The mound of dirt in the foreground (hiding the view of the track hoe) was piled up months ago by Brad, saving it so it can later be piled over the top of the drain field. Do you see that tree still standing, seemingly in the middle of the drain field, behind the cab of the track hoe? I asked Brad why it hadn't been cleared out, and he said the rule is that any trees (or stumps) with a trunk diameter greater than 18" must be left in place. Removal of such large trees and their root systems has been deemed dangerous to the operation of the drain field, since the trenches need to be dug/laid in non-disturbed soil.
Here it is a day later; a load of smooth rock has obviously been dumped for use in the trenches:
I was expecting to see pre-perforated PVC pipe, but Brad says it's better to use non-perforated pipe and then drill it on-site every foot or so with a 1/8" hole....that way apparently, the entire system stays fairly "pressurized" and doesn't leak all of the, um, stuff, into the ground in the first few feet of pipe.
Clearly I am NOT an expert on septic systems, but I've been told that our site was approved for a nice, simple system as these things go in today's world. The sewage will flow from the house via gravity into a septic tank (located to the west of the house); from there, a septic pump will push the fluids over\up to the drain field. Pure gravity-fed septic systems (ie, that are gravity-fed all the way out to the drain field) are rarely approved anymore, or so Brad said. A pressure-system (what we will have) is however pretty simple and not too costly to install; if our site had poor soil drainage (this is what soils engineers test for when they do a "perc test"), the septic engineer would have been forced to design a more ornate system, eg a "sand mound" system where they bring in umpteen truckloads of sand to create an artificially well-drained area for the drain field. That would have been much more costly, I'm glad we didn't have to do that.
In this picture, I'm standing in the middle of the drain field looking back toward the house (obv):
See that fern in the left foreground? It's sitting right behind a hole (it's hard to see), which is about 2' in diameter and about 2-3' deep, and is also marked with an orange flag. That hole is a soil drainage test hole - basically our septic engineer (Dean) dug the hole (many, many months ago), filled it with water (not sure how high), then used a stop watch to time how long it took to drain. Again, this is also known as a "perc test" ("perc" is short for "percolate"). There are several such holes in the drain field area, and Brad says he is required to leave them untouched so that the inspector knows for sure that the septic field was actually built in the approved location.
While he had his equipment back on site, we also decided to have Brad clear more space in front of the house (I mentioned this idea in a previous post). This isn't the best picture, but you can get an idea here of how much additional clearing was done (off to the right):
See the new dirt driveway emerging from the trees? We decided to leave a little "island" of trees to the left of that, since the transformer sits next to that location already, and it will also make a nice spot to camoflage the visible dome of the propane tank after it is installed.
The air-conditioning guys are on-site doing their things, and the electrician and plumber are doing final details...progress on the mechanical systems has been great and I'll have another post over the weekend to show details.