Between bad weather, a recent family-wide visit by the “puke fairy” and a bunch of chores I am still trying to battle…
And as we work and toil here at “Corten Central”, I’m going to take another opportunity to reach into the mailbag, and answer a question that I get asked all the time.
Recently, I was asked a question about the “nuts and bolts of the land – part” of an ISBU home building project.
Hey Alex, I understand that your estimates are based solely upon construction costs…But! If I were to ask you “What sort of price range should I expect for a Septic Tank for a family of up to 4 people”, would you be able to give an educated guess?
Reason being, I turned 23 last month and I became debt free. (Editor’s note: So we know that James is a braggart… ;)) I’m essentially able to save 75% of every paycheck by staying with my wonderful family (currently that’s saving a total of $2000 a month) and I want to be able to save up to purchase a section of forested land in order to begin my life in a “Corten Castle” 🙂
From your e-Book, I was able to find the layout that I would love to start off with and continually add more features to it over time. I’m planning on saving up the $28,000 or so for construction costs, and will be skimming over the real estate ads in my area to find out what the costs are going for now.
Love your e-book by the way. Hoping time will pass by faster until your Master How To Book on Shipping Container Homes is released =)
For some reason, people think I’m the guy to consult about poop. I don’t know why? It’s not like… um…er… never mind. Anyway, I get asked this all the time, so rather than bury the answer in a comment, I’m going to dedicate a a big, stinky, um… er… post to it.
Before the shipping containers (ISBUs) arrive for their conversion into your Corten Castle, you’re going to have to create a “home” for them.
This will involve some site preparation, a foundation, a power pole or power system of some type, and then… water and a septic system.
We’ve already talked about how most ISBU homes are built rurally, due to the lack of building codes and allowances for their construction. This means that you can’t just “tie into existing sewer or power grids” in most cases. So, you’re going to need to allow for that in your budget.
Today, we’ll talk about septic systems;
We all know what a septic system is for, so I’ll skip that part, okay? 😉
Wait, never mind. If I skip this part somebody (probably TED, that $&%^#@!!!) is sure to ask;
“But Ronin, how does it work? Hmmmm?”
Okay, Septic 101:
Septic systems are on-site systems designed to safely dispose of biological sanitary waste.
Let’s dispel the myths, first;
The two most common myths on “septic system function” are;
- The septic tank treats the sewage, and
- The soil filters the remaining particles creating pure water underground.
Nope. On both counts.
The septic tank is merely a box that holds sewage. Inside the box, solids settle and fall to the bottom. Anything lighter… like grease and other particles from the sewage float to the top.
The septic tank is just a really disgusting “gravy boat” (I recently read that and it stuck in my head, so I thought I’d share it with you) that meters out “liquid sewage” to the drainfield (leach field) while storing the lions share of the heavy solids and indigestible bits, which will have to be pumped out later.
Just like in your stomach, anaerobic bacteria (water breathing little “bugs”) work to reduce the “strength” of the sewage, but not much in the way of actual “treatment” happens in the septic tank.
The separated liquid containing only water and the dissolved sewage solids (called “effluent”) flows out of the septic tank through a pipe into the leach field. Here it spreads out in a series of trenches.
Now is where the real “biology part” happens. Air breathing, aerobic bacteria lives in the soil (in fact, you’ll find about 30 million organisms – give or take – living in a single teaspoon of soil – Thank you Science Channel). The aerobic bacteria thrive in the area of the trenches and wait patiently for the effluent because it’s their food source. The bacteria consumes all the organic material in the sewage, and according to “Dr. Science…” everything in sewage is organic. Or, at least it’s supposed to be.
See? Organic is GOOD, and GREEN is about to get greener, because all the grass over your leach field will love the “natural” fertilizers that you’re pumping into it’s roots.
Septic systems aren’t really that complicated. It’s essentially a three part system; a big holding tank, a distribution “box” and a series of lines that run out into your yard to form a “leach field”.
