On 9/12/2015 1:25 PM, Arthur Conan Doyle wrote:
Don Y wrote:

Is it a single unit? Or, three interconnected tanks acting as a 3-chamber
tank? Presumably, the partitions between chambers give the tank extra
load carrying strength (shorter spans between "uprights")? How many folks
in your household to require such a unit? (or, is the size a consequence of
its role as "advanced" treatment?)

It's a single unit with two internal partitions. Sort of like a central ball
with two wings attached.

So, three conjoined spheres? Or, a sphere with a "box" growing out of each
ear?

Three chambers are reqquired to qualify as an advanced
treatment unit. First chamber is called the trash tank. It works like a standard
aerobic septic tank. Second (center) tank has a compressor driven bubbler for
aerobic decomposition.

Thus, you're moving much of the functionality of the field *into* the
tank.

Third tank is a staging tank for the pump that pushes
effluent out to the field through a network of spider pipes. ATUs are required
when there is insufficient top soil to put a standard field in. In our case, we
have about 6" of dirt before hitting fractured limestone.

It would be a similar problem here -- though not with bedrock but, rather,
just the high clay content of our soil. E.g., I can dig a 3 ft deep hole,
fill it with water from a garden hose and come back to find it essentially
unchanged a day later.

[You can rent a shovel attachment for a jack-hammer if you intend to
do any serious "planting", herre]

How far below grade is yours? What type of soil? Aside from grass, does
it support any plantings? Who chose the location? What precautions have
you taken to ensure future home owners are aware of its location and
restrictions on use of that portion of the "yard"? What instructions
did the *installer* leave with you regarding this type of use? (Or,
did he just worry about getting paid?)

The actual tank top is about 6-10 inches under grade, but there are three risers
that are exposed.

So, it's location is fairly obvious to anyone -- even folks who might not
know *what* it is will likely recognize that there is *something* buried
there. In our case, we want to hide the day-to-day existence of the
tank (else we could opt for the easy solution of siting it ABOVE grade).

The builder chose the location, but given that the house is
built on the side of a mountain, there wasn't a huge amount of choice where it
had to go. The hole for the tank had to be jack hammered into stone. Fortunately
it's on the opposide side of the house from the driveway, so no possibility of
driving over it.

If we end up putting a tank in the front yard, it will be located alongside
the driveway -- the intuitive location for "extra vehicles" to park :
Hence the desire to get the tank into the back or side yards where it is
less likely to be "casually" driven over.

[A guest of our neighbor parked her car on the edge of the roadway -- up
beyond the curb line. In doing so, managed to set one wheel on the
cast iron "box" that surrounds the neighbor's below-grade water meter.
Expensive repair. We like to ANTICIPATE such problems before being victimized
by them!]

The county requires a licensed maintenence company inspect it every 6 months.

Ouch! Though it appears you have no other (sewer) alternatives. Do you also
recycle grey water (to keep the load down on the septic system)?

What sorts of problems is the inspection *intended* to catch? And, are
these *real* problems or just "possible" problems?

[E.g., here, our irrigation systems are required to have anti-siphon
mechanisms built in (at least 12" above the highest point) to ensure
an air break if municipal water pressure falls (or, is locally reduced
from pumping at a hydrant, etc.). But, I suspect that isn't a real
problem as many homes do NOT comply with this requirement (and we've
not heard of water supply contamination as a result of drawing
"surface water" back into the system]

That and the operating instructions are included in a house manual we keep when
it comes time to sell.

We would obviously have to let future owners know of its location.
They'd wonder about the extra electrics, plumbing, etc. And, it would
be an *asset* so we'd not want to hide the fact.

OTOH, people forget stuff. Like the folks who dug up the gas main
down the block, the neighbor who managed to cut the CATV feed for
the neighborhood, *me* forgetting where all the low voltage landscape
lighting cables are located, etc.