burying the mainline

[alanandpat]

is keeping the mainline buried a good idea in Northern VT?

[BreezyHill]

I don't have an answer just my observations from southern VT/NY border bush.

This season I added a very low mainline. It skims thru at 12" off the ground for a distance of about 300'. It was a bit of an issue as it was buried in about three feet of snow for a while. I understand snow is an insulator more than soil is so take this with a grain of salt. I ended up needing to get it out of the snow as it was freezing sap in the line. After it was uncovered no issues. It is more susceptible to radiational warming from the ground due to its height but not much I can do unless I add another ladder. This is an option but I will give it another season before I do that.

If the line remained buried I would have lost production on 200 taps until the line thawed which was very late in the day. Nothing more confusing than pulling slush into the glass manifold and releaser at 2 in the afternoon when things thawed out at 10 am. But I went searching the next day and found the issue...felt really stupid I didn't look there first. But not 200' away is another main that was also in the snow for a short distance and that never caused an issue.

So I guess it will depend on how long the buried length is and how much frost you get. If below frost line then I don't see an issue and it may actually help cool the sap on those hot days but if average ground temp is 48-52 then on a good part of the season you will be elevating your sap temp. Then you need to factor in having to blow the line down to keep it from freezing before it freezes.

Good Luck!

Ben

[GeneralStark]

It is only a good idea of you treat a buried mainline as you would a buried waterline. If it is going through a field you should go at least 4' deep. Through a wooded area you could go more shallow, but in a cold year with no snow the frost can go deep in the ground. The primary issue, as Breezy described above, is if the mainline is flowing sap through 32F ground or snow, the sap will freeze.

Many folks do it, but I know of two situations where they did not go deep enough and they have had significant reductions in productivity due to freeze up.

The other things to consider are what type of pipe you use, as once again it should be treated as a buried waterline, and how you backfill the trench. We used sand to backfill all our waterline trenches here to minimize damage from frost movement.

[eagle lake sugar]

There was a 20.000 tap operation near here that had I think a 3" buried mainline. He continually was having to have it thawed while losing production, so I would say no. Frost was 8' deep this year, one extra potential problem.

[markcasper]

[QUOTE=BreezyHill;282751Then you need to factor in having to blow the line down to keep it from freezing before it freezes.

Good Luck!

Ben[/QUOTE] What exactly do you mean here? I would like to bury about 2000 feet to get sap to the road and now am having second thoughts if its going to warm it to 50 degrees. I ran out 1400 feet this spring just laying on top of the ground because I got stuck. Needless to say I will be doing it again because it worked so well. I had a 1000 gallon tank on a trailer down by the road and the dump tank is 600 gallon. At times when it was warm, I'd wait til nightfall when it was cooler and then start letting the sap flow across the fields and it actually cooled the sap quite a bit.

[BreezyHill]

Ground temp below the frost line is in the range of 48 to 52 degrees....check your water from your well as to a base reading in your area.

Your sap flowing thru a buried line is going to have the temp affected by the soil surrounding it. The same way that the air temp and sun affect lines above ground. Warmer days warmer dap, sunny days warmer sap than on cloudy days.

When we get end of season is when I really start walking around and checking mainline temps to see where I need to change over to wet dry lines first on single line designs. On the warm end of season days I was recording temps of 55 and 58 on cloudy 60 degree days. If the sun was out it was higher than air temp by a couple degrees and usually not over 4 degrees.

Check out the design needed for buried pipe for geothermal heating a house. In my area a neighbor needed to bury a line 1000' long to get the water warmed back up to soil temp to go back into the house for efficient heating of his home. In clay soil it was less distance. He is in a gravely area and need extra distance.

My warmest main was the main closest to the ground on sunny days even though it is blue. It is next to a trail that lets extra light in and warms from the heat radiating from the ground.

In the same fashion if you covered your on ground main with leaves or allowed Mother Nature to do the work you would see a cooling affect since the ground is usually frosted while we are running and the leaves will insulate the sun's heating affect to some extent.

So at 1500' of line in the ground you should have sap coming out near to what your well water is coming out at...that is unless you are on municipal water that can be different depending on the system design. But our area had a boat load of frozen mains and the frost was past the 6' deep mains in the first part of March.

I was planning to use my brook that freezes my mains near it to cool sap by wraping pex pipe around one of my collection tanks and adding insulation around it. One three checks of the water temp it was from 42 to 45 degrees. That is fine for end of season but wont work for early season for those 36 degree days with sap coming in at 38 and cooling to 34 in tanks that are in cold parts of my building.

If I didn't explain well enough let me know. Got to run

Ben