About

An operator-run blog about underground cold storage

I run an underground freezer in the Valmeyer bluffs, an old limestone mine on the Illinois side of the St. Louis metro. We also handle cold and dry storage.

Most of what you'll find online about cold storage comes from one of two places: facilities selling space, or software vendors selling software. I wanted something different: notes from someone who actually deals with the freezers, the logs, and the maintenance.

The mine

Limestone mining in these bluffs started more than 120 years ago, mostly for fertilizer. Parts of the mine were later used to grow mushrooms, from the late 1930s into the early 1980s. During the Cold War it was considered as a civilian defense shelter. Now it holds freezers.

A few things that stand out from running it (from my operation, not general rules):

• The rock sits around 58 °F year-round, which takes a lot of load off heating and cooling.
• Freezer setpoints vary by room, from about −15 °F to 8 °F.
• Solid stone pillars roughly 50–60 ft apart, with an average roof span of about 45 ft between them. The roof is bolted 8–10 ft deep.
• Once frozen, the rock columns act like giant ice cubes, which helps hold temperature if the power goes out.
• Being under solid rock keeps us out of tornadoes, blizzards, and storms.

What I'll write about

• Temperature logging, records, and plain-English compliance notes
• Freezer and refrigeration maintenance
• How underground storage differs from above-ground buildings
• What to ask if you're shopping for cold or dry storage

Ground rules for this blog

• When I share numbers from my own operation, I'll say so. Your building, product, and equipment will be different.
• Regulatory content links to the primary source, like the eCFR, FDA, or USDA. It isn't legal advice.
• No made-up case studies or testimonials.

Questions or corrections? Email info@decent4.com.