As we all know, water flows downhill. Starting with your slab in the brewery, water flows into the drains, to the piping under the slab, then out to sewer or in to an underground tank. Let’s talk about that underground tank for a bit.
The world is your oyster. This can tank be big or small, concrete, fiberglass, plastic, steel, or..? There is no right or wrong, but there is good, better, and best for sure. Read here for an blog post about a brewery lift station.
Thoughts on size. Go with the biggest tank you can afford and that you have room for, especially if you have a production brewery with plans to grow over the years. Big tanks have more headspace, and that headspace can be used when things aren’t going right- such as a pump or power failure. The headspace can fill a bit before alarm level, and before water starts backing up in the drains. Having space available allows you to at least finish what you were doing.
A small tank works, but there isn’t much room in the tank. If the pump fails or power goes out the tank will fill and back up in the drains quickly. It’s also a tight fit for accessory equipment such as level sensors, junction boxes, and any sort of strainer. Bigger is better.
Materials of construction. I really like using quality plastics in wastewater applications, they doesn’t corrode and they’re usually inexpensive. However, due to high temperature and potentially very high temperature underground plastic tanks (prefab septic tanks) should be avoided for a brewery. In normal circumstances the water will be pushing the upper temperature limits leaving your brewery, averaging about 105F or so. Most underground plastic tanks are rated for no higher than 120F. There will also be spills and other events leading to water that can be close to 200F in that tank. A collapsed wastewater tank because of an overflowing hot liquor tank would be a major bummer.
What I do normally use is a precast concrete tank. Temperature is never a problem, they’re inexpensive and readily available. A urethane coating inside the tank, or an anti-corrosion admix in the concrete helps. Admixes are a whole new world, but for this discussion it’s a material added to the wet concrete and mixed in, making the concrete itself inhospitable to bacterial growth (and corrosion).
Fiberglass tanks are OK, but susceptible to temperature and corrosion. To match those concerns a special resin needs to be used, making the tank a special order. And fiberglass tank manufacturers aren’t widespread, so shipping gets expensive. I have looked into offering a custom, prefrab, fiberglass brewery wastewater tank package, but it simply gets too expensive.
A steel tank is asking for trouble due to corrosion. Stainless steel is an option, but it’s expensive and nothing is readily made for an underground, direct burial application.
Ugh. All of this and we’re still on underground tanks…