....and should they be covered or not?

I suspect they are some type of inspection access.

When did they or do they get used?

Thanks.

Thats the end of your trench. Should be covered and if everything goes right they don't get used.

Ya what ST said.

Statistically, their should be four finger/trench’s. What happens is each trench is used for about 5-7 years, depending on you septic usage. Again, statistically the first trench to be used is the one the left of the four trenches, with your holding/ leeching tank to your back. What happens is the first trench is used, until is it saturated to the point of no drainage. Then the system moves to the second trench and so on. You should get about 20-30 years of usage out of a drain field.

Now, the end caps (these are the four tubes sticking out at the end of the trench, the forward tubes can be buried) are used for cleaning in some cases, but more so for inspection on how the system is working.

I knew the guy very well who installed my drain field and he installed a vent cap on my first trench, which I will move in a couple years (or until I see down the tube how the trench is doing) to the next trench.

The other tubes up by the holding and leeching tanks are for clean out. I was told to clean these tank out by a septic company every 3 or so years during the spring time. By doing it during the spring time, helps generate the bacteria growth over the summer for less chance of a freeze out during winter.

I have some V.H.S. footage of my drain field being installed if anyone wants to see it .


P.S.

If you burry any of the tubes, silicon a large steel washer to the top of the cover for the tube, so you can find it easy with a metal detector.


Good luck!

How does the system move to the next trench?

The first one stops draining so things back up and start flowing down the second trench?

"How does the system move to the next trench?"

My system is on a hill with the trenches at different elevations. Between the trenches and tank are drop boxes. Everything flows to the bottom trench. If that trench become saturated the water moves to the next higher trench.

Gotcha.

Thanks guys.

Your highest elevation trench line is the one that will be used first if the distribution box was installed correctly. Idea is once the bio-matt (layer that builds up on rock below distribution pipes) will eventually not allow effluent/water to seep through your rock at a fast enough rate to stay in front of what is coming from the tanks. Once this happens effluent/water can't get out of the distribution pipe and backs up into the distribution box filling it up slightly to a point where it can then flow out another port down to the next distribution box out the distribution pipe for that trench and the process starts over again.

If effluent ran to the lowest trench first and had to back up to the next higher one so on and so forth there would be seepage to the ground surface at the lowest trench location prior to the higher trenches being used as obviously there would be constant pressure from gravity forcing water into the lowest trench. This is typically how you would know that a trench system is lived out it's life.

Now to the original question...Assuming you are talking a trench system things where rather covered by the above posts. Just inspection pipes for the homeowner and or inspectors needs. Inspector being needed typically is the home is going up for sale and/or if a bedroom addition is planned (in most locations).

On my system the tank itself has 2 4" pipes coming up from the ground, and 4 small end caps on the ends of the drain lines. The 4" pipe on the end of the tank has a filter in it that needs to be cleaned out a couple times a year. Wouldn't hurt to take off those caps to check and see if there is a filter. Ya don't want that filter getting too plugged.

Pipes coming up from the tank are over the inlet and outlet ends. Usually 6" if there is a filter as it makes it easier to remove for cleaning but I guess not in your case. Recommend in spring and fall the filter gets pulled and sprayed off. Ones on the end of the drainfield line are as explained above. All can be cut off at ground level so that you don't have to mow around them, just over them. I wouldn't cover with dirt so that you know exactly where they are.

If you do cover with dirt and have a metal detector, I have found Pipes at my parents many times but siliconing a 3" steel washer to the pipe cover. Good little tip I learned years back from a local septic guy.