Bacteria in the septic tank separates the “gunk” into water, gas, and sludge. Wait, add “scum” to that list, as you’ll see it floating on the top of your tank, if you’re crazy enough to want to go look for it. 😉
Septic tanks are’nt just big empty cavities. They have baffles in them that keep the bad stuff in and let the good stuff out…
Okay, maybe not “good” stuff… just “less bad” stuff… 😉
The baffles will stop scum from getting out and keep the sludge on the bottom of the tank, and out of your lines.
Septic tanks are also vented to allow the gases created by the bacterial action to be “bled off”.
From the septic tank, the “fluids” (the “less bad ” stuff) flows out into a small distribution “box’ where it’s “distributed” to your leach field, thru pipes.
Note that the soil also acts as a filter to catch any small particles of solid matter that end up being carried out of the tank with the fluid.
And that sludge that doesn’t go anywhere? Eventually (in a few years) it’ll need to be removed. Ewww.
All I can say is that this ain’t a DIY job that I want. Call a pumper!
A decent quality septic system should last you about 30 years.
But how BIG a system do I need?
The size of septic tank and the amount of field line your system will require will depend on two factors.
The first of these is called a “percolation test”.
“Perc Tests” are designed to simulate the conditions in a septic system.
Here’s how they work;
You dig a series of holes in your yard about 2 feet deep, measuring 6-12 inches in diameter dug in the area of the proposed septic system. (The depth of the test holes will vary depending on your soil content, but it’s usually not greater than 24 inches.)
Then you fill the holes with water. The idea is to saturate the soil and then after THAT water drains away, you refill the hole to a depth of about 12″ of water.
Now, it’s time for the “test”.
Over the next 30-60 minutes, the rate at which the water drains away is measured. This measurement will provide you with the “minutes per inch” numbers you’ll need to use to design your septic system.
Simply put, if the water in your test hole drops uniformly 1\4 inch every five minutes the rate would be 20 minutes per inch.
Most health codes provides a simple table that determines the size of the system based on the measured perk rate and the number of bedrooms in the home, and you can get this from your local city or county government office.
Suffice to say, the greater the number of bedrooms and the slower the percolation rate, the larger the system required.
While you can do this test yourself, it’s usually preformed by a licensed tester, and by the time they’re done they can usually tell you how big your system will have to be, so that you can “bid it out”.
For more information, you can check here.
In my experience, the average small (ISBU) home will require a 1,000 gallon septic tank and approx. 300′ of field line.
There are many variables here.
The average septic system includes a septic tank made of concrete or plastic/fiberglass that is connected to your home by a 4″ PVC pipe.
That tank is attached to a network called “field lines.” These field lines run out into your yard and their purpose is to distribute the graywater to someplace other than your bathroom floor!
The field lines are constructed of 4″ perforated PVC pipe laid in a bed of gravel. You dig a trench, you line it with gravel. “Geotex” (geotextile material) helps inhibit root and debris obstruction to your field line pipe. You can also use building paper, and some other stuff, in place of the Geotex. You’re just creating a barrier. Cover this all up with soil and plant grass.
Don’t plant trees anywhere near your leach field. If you do, the roots from those trees will seek out that fertilizer enriched graywater, and you’ll end up with a leach field full of busted pipes. Trust me on this.
In some cases, you’re not going to be able to locate your drainage field next to your septic tank. Unfortunately, it’s just the way it works sometimes. When this happens, you’re going to have to pump the waste water from the septic tank into the lines.
This costs more. obviously.
Other factors, such as unusual soil conditions or restricted space, can cause additional modifications to the system which can result in much higher costs.
I can already hear James howling into the wind:
“But Ronin, for cryin’ out loud! ALL I ASKED IS WHAT IT COSTS!” 🙂
Okay, okay… ya whiner… 😉 A basic 1,000 gallon septic system can range from $1,500 to $4,000, depending on where you live and what materials cost.
If you live someplace expensive, or if you have really crappy soil (no pun intended) it can cost more. I just had a family tell me that the best quote they could get in their area was almost $5,000.00, and they were even doing some of the work themselves.
Let me stress that getting multiple bids is important. You’ll often find that “contractor pricing” is all over the map.
And check references!
Want to know more about septic systems?
Image credits: Schematics – http://www.coolray.com, Trench Diagram – Daniel Friedman
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