Over the past week or so, as time permitted, we installed the septic system. I wanted to place the tank and drain field more toward the back of the lot, well away from the water well. But our lot is sloped from back to front, and you know the First Rule of Plumbing: That there stuff runs down hill.
The way most septic tanks are built here is this: Dig a big square or rectangular hole, pour a perimeter foundation at the bottom of the hole, lay up concrete block walls, pour a concrete floor, stucco the inside of the walls, pour a concrete roof, building in an access door for future tank cleaning and maintenance. The only problem with this approach is that any crack anywhere at all in the tank would allow ground water to enter, filling the tank, and unprocessed effluent to escape and potentially enter the water well. Additionally, we have a very high water table and it would be a real mess to work in all that water for a week or so.
So I bought a big, five-foot diameter, six-foot tall, 2,600 liter plastic tank. The tank is leak proof, plus it allows for very rapid installation. We thought that a six-foot diameter hole would be just about right to drop the tank in and then back-fill with dirt.
I stuck a piece of rebar in the ground about where I wanted the center of the tank. Then I loosely tied a piece of string to the rebar. I tied another piece of rebar to the string three feet away from the first piece. With Armando, Manuelito, and Abdiel standing by with shovels, I used the string and rebar like a big compass, walking the rebar around in a circle, scratching the ground, and the guys digging to mark the circumference.
The three of them started digging. But when the hole got about a foot deep it got too crowded; two of them kept digging there, and I got the third man started digging the drainage field a few feet away.
While this was happening I had four yards of crushed rock delivered for the drain field.
I also walked home and got a short stepladder, because the hole was beginning to be deeper than the guys are tall. At first the digging was quite easy. But at just below the three-foot mark, the guys hit a layer of yellow, hardpan clay. The clay got progressively harder as they dug deeper, and for the last two feet or so it was very slow going. Even with a pick axe it was inch by inch by inch.
But the guys finally prevailed, and at the end of a tiring day we dropped the tank in the hole and back-filled it as tightly as we could. The men really pushed to get the job done in one day; I reminded them that if we didn’t accomplish it in one day, then they would have to bail hundreds of gallons of water the next morning. I could see by the look on their faces that they didn’t relish the prospect of that job! Cynthia and I keep a supply of five-pound bags of rice on hand; they make a very good tip for the men on those really grueling work days.
The next day we finished digging the drainage field and spread the stone in the pit. I ran four-inch PVC pipe from the tank to the drain field. In the States, I remember using drain-field pipe that had holes drilled every few inches for drainage. But that product doesn’t exist here, so I installed an open wye fitting every few feet in the drain line in the drain-field. I think that the down hill rule will work just fine with this system.
Then I rolled out some weed barrier cloth over the pipes and stones, and the guys back-filled the dirt over the weed cloth.
By the way, do you know the other Rules of Plumbing? Rule Two: Don’t lick your fingers. Rule Three: Payday is Friday. Rule Four: Wear a shirt with long enough tails to tuck well into your pants. This rule is widely ignored by those practicing the trade.
Here are some photos:
That’s all for now. Next: Steel plate column tops.