to ask before you rent cold storage space
Get the free temperature log template
Get the free cold storage temperature log template, plus new posts by email. It's a printable sheet and CSV for daily freezer and cooler checks. See the template. No spam, unsubscribe anytime.
Follow along via RSS.