Out of sight, out of mind. We bought this house when it was about two years old, nearly twenty-five years ago. For the most part, the septic system works, so I don't pay any attention to it. But in December, there was an occasional whiff in the air. Indoors. So being promptly on the spot, a month later I called in the specialist, thinking it might need to be pumped, like we had done many years before.
He walked around, poking a metal probe into the ground, locating the dimensions of the tank that had long been completely buried. His face showed increasing unease as he puzzled it out. In one place, the probe had gone through deeper than it should have. He pulled out the shovel and exposed the two access ports on the top. One side was 'rotting' away. The concrete was easily a third thinner on the outflow side of the tank than the intake side. The concrete crumbled in his hand.
What had been a simple pumping job now became ten times more expensive. First off, I was warned most strenuously not to drive my tractor over the area. He had seen these situations before and even riding mowers were too heavy in many cases, and you do not want to have to fish your tractor out of the septic tank.
It was clear to me that the lid had to be replaced, although he was struggling to come up with cheaper solutions. Unfortunately all of those just were just delays, not fixes. As he dug more and exposed the surface of the lid, it was clear that the formerly flat slab was bowing down in the middle. The concrete's strength was fading away and it was only held in shape by the internal rebar steel rods.
Decades old septic tank lids aren't an off the shelf item. He took dimensions and some company somewhere poured and cast a new one. Wait two weeks. Don't walk on the septic tank.
Then came the day. It had to be Monday because rain was in the forecast Tuesday and the heavy trucks couldn't get across the yard without bogging down if the ground was wet. Carefully tensioning the chains, the crane operator lifted the old lid off and transferred it to the trailer. Everybody was holding their breath, hoping it wouldn't crumble and fall into the tank. Nobody wanted that clean-up job. Up in the air, the distorted, sagging of the concrete was plain to see.
Then, they put a gasket down around the edge and lowered the new, flat, and thicker septic tank lid in place. Now, a couple of days later, there's just a slight mound that needs reseeding and some ruts in the grass where the trucks passed. But its fixed, at least for a few more decades.
I asked why the concrete decayed like that. The guy with the experience wasn't sure. Perhaps water softening. Perhaps the chemicals given off in the air gap. All he knew was that the corrosion always happened on the outflow side of the tank. I'm just happy to forget about it. Out of sight, out of mind.
