Above Ground vs Underground Storage

I know I should boil as soon as possible to prevent bacteria growth but I only have the ability to boil once or twice a week. So my question deals with sap temperature. Am I better off with a storage tank above the ground or below the ground? Above ground sounds good when the temp is cold but gets iffy when the temp rises (I am shaded but late season temps are still high). Below ground seems like it would offer a consistent temp. The question is what is that temp? Will the heat in the ground provide too much heat that it will encourage bacteria growth? Where will sap stay the coolest over a couple days, above or below?

As long as it stays below 30 degrees it will be fine but I would only wait a couple of days to boil but if u have snow on ground just pile it around your tank and it will stay cool if u have no snow then a tarp in a shaded area will help

I've heard of people freezing milk jugs full of water and when it gets warm out, just throw them in your tank! just like ice in a glass... but without the watering down effect! I've built little snow banks around my storage last year and that seemed to help quite a bit!

Keep in mind you should clean the tank periodically. Underground would present some challenges. Maybe you have this figured out
Temp wise, I think you are right on, tho.

I think you may want to do a little more research. Water from our well is 48 degrees from a stone lines dug well with at least 3' of concrete above ground and in this sub zero temps. 8 below this am. The deep well at 270 feet is 51 degrees. Geothermal in my area claims a soil temp of 52 at 6' year round. So you would need to have the tank open to cold air all winter long to get the ground to freeze around the tank. My sugar house is under a metal building and has 100% dirt on 1 wall and 1/2 coverage on north and south walls. east is all at grade level. It is nice to work in in the summer as it is very cool but the evap rig heats it up quick during sugar season. I am thinking of cooling sap with a heat exchanger using water out of our brook. Temps this year have been as low as 29 in the running water during last weeks fringed stretch. hard to get the thermometer out because I didn't trust what the noncontact meter said.

On my north side I have snow til nearly the end of season in the shaded area. I would take that route first as sap turns pretty fast in upper 40's.

Good Luck!

Sap tank buried in the ground would tend to warm the sap, not cool it unless you are in the frost layer of soil. Like BreezyHill said, once you get below 4-6 feet, the ground temperature becomes pretty consistant. The actual temperature will vary some in different locations, but it is usually in the upper 40 degrees to lower 50 degrees. Much warmer than you want your sap to be.

Never gave a thought to temp control when we put our 400 gallon bulk tank in a cellar hole next to sugar house , did it to make the drop work on our gravity lines without depending on a pump. 5 feet deep hand thrown stone walls about 12x12.solid rock ledge floor. Definately moderates the highs and low temp variations.

We put 2 gallon pails of sap in the freezer, then dump the sap cubes into the holding tank.
Nice and easy, fast and peasy.

What temperature is your sap after setting in the tank awhile.

It looks like underground might be a bit too warm. But what about above ground when the temp is in the 50 to 60 range. Is sap staying cool enough in the above ground tank?

Belted,
No, it doesn't stay cool enough, especially later in the season. That's why everyone tries their best to boil promptly.
I used to gather early in the morning, before work. You have the best chance of harvesting ice at that time. Helps, but not as good as getting it boiled. Is there anyone near you that would take your mid-week sap and boil on shares?

The temps get to 50 or 60 your season is either done or soon will be. However when the temps get in the mid 40s I will still have ice on the floor in cellar hole. As I said putting our tank in the cellar moderates the high and low temps.