Septic drain field failure

My earlier septic tank cleaning did not work.  Thursday morning water seeped out of the tanks' lids as after last week's work I had not shoveled the dirt back over the tanks in order to wait and see if the drainage problem returned.

*sigh*   It looks to be a problem with the drain field. Not good.

Once the ground thawed in the early afternoon I got a shovel and set out to dig and find the drain field pipe.  I am quite proud of myself that I found it quite quickly.  The PVC pipe was inches away from the hole I originally dug.  It was a pretty good calcuated guess as to where the pipe was over 20' away from the septic tank.  The pipe doesn't go straight out of the tank as it had to turn to miss the patio.

Once I found the pipe I started digging to see if I could find an area with a mass of tree roots around the pipe  - the likely cause of the problem as two large box elder trees are relatively close.  I didn't find any.

I was surprised to find a number of small pieces of long dead tree roots in the ground above the pipe.  It appears that when the pipe was laid in the 1980s dirt and roots all were pushed back into the trench to cover the pipe.

I also ended up digging up some of the alfalfa plants growing above the pipe.  The alfalfa has very long roots.  The roots went down deeper than the pipe.  Several alfalfa plants I was able to dig around without slicing through the roots.  I will be interested if the alfalfa continues to live as large sections of the roots were exposed during the day.

I kept following the pipe to the west.  I did this partly in hopes the end would have a cap at which I could enter the pipe from a direction other than from the septic tank.  Also I was curious at how far the drain field went to the west.  I half expected the drain field to be small considering the soil is porous and dad could have skimped on the size when he had it fixed/redone in the 1980s.

I found the west end of the line was a "T" connector with pipe going to the north and south. I found connections for side pipes all along the east/west pipe.  I eventually found 8 side pipes.  I have no idea how long these side pipes were.  All total I estimate the drain field size to be 220' feet of pipe if the side pipes were the same length as the one side pipe I dug out.

The "T" connector did not have a cap or access in order to run a snake from that side.

It was dark by the time I dug out the east/west pipe.  I had dug out 45-50 feet of pipe.

Friday - once the ground thawed late morning - I dug 20' away from the main line at where I guess the side pipe would end.  I was right once again.

I took the cap off and found a small amount of very dry stuff along the bottom of the pipe.    I ran a small snake into the pipe and found it to be blocked fifteen to sixteen feet away.  In other words the first four to five feet of the pipe from the main line was blocked.  I had to dig out the entire length of the side pipe.

Once that was done. I removed the two 10' sections of pipe.  The four feet or so of one pipe was clogged with fine tree roots that had entered in a number of the small holes running along the bottom of the pipe.  The fine tree roots acted like hair clogging a drain.

Small holes on bottom of the pipe

Once I cleared the roots out of the pipe I turned my attention to the main pipe.  The "T" connector was mostly clear of roots.  I had thought the blockage was to the right .  The problem was how to remove the pipes from the middle and not from the ends.

I found the pipe had enough give for me to lift it high enough so that the end came out of the "T" connector.

I found the right pipe had some roots in it covering the bottom half.  I cleared them from the pipe.

I found the left pipe was where the clog was located.  A foot from the connector was the clog. The pipe was completely blocked for a distance of about four to five feet.  It took a lot of effort to remove the tree roots.  Some roots had grown large enough to fill the hole they entered the pipe.

I ran a snake into the rest of the pipe I could reach (most of the east/week pipe and one side pipe) and didn't find any more tree roots.  I was sure the roots I had removed were the problem and I didn't want to dig up any more pipe.

Confident I had fixed the problem I began to shovel the dirt back into the trench to cover the pipe.  I got the side trench filled and a little of the main trench filled before dark.

I had read up on drain fields and it seems as if laying the pipes on a bed of gravel was the way to do it.  There were lots of rocks under the pipe but dirt had filtered in over the years.  If Winter wasn't approaching with a weather forecast of snow on Saturday I wanted to finish this project.  Besides I had other stuff to get done before Winter is here for good.   I estimate the length of the drain field pipe from the septic tank until the blockage at a little over 20 feet.  Apparently this length was acceptable for just me.  Two people used enough water to be a little too much water.  So the 220 ft available now should be plenty of length for drainage even if the gravel bottom is not as robust as I would like it to be.  If it isn't good enough, the pipe will be easier to dig out next Spring